linux/tools/lguest/lguest.c
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   1/*P:100
   2 * This is the Launcher code, a simple program which lays out the "physical"
   3 * memory for the new Guest by mapping the kernel image and the virtual
   4 * devices, then opens /dev/lguest to tell the kernel about the Guest and
   5 * control it.
   6:*/
   7#define _LARGEFILE64_SOURCE
   8#define _GNU_SOURCE
   9#include <stdio.h>
  10#include <string.h>
  11#include <unistd.h>
  12#include <err.h>
  13#include <stdint.h>
  14#include <stdlib.h>
  15#include <elf.h>
  16#include <sys/mman.h>
  17#include <sys/param.h>
  18#include <sys/types.h>
  19#include <sys/stat.h>
  20#include <sys/wait.h>
  21#include <sys/eventfd.h>
  22#include <fcntl.h>
  23#include <stdbool.h>
  24#include <errno.h>
  25#include <ctype.h>
  26#include <sys/socket.h>
  27#include <sys/ioctl.h>
  28#include <sys/time.h>
  29#include <time.h>
  30#include <netinet/in.h>
  31#include <net/if.h>
  32#include <linux/sockios.h>
  33#include <linux/if_tun.h>
  34#include <sys/uio.h>
  35#include <termios.h>
  36#include <getopt.h>
  37#include <assert.h>
  38#include <sched.h>
  39#include <limits.h>
  40#include <stddef.h>
  41#include <signal.h>
  42#include <pwd.h>
  43#include <grp.h>
  44#include <sys/user.h>
  45#include <linux/pci_regs.h>
  46
  47#ifndef VIRTIO_F_ANY_LAYOUT
  48#define VIRTIO_F_ANY_LAYOUT             27
  49#endif
  50
  51/*L:110
  52 * We can ignore the 43 include files we need for this program, but I do want
  53 * to draw attention to the use of kernel-style types.
  54 *
  55 * As Linus said, "C is a Spartan language, and so should your naming be."  I
  56 * like these abbreviations, so we define them here.  Note that u64 is always
  57 * unsigned long long, which works on all Linux systems: this means that we can
  58 * use %llu in printf for any u64.
  59 */
  60typedef unsigned long long u64;
  61typedef uint32_t u32;
  62typedef uint16_t u16;
  63typedef uint8_t u8;
  64/*:*/
  65
  66#define VIRTIO_CONFIG_NO_LEGACY
  67#define VIRTIO_PCI_NO_LEGACY
  68#define VIRTIO_BLK_NO_LEGACY
  69#define VIRTIO_NET_NO_LEGACY
  70
  71/* Use in-kernel ones, which defines VIRTIO_F_VERSION_1 */
  72#include "../../include/uapi/linux/virtio_config.h"
  73#include "../../include/uapi/linux/virtio_net.h"
  74#include "../../include/uapi/linux/virtio_blk.h"
  75#include "../../include/uapi/linux/virtio_console.h"
  76#include "../../include/uapi/linux/virtio_rng.h"
  77#include <linux/virtio_ring.h>
  78#include "../../include/uapi/linux/virtio_pci.h"
  79#include <asm/bootparam.h>
  80#include "../../include/linux/lguest_launcher.h"
  81
  82#define BRIDGE_PFX "bridge:"
  83#ifndef SIOCBRADDIF
  84#define SIOCBRADDIF     0x89a2          /* add interface to bridge      */
  85#endif
  86/* We can have up to 256 pages for devices. */
  87#define DEVICE_PAGES 256
  88/* This will occupy 3 pages: it must be a power of 2. */
  89#define VIRTQUEUE_NUM 256
  90
  91/*L:120
  92 * verbose is both a global flag and a macro.  The C preprocessor allows
  93 * this, and although I wouldn't recommend it, it works quite nicely here.
  94 */
  95static bool verbose;
  96#define verbose(args...) \
  97        do { if (verbose) printf(args); } while(0)
  98/*:*/
  99
 100/* The pointer to the start of guest memory. */
 101static void *guest_base;
 102/* The maximum guest physical address allowed, and maximum possible. */
 103static unsigned long guest_limit, guest_max, guest_mmio;
 104/* The /dev/lguest file descriptor. */
 105static int lguest_fd;
 106
 107/* a per-cpu variable indicating whose vcpu is currently running */
 108static unsigned int __thread cpu_id;
 109
 110/* 5 bit device number in the PCI_CONFIG_ADDR => 32 only */
 111#define MAX_PCI_DEVICES 32
 112
 113/* This is our list of devices. */
 114struct device_list {
 115        /* Counter to assign interrupt numbers. */
 116        unsigned int next_irq;
 117
 118        /* Counter to print out convenient device numbers. */
 119        unsigned int device_num;
 120
 121        /* PCI devices. */
 122        struct device *pci[MAX_PCI_DEVICES];
 123};
 124
 125/* The list of Guest devices, based on command line arguments. */
 126static struct device_list devices;
 127
 128/*
 129 * Just like struct virtio_pci_cfg_cap in uapi/linux/virtio_pci.h,
 130 * but uses a u32 explicitly for the data.
 131 */
 132struct virtio_pci_cfg_cap_u32 {
 133        struct virtio_pci_cap cap;
 134        u32 pci_cfg_data; /* Data for BAR access. */
 135};
 136
 137struct virtio_pci_mmio {
 138        struct virtio_pci_common_cfg cfg;
 139        u16 notify;
 140        u8 isr;
 141        u8 padding;
 142        /* Device-specific configuration follows this. */
 143};
 144
 145/* This is the layout (little-endian) of the PCI config space. */
 146struct pci_config {
 147        u16 vendor_id, device_id;
 148        u16 command, status;
 149        u8 revid, prog_if, subclass, class;
 150        u8 cacheline_size, lat_timer, header_type, bist;
 151        u32 bar[6];
 152        u32 cardbus_cis_ptr;
 153        u16 subsystem_vendor_id, subsystem_device_id;
 154        u32 expansion_rom_addr;
 155        u8 capabilities, reserved1[3];
 156        u32 reserved2;
 157        u8 irq_line, irq_pin, min_grant, max_latency;
 158
 159        /* Now, this is the linked capability list. */
 160        struct virtio_pci_cap common;
 161        struct virtio_pci_notify_cap notify;
 162        struct virtio_pci_cap isr;
 163        struct virtio_pci_cap device;
 164        struct virtio_pci_cfg_cap_u32 cfg_access;
 165};
 166
 167/* The device structure describes a single device. */
 168struct device {
 169        /* The name of this device, for --verbose. */
 170        const char *name;
 171
 172        /* Any queues attached to this device */
 173        struct virtqueue *vq;
 174
 175        /* Is it operational */
 176        bool running;
 177
 178        /* Has it written FEATURES_OK but not re-checked it? */
 179        bool wrote_features_ok;
 180
 181        /* PCI configuration */
 182        union {
 183                struct pci_config config;
 184                u32 config_words[sizeof(struct pci_config) / sizeof(u32)];
 185        };
 186
 187        /* Features we offer, and those accepted. */
 188        u64 features, features_accepted;
 189
 190        /* Device-specific config hangs off the end of this. */
 191        struct virtio_pci_mmio *mmio;
 192
 193        /* PCI MMIO resources (all in BAR0) */
 194        size_t mmio_size;
 195        u32 mmio_addr;
 196
 197        /* Device-specific data. */
 198        void *priv;
 199};
 200
 201/* The virtqueue structure describes a queue attached to a device. */
 202struct virtqueue {
 203        struct virtqueue *next;
 204
 205        /* Which device owns me. */
 206        struct device *dev;
 207
 208        /* Name for printing errors. */
 209        const char *name;
 210
 211        /* The actual ring of buffers. */
 212        struct vring vring;
 213
 214        /* The information about this virtqueue (we only use queue_size on) */
 215        struct virtio_pci_common_cfg pci_config;
 216
 217        /* Last available index we saw. */
 218        u16 last_avail_idx;
 219
 220        /* How many are used since we sent last irq? */
 221        unsigned int pending_used;
 222
 223        /* Eventfd where Guest notifications arrive. */
 224        int eventfd;
 225
 226        /* Function for the thread which is servicing this virtqueue. */
 227        void (*service)(struct virtqueue *vq);
 228        pid_t thread;
 229};
 230
 231/* Remember the arguments to the program so we can "reboot" */
 232static char **main_args;
 233
 234/* The original tty settings to restore on exit. */
 235static struct termios orig_term;
 236
 237/*
 238 * We have to be careful with barriers: our devices are all run in separate
 239 * threads and so we need to make sure that changes visible to the Guest happen
 240 * in precise order.
 241 */
 242#define wmb() __asm__ __volatile__("" : : : "memory")
 243#define rmb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory")
 244#define mb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory")
 245
 246/* Wrapper for the last available index.  Makes it easier to change. */
 247#define lg_last_avail(vq)       ((vq)->last_avail_idx)
 248
 249/*
 250 * The virtio configuration space is defined to be little-endian.  x86 is
 251 * little-endian too, but it's nice to be explicit so we have these helpers.
 252 */
 253#define cpu_to_le16(v16) (v16)
 254#define cpu_to_le32(v32) (v32)
 255#define cpu_to_le64(v64) (v64)
 256#define le16_to_cpu(v16) (v16)
 257#define le32_to_cpu(v32) (v32)
 258#define le64_to_cpu(v64) (v64)
 259
 260/*
 261 * A real device would ignore weird/non-compliant driver behaviour.  We
 262 * stop and flag it, to help debugging Linux problems.
 263 */
 264#define bad_driver(d, fmt, ...) \
 265        errx(1, "%s: bad driver: " fmt, (d)->name, ## __VA_ARGS__)
 266#define bad_driver_vq(vq, fmt, ...)                            \
 267        errx(1, "%s vq %s: bad driver: " fmt, (vq)->dev->name, \
 268             vq->name, ## __VA_ARGS__)
 269
 270/* Is this iovec empty? */
 271static bool iov_empty(const struct iovec iov[], unsigned int num_iov)
 272{
 273        unsigned int i;
 274
 275        for (i = 0; i < num_iov; i++)
 276                if (iov[i].iov_len)
 277                        return false;
 278        return true;
 279}
 280
 281/* Take len bytes from the front of this iovec. */
 282static void iov_consume(struct device *d,
 283                        struct iovec iov[], unsigned num_iov,
 284                        void *dest, unsigned len)
 285{
 286        unsigned int i;
 287
 288        for (i = 0; i < num_iov; i++) {
 289                unsigned int used;
 290
 291                used = iov[i].iov_len < len ? iov[i].iov_len : len;
 292                if (dest) {
 293                        memcpy(dest, iov[i].iov_base, used);
 294                        dest += used;
 295                }
 296                iov[i].iov_base += used;
 297                iov[i].iov_len -= used;
 298                len -= used;
 299        }
 300        if (len != 0)
 301                bad_driver(d, "iovec too short!");
 302}
 303
 304/*L:100
 305 * The Launcher code itself takes us out into userspace, that scary place where
 306 * pointers run wild and free!  Unfortunately, like most userspace programs,
 307 * it's quite boring (which is why everyone likes to hack on the kernel!).
 308 * Perhaps if you make up an Lguest Drinking Game at this point, it will get
 309 * you through this section.  Or, maybe not.
 310 *
 311 * The Launcher sets up a big chunk of memory to be the Guest's "physical"
 312 * memory and stores it in "guest_base".  In other words, Guest physical ==
 313 * Launcher virtual with an offset.
 314 *
 315 * This can be tough to get your head around, but usually it just means that we
 316 * use these trivial conversion functions when the Guest gives us its
 317 * "physical" addresses:
 318 */
 319static void *from_guest_phys(unsigned long addr)
 320{
 321        return guest_base + addr;
 322}
 323
 324static unsigned long to_guest_phys(const void *addr)
 325{
 326        return (addr - guest_base);
 327}
 328
 329/*L:130
 330 * Loading the Kernel.
 331 *
 332 * We start with couple of simple helper routines.  open_or_die() avoids
 333 * error-checking code cluttering the callers:
 334 */
 335static int open_or_die(const char *name, int flags)
 336{
 337        int fd = open(name, flags);
 338        if (fd < 0)
 339                err(1, "Failed to open %s", name);
 340        return fd;
 341}
 342
 343/* map_zeroed_pages() takes a number of pages. */
 344static void *map_zeroed_pages(unsigned int num)
 345{
 346        int fd = open_or_die("/dev/zero", O_RDONLY);
 347        void *addr;
 348
 349        /*
 350         * We use a private mapping (ie. if we write to the page, it will be
 351         * copied). We allocate an extra two pages PROT_NONE to act as guard
 352         * pages against read/write attempts that exceed allocated space.
 353         */
 354        addr = mmap(NULL, getpagesize() * (num+2),
 355                    PROT_NONE, MAP_PRIVATE, fd, 0);
 356
 357        if (addr == MAP_FAILED)
 358                err(1, "Mmapping %u pages of /dev/zero", num);
 359
 360        if (mprotect(addr + getpagesize(), getpagesize() * num,
 361                     PROT_READ|PROT_WRITE) == -1)
 362                err(1, "mprotect rw %u pages failed", num);
 363
 364        /*
 365         * One neat mmap feature is that you can close the fd, and it
 366         * stays mapped.
 367         */
 368        close(fd);
 369
 370        /* Return address after PROT_NONE page */
 371        return addr + getpagesize();
 372}
 373
 374/* Get some bytes which won't be mapped into the guest. */
 375static unsigned long get_mmio_region(size_t size)
 376{
 377        unsigned long addr = guest_mmio;
 378        size_t i;
 379
 380        if (!size)
 381                return addr;
 382
 383        /* Size has to be a power of 2 (and multiple of 16) */
 384        for (i = 1; i < size; i <<= 1);
 385
 386        guest_mmio += i;
 387
 388        return addr;
 389}
 390
 391/*
 392 * This routine is used to load the kernel or initrd.  It tries mmap, but if
 393 * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries),
 394 * it falls back to reading the memory in.
 395 */
 396static void map_at(int fd, void *addr, unsigned long offset, unsigned long len)
 397{
 398        ssize_t r;
 399
 400        /*
 401         * We map writable even though for some segments are marked read-only.
 402         * The kernel really wants to be writable: it patches its own
 403         * instructions.
 404         *
 405         * MAP_PRIVATE means that the page won't be copied until a write is
 406         * done to it.  This allows us to share untouched memory between
 407         * Guests.
 408         */
 409        if (mmap(addr, len, PROT_READ|PROT_WRITE,
 410                 MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED)
 411                return;
 412
 413        /* pread does a seek and a read in one shot: saves a few lines. */
 414        r = pread(fd, addr, len, offset);
 415        if (r != len)
 416                err(1, "Reading offset %lu len %lu gave %zi", offset, len, r);
 417}
 418
 419/*
 420 * This routine takes an open vmlinux image, which is in ELF, and maps it into
 421 * the Guest memory.  ELF = Embedded Linking Format, which is the format used
 422 * by all modern binaries on Linux including the kernel.
 423 *
 424 * The ELF headers give *two* addresses: a physical address, and a virtual
 425 * address.  We use the physical address; the Guest will map itself to the
 426 * virtual address.
 427 *
 428 * We return the starting address.
 429 */
 430static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr)
 431{
 432        Elf32_Phdr phdr[ehdr->e_phnum];
 433        unsigned int i;
 434
 435        /*
 436         * Sanity checks on the main ELF header: an x86 executable with a
 437         * reasonable number of correctly-sized program headers.
 438         */
 439        if (ehdr->e_type != ET_EXEC
 440            || ehdr->e_machine != EM_386
 441            || ehdr->e_phentsize != sizeof(Elf32_Phdr)
 442            || ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr))
 443                errx(1, "Malformed elf header");
 444
 445        /*
 446         * An ELF executable contains an ELF header and a number of "program"
 447         * headers which indicate which parts ("segments") of the program to
 448         * load where.
 449         */
 450
 451        /* We read in all the program headers at once: */
 452        if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0)
 453                err(1, "Seeking to program headers");
 454        if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr))
 455                err(1, "Reading program headers");
 456
 457        /*
 458         * Try all the headers: there are usually only three.  A read-only one,
 459         * a read-write one, and a "note" section which we don't load.
 460         */
 461        for (i = 0; i < ehdr->e_phnum; i++) {
 462                /* If this isn't a loadable segment, we ignore it */
 463                if (phdr[i].p_type != PT_LOAD)
 464                        continue;
 465
 466                verbose("Section %i: size %i addr %p\n",
 467                        i, phdr[i].p_memsz, (void *)phdr[i].p_paddr);
 468
 469                /* We map this section of the file at its physical address. */
 470                map_at(elf_fd, from_guest_phys(phdr[i].p_paddr),
 471                       phdr[i].p_offset, phdr[i].p_filesz);
 472        }
 473
 474        /* The entry point is given in the ELF header. */
 475        return ehdr->e_entry;
 476}
 477
 478/*L:150
 479 * A bzImage, unlike an ELF file, is not meant to be loaded.  You're supposed
 480 * to jump into it and it will unpack itself.  We used to have to perform some
 481 * hairy magic because the unpacking code scared me.
 482 *
 483 * Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote
 484 * a small patch to jump over the tricky bits in the Guest, so now we just read
 485 * the funky header so we know where in the file to load, and away we go!
 486 */
 487static unsigned long load_bzimage(int fd)
 488{
 489        struct boot_params boot;
 490        int r;
 491        /* Modern bzImages get loaded at 1M. */
 492        void *p = from_guest_phys(0x100000);
 493
 494        /*
 495         * Go back to the start of the file and read the header.  It should be
 496         * a Linux boot header (see Documentation/x86/boot.txt)
 497         */
 498        lseek(fd, 0, SEEK_SET);
 499        read(fd, &boot, sizeof(boot));
 500
 501        /* Inside the setup_hdr, we expect the magic "HdrS" */
 502        if (memcmp(&boot.hdr.header, "HdrS", 4) != 0)
 503                errx(1, "This doesn't look like a bzImage to me");
 504
 505        /* Skip over the extra sectors of the header. */
 506        lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET);
 507
 508        /* Now read everything into memory. in nice big chunks. */
 509        while ((r = read(fd, p, 65536)) > 0)
 510                p += r;
 511
 512        /* Finally, code32_start tells us where to enter the kernel. */
 513        return boot.hdr.code32_start;
 514}
 515
 516/*L:140
 517 * Loading the kernel is easy when it's a "vmlinux", but most kernels
 518 * come wrapped up in the self-decompressing "bzImage" format.  With a little
 519 * work, we can load those, too.
 520 */
 521static unsigned long load_kernel(int fd)
 522{
 523        Elf32_Ehdr hdr;
 524
 525        /* Read in the first few bytes. */
 526        if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 527                err(1, "Reading kernel");
 528
 529        /* If it's an ELF file, it starts with "\177ELF" */
 530        if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0)
 531                return map_elf(fd, &hdr);
 532
 533        /* Otherwise we assume it's a bzImage, and try to load it. */
 534        return load_bzimage(fd);
 535}
 536
 537/*
 538 * This is a trivial little helper to align pages.  Andi Kleen hated it because
 539 * it calls getpagesize() twice: "it's dumb code."
 540 *
 541 * Kernel guys get really het up about optimization, even when it's not
 542 * necessary.  I leave this code as a reaction against that.
 543 */
 544static inline unsigned long page_align(unsigned long addr)
 545{
 546        /* Add upwards and truncate downwards. */
 547        return ((addr + getpagesize()-1) & ~(getpagesize()-1));
 548}
 549
 550/*L:180
 551 * An "initial ram disk" is a disk image loaded into memory along with the
 552 * kernel which the kernel can use to boot from without needing any drivers.
 553 * Most distributions now use this as standard: the initrd contains the code to
 554 * load the appropriate driver modules for the current machine.
 555 *
 556 * Importantly, James Morris works for RedHat, and Fedora uses initrds for its
 557 * kernels.  He sent me this (and tells me when I break it).
 558 */
 559static unsigned long load_initrd(const char *name, unsigned long mem)
 560{
 561        int ifd;
 562        struct stat st;
 563        unsigned long len;
 564
 565        ifd = open_or_die(name, O_RDONLY);
 566        /* fstat() is needed to get the file size. */
 567        if (fstat(ifd, &st) < 0)
 568                err(1, "fstat() on initrd '%s'", name);
 569
 570        /*
 571         * We map the initrd at the top of memory, but mmap wants it to be
 572         * page-aligned, so we round the size up for that.
 573         */
 574        len = page_align(st.st_size);
 575        map_at(ifd, from_guest_phys(mem - len), 0, st.st_size);
 576        /*
 577         * Once a file is mapped, you can close the file descriptor.  It's a
 578         * little odd, but quite useful.
 579         */
 580        close(ifd);
 581        verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len);
 582
 583        /* We return the initrd size. */
 584        return len;
 585}
 586/*:*/
 587
 588/*
 589 * Simple routine to roll all the commandline arguments together with spaces
 590 * between them.
 591 */
 592static void concat(char *dst, char *args[])
 593{
 594        unsigned int i, len = 0;
 595
 596        for (i = 0; args[i]; i++) {
 597                if (i) {
 598                        strcat(dst+len, " ");
 599                        len++;
 600                }
 601                strcpy(dst+len, args[i]);
 602                len += strlen(args[i]);
 603        }
 604        /* In case it's empty. */
 605        dst[len] = '\0';
 606}
 607
 608/*L:185
 609 * This is where we actually tell the kernel to initialize the Guest.  We
 610 * saw the arguments it expects when we looked at initialize() in lguest_user.c:
 611 * the base of Guest "physical" memory, the top physical page to allow and the
 612 * entry point for the Guest.
 613 */
 614static void tell_kernel(unsigned long start)
 615{
 616        unsigned long args[] = { LHREQ_INITIALIZE,
 617                                 (unsigned long)guest_base,
 618                                 guest_limit / getpagesize(), start,
 619                                 (guest_mmio+getpagesize()-1) / getpagesize() };
 620        verbose("Guest: %p - %p (%#lx, MMIO %#lx)\n",
 621                guest_base, guest_base + guest_limit,
 622                guest_limit, guest_mmio);
 623        lguest_fd = open_or_die("/dev/lguest", O_RDWR);
 624        if (write(lguest_fd, args, sizeof(args)) < 0)
 625                err(1, "Writing to /dev/lguest");
 626}
 627/*:*/
 628
 629/*L:200
 630 * Device Handling.
 631 *
 632 * When the Guest gives us a buffer, it sends an array of addresses and sizes.
 633 * We need to make sure it's not trying to reach into the Launcher itself, so
 634 * we have a convenient routine which checks it and exits with an error message
 635 * if something funny is going on:
 636 */
 637static void *_check_pointer(struct device *d,
 638                            unsigned long addr, unsigned int size,
 639                            unsigned int line)
 640{
 641        /*
 642         * Check if the requested address and size exceeds the allocated memory,
 643         * or addr + size wraps around.
 644         */
 645        if ((addr + size) > guest_limit || (addr + size) < addr)
 646                bad_driver(d, "%s:%i: Invalid address %#lx",
 647                           __FILE__, line, addr);
 648        /*
 649         * We return a pointer for the caller's convenience, now we know it's
 650         * safe to use.
 651         */
 652        return from_guest_phys(addr);
 653}
 654/* A macro which transparently hands the line number to the real function. */
 655#define check_pointer(d,addr,size) _check_pointer(d, addr, size, __LINE__)
 656
 657/*
 658 * Each buffer in the virtqueues is actually a chain of descriptors.  This
 659 * function returns the next descriptor in the chain, or vq->vring.num if we're
 660 * at the end.
 661 */
 662static unsigned next_desc(struct device *d, struct vring_desc *desc,
 663                          unsigned int i, unsigned int max)
 664{
 665        unsigned int next;
 666
 667        /* If this descriptor says it doesn't chain, we're done. */
 668        if (!(desc[i].flags & VRING_DESC_F_NEXT))
 669                return max;
 670
 671        /* Check they're not leading us off end of descriptors. */
 672        next = desc[i].next;
 673        /* Make sure compiler knows to grab that: we don't want it changing! */
 674        wmb();
 675
 676        if (next >= max)
 677                bad_driver(d, "Desc next is %u", next);
 678
 679        return next;
 680}
 681
 682/*
 683 * This actually sends the interrupt for this virtqueue, if we've used a
 684 * buffer.
 685 */
 686static void trigger_irq(struct virtqueue *vq)
 687{
 688        unsigned long buf[] = { LHREQ_IRQ, vq->dev->config.irq_line };
 689
 690        /* Don't inform them if nothing used. */
 691        if (!vq->pending_used)
 692                return;
 693        vq->pending_used = 0;
 694
 695        /*
 696         * 2.4.7.1:
 697         *
 698         *  If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
 699         *    The driver MUST set flags to 0 or 1. 
 700         */
 701        if (vq->vring.avail->flags > 1)
 702                bad_driver_vq(vq, "avail->flags = %u\n", vq->vring.avail->flags);
 703
 704        /*
 705         * 2.4.7.2:
 706         *
 707         *  If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
 708         *
 709         *     - The device MUST ignore the used_event value.
 710         *     - After the device writes a descriptor index into the used ring:
 711         *         - If flags is 1, the device SHOULD NOT send an interrupt.
 712         *         - If flags is 0, the device MUST send an interrupt.
 713         */
 714        if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) {
 715                return;
 716        }
 717
 718        /*
 719         * 4.1.4.5.1:
 720         *
 721         *  If MSI-X capability is disabled, the device MUST set the Queue
 722         *  Interrupt bit in ISR status before sending a virtqueue notification
 723         *  to the driver.
 724         */
 725        vq->dev->mmio->isr = 0x1;
 726
 727        /* Send the Guest an interrupt tell them we used something up. */
 728        if (write(lguest_fd, buf, sizeof(buf)) != 0)
 729                err(1, "Triggering irq %i", vq->dev->config.irq_line);
 730}
 731
 732/*
 733 * This looks in the virtqueue for the first available buffer, and converts
 734 * it to an iovec for convenient access.  Since descriptors consist of some
 735 * number of output then some number of input descriptors, it's actually two
 736 * iovecs, but we pack them into one and note how many of each there were.
 737 *
 738 * This function waits if necessary, and returns the descriptor number found.
 739 */
 740static unsigned wait_for_vq_desc(struct virtqueue *vq,
 741                                 struct iovec iov[],
 742                                 unsigned int *out_num, unsigned int *in_num)
 743{
 744        unsigned int i, head, max;
 745        struct vring_desc *desc;
 746        u16 last_avail = lg_last_avail(vq);
 747
 748        /*
 749         * 2.4.7.1:
 750         *
 751         *   The driver MUST handle spurious interrupts from the device.
 752         *
 753         * That's why this is a while loop.
 754         */
 755
 756        /* There's nothing available? */
 757        while (last_avail == vq->vring.avail->idx) {
 758                u64 event;
 759
 760                /*
 761                 * Since we're about to sleep, now is a good time to tell the
 762                 * Guest about what we've used up to now.
 763                 */
 764                trigger_irq(vq);
 765
 766                /* OK, now we need to know about added descriptors. */
 767                vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
 768
 769                /*
 770                 * They could have slipped one in as we were doing that: make
 771                 * sure it's written, then check again.
 772                 */
 773                mb();
 774                if (last_avail != vq->vring.avail->idx) {
 775                        vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
 776                        break;
 777                }
 778
 779                /* Nothing new?  Wait for eventfd to tell us they refilled. */
 780                if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event))
 781                        errx(1, "Event read failed?");
 782
 783                /* We don't need to be notified again. */
 784                vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
 785        }
 786
 787        /* Check it isn't doing very strange things with descriptor numbers. */
 788        if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num)
 789                bad_driver_vq(vq, "Guest moved used index from %u to %u",
 790                              last_avail, vq->vring.avail->idx);
 791
 792        /* 
 793         * Make sure we read the descriptor number *after* we read the ring
 794         * update; don't let the cpu or compiler change the order.
 795         */
 796        rmb();
 797
 798        /*
 799         * Grab the next descriptor number they're advertising, and increment
 800         * the index we've seen.
 801         */
 802        head = vq->vring.avail->ring[last_avail % vq->vring.num];
 803        lg_last_avail(vq)++;
 804
 805        /* If their number is silly, that's a fatal mistake. */
 806        if (head >= vq->vring.num)
 807                bad_driver_vq(vq, "Guest says index %u is available", head);
 808
 809        /* When we start there are none of either input nor output. */
 810        *out_num = *in_num = 0;
 811
 812        max = vq->vring.num;
 813        desc = vq->vring.desc;
 814        i = head;
 815
 816        /*
 817         * We have to read the descriptor after we read the descriptor number,
 818         * but there's a data dependency there so the CPU shouldn't reorder
 819         * that: no rmb() required.
 820         */
 821
 822        do {
 823                /*
 824                 * If this is an indirect entry, then this buffer contains a
 825                 * descriptor table which we handle as if it's any normal
 826                 * descriptor chain.
 827                 */
 828                if (desc[i].flags & VRING_DESC_F_INDIRECT) {
 829                        /* 2.4.5.3.1:
 830                         *
 831                         *  The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT
 832                         *  flag unless the VIRTIO_F_INDIRECT_DESC feature was
 833                         *  negotiated.
 834                         */
 835                        if (!(vq->dev->features_accepted &
 836                              (1<<VIRTIO_RING_F_INDIRECT_DESC)))
 837                                bad_driver_vq(vq, "vq indirect not negotiated");
 838
 839                        /*
 840                         * 2.4.5.3.1:
 841                         *
 842                         *   The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT
 843                         *   flag within an indirect descriptor (ie. only one
 844                         *   table per descriptor).
 845                         */
 846                        if (desc != vq->vring.desc)
 847                                bad_driver_vq(vq, "Indirect within indirect");
 848
 849                        /*
 850                         * Proposed update VIRTIO-134 spells this out:
 851                         *
 852                         *   A driver MUST NOT set both VIRTQ_DESC_F_INDIRECT
 853                         *   and VIRTQ_DESC_F_NEXT in flags.
 854                         */
 855                        if (desc[i].flags & VRING_DESC_F_NEXT)
 856                                bad_driver_vq(vq, "indirect and next together");
 857
 858                        if (desc[i].len % sizeof(struct vring_desc))
 859                                bad_driver_vq(vq,
 860                                              "Invalid size for indirect table");
 861                        /*
 862                         * 2.4.5.3.2:
 863                         *
 864                         *  The device MUST ignore the write-only flag
 865                         *  (flags&VIRTQ_DESC_F_WRITE) in the descriptor that
 866                         *  refers to an indirect table.
 867                         *
 868                         * We ignore it here: :)
 869                         */
 870
 871                        max = desc[i].len / sizeof(struct vring_desc);
 872                        desc = check_pointer(vq->dev, desc[i].addr, desc[i].len);
 873                        i = 0;
 874
 875                        /* 2.4.5.3.1:
 876                         *
 877                         *  A driver MUST NOT create a descriptor chain longer
 878                         *  than the Queue Size of the device.
 879                         */
 880                        if (max > vq->pci_config.queue_size)
 881                                bad_driver_vq(vq,
 882                                              "indirect has too many entries");
 883                }
 884
 885                /* Grab the first descriptor, and check it's OK. */
 886                iov[*out_num + *in_num].iov_len = desc[i].len;
 887                iov[*out_num + *in_num].iov_base
 888                        = check_pointer(vq->dev, desc[i].addr, desc[i].len);
 889                /* If this is an input descriptor, increment that count. */
 890                if (desc[i].flags & VRING_DESC_F_WRITE)
 891                        (*in_num)++;
 892                else {
 893                        /*
 894                         * If it's an output descriptor, they're all supposed
 895                         * to come before any input descriptors.
 896                         */
 897                        if (*in_num)
 898                                bad_driver_vq(vq,
 899                                              "Descriptor has out after in");
 900                        (*out_num)++;
 901                }
 902
 903                /* If we've got too many, that implies a descriptor loop. */
 904                if (*out_num + *in_num > max)
 905                        bad_driver_vq(vq, "Looped descriptor");
 906        } while ((i = next_desc(vq->dev, desc, i, max)) != max);
 907
 908        return head;
 909}
 910
 911/*
 912 * After we've used one of their buffers, we tell the Guest about it.  Sometime
 913 * later we'll want to send them an interrupt using trigger_irq(); note that
 914 * wait_for_vq_desc() does that for us if it has to wait.
 915 */
 916static void add_used(struct virtqueue *vq, unsigned int head, int len)
 917{
 918        struct vring_used_elem *used;
 919
 920        /*
 921         * The virtqueue contains a ring of used buffers.  Get a pointer to the
 922         * next entry in that used ring.
 923         */
 924        used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num];
 925        used->id = head;
 926        used->len = len;
 927        /* Make sure buffer is written before we update index. */
 928        wmb();
 929        vq->vring.used->idx++;
 930        vq->pending_used++;
 931}
 932
 933/* And here's the combo meal deal.  Supersize me! */
 934static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len)
 935{
 936        add_used(vq, head, len);
 937        trigger_irq(vq);
 938}
 939
 940/*
 941 * The Console
 942 *
 943 * We associate some data with the console for our exit hack.
 944 */
 945struct console_abort {
 946        /* How many times have they hit ^C? */
 947        int count;
 948        /* When did they start? */
 949        struct timeval start;
 950};
 951
 952/* This is the routine which handles console input (ie. stdin). */
 953static void console_input(struct virtqueue *vq)
 954{
 955        int len;
 956        unsigned int head, in_num, out_num;
 957        struct console_abort *abort = vq->dev->priv;
 958        struct iovec iov[vq->vring.num];
 959
 960        /* Make sure there's a descriptor available. */
 961        head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
 962        if (out_num)
 963                bad_driver_vq(vq, "Output buffers in console in queue?");
 964
 965        /* Read into it.  This is where we usually wait. */
 966        len = readv(STDIN_FILENO, iov, in_num);
 967        if (len <= 0) {
 968                /* Ran out of input? */
 969                warnx("Failed to get console input, ignoring console.");
 970                /*
 971                 * For simplicity, dying threads kill the whole Launcher.  So
 972                 * just nap here.
 973                 */
 974                for (;;)
 975                        pause();
 976        }
 977
 978        /* Tell the Guest we used a buffer. */
 979        add_used_and_trigger(vq, head, len);
 980
 981        /*
 982         * Three ^C within one second?  Exit.
 983         *
 984         * This is such a hack, but works surprisingly well.  Each ^C has to
 985         * be in a buffer by itself, so they can't be too fast.  But we check
 986         * that we get three within about a second, so they can't be too
 987         * slow.
 988         */
 989        if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) {
 990                abort->count = 0;
 991                return;
 992        }
 993
 994        abort->count++;
 995        if (abort->count == 1)
 996                gettimeofday(&abort->start, NULL);
 997        else if (abort->count == 3) {
 998                struct timeval now;
 999                gettimeofday(&now, NULL);
1000                /* Kill all Launcher processes with SIGINT, like normal ^C */
1001                if (now.tv_sec <= abort->start.tv_sec+1)
1002                        kill(0, SIGINT);
1003                abort->count = 0;
1004        }
1005}
1006
1007/* This is the routine which handles console output (ie. stdout). */
1008static void console_output(struct virtqueue *vq)
1009{
1010        unsigned int head, out, in;
1011        struct iovec iov[vq->vring.num];
1012
1013        /* We usually wait in here, for the Guest to give us something. */
1014        head = wait_for_vq_desc(vq, iov, &out, &in);
1015        if (in)
1016                bad_driver_vq(vq, "Input buffers in console output queue?");
1017
1018        /* writev can return a partial write, so we loop here. */
1019        while (!iov_empty(iov, out)) {
1020                int len = writev(STDOUT_FILENO, iov, out);
1021                if (len <= 0) {
1022                        warn("Write to stdout gave %i (%d)", len, errno);
1023                        break;
1024                }
1025                iov_consume(vq->dev, iov, out, NULL, len);
1026        }
1027
1028        /*
1029         * We're finished with that buffer: if we're going to sleep,
1030         * wait_for_vq_desc() will prod the Guest with an interrupt.
1031         */
1032        add_used(vq, head, 0);
1033}
1034
1035/*
1036 * The Network
1037 *
1038 * Handling output for network is also simple: we get all the output buffers
1039 * and write them to /dev/net/tun.
1040 */
1041struct net_info {
1042        int tunfd;
1043};
1044
1045static void net_output(struct virtqueue *vq)
1046{
1047        struct net_info *net_info = vq->dev->priv;
1048        unsigned int head, out, in;
1049        struct iovec iov[vq->vring.num];
1050
1051        /* We usually wait in here for the Guest to give us a packet. */
1052        head = wait_for_vq_desc(vq, iov, &out, &in);
1053        if (in)
1054                bad_driver_vq(vq, "Input buffers in net output queue?");
1055        /*
1056         * Send the whole thing through to /dev/net/tun.  It expects the exact
1057         * same format: what a coincidence!
1058         */
1059        if (writev(net_info->tunfd, iov, out) < 0)
1060                warnx("Write to tun failed (%d)?", errno);
1061
1062        /*
1063         * Done with that one; wait_for_vq_desc() will send the interrupt if
1064         * all packets are processed.
1065         */
1066        add_used(vq, head, 0);
1067}
1068
1069/*
1070 * Handling network input is a bit trickier, because I've tried to optimize it.
1071 *
1072 * First we have a helper routine which tells is if from this file descriptor
1073 * (ie. the /dev/net/tun device) will block:
1074 */
1075static bool will_block(int fd)
1076{
1077        fd_set fdset;
1078        struct timeval zero = { 0, 0 };
1079        FD_ZERO(&fdset);
1080        FD_SET(fd, &fdset);
1081        return select(fd+1, &fdset, NULL, NULL, &zero) != 1;
1082}
1083
1084/*
1085 * This handles packets coming in from the tun device to our Guest.  Like all
1086 * service routines, it gets called again as soon as it returns, so you don't
1087 * see a while(1) loop here.
1088 */
1089static void net_input(struct virtqueue *vq)
1090{
1091        int len;
1092        unsigned int head, out, in;
1093        struct iovec iov[vq->vring.num];
1094        struct net_info *net_info = vq->dev->priv;
1095
1096        /*
1097         * Get a descriptor to write an incoming packet into.  This will also
1098         * send an interrupt if they're out of descriptors.
1099         */
1100        head = wait_for_vq_desc(vq, iov, &out, &in);
1101        if (out)
1102                bad_driver_vq(vq, "Output buffers in net input queue?");
1103
1104        /*
1105         * If it looks like we'll block reading from the tun device, send them
1106         * an interrupt.
1107         */
1108        if (vq->pending_used && will_block(net_info->tunfd))
1109                trigger_irq(vq);
1110
1111        /*
1112         * Read in the packet.  This is where we normally wait (when there's no
1113         * incoming network traffic).
1114         */
1115        len = readv(net_info->tunfd, iov, in);
1116        if (len <= 0)
1117                warn("Failed to read from tun (%d).", errno);
1118
1119        /*
1120         * Mark that packet buffer as used, but don't interrupt here.  We want
1121         * to wait until we've done as much work as we can.
1122         */
1123        add_used(vq, head, len);
1124}
1125/*:*/
1126
1127/* This is the helper to create threads: run the service routine in a loop. */
1128static int do_thread(void *_vq)
1129{
1130        struct virtqueue *vq = _vq;
1131
1132        for (;;)
1133                vq->service(vq);
1134        return 0;
1135}
1136
1137/*
1138 * When a child dies, we kill our entire process group with SIGTERM.  This
1139 * also has the side effect that the shell restores the console for us!
1140 */
1141static void kill_launcher(int signal)
1142{
1143        kill(0, SIGTERM);
1144}
1145
1146static void reset_vq_pci_config(struct virtqueue *vq)
1147{
1148        vq->pci_config.queue_size = VIRTQUEUE_NUM;
1149        vq->pci_config.queue_enable = 0;
1150}
1151
1152static void reset_device(struct device *dev)
1153{
1154        struct virtqueue *vq;
1155
1156        verbose("Resetting device %s\n", dev->name);
1157
1158        /* Clear any features they've acked. */
1159        dev->features_accepted = 0;
1160
1161        /* We're going to be explicitly killing threads, so ignore them. */
1162        signal(SIGCHLD, SIG_IGN);
1163
1164        /*
1165         * 4.1.4.3.1:
1166         *
1167         *   The device MUST present a 0 in queue_enable on reset. 
1168         *
1169         * This means we set it here, and reset the saved ones in every vq.
1170         */
1171        dev->mmio->cfg.queue_enable = 0;
1172
1173        /* Get rid of the virtqueue threads */
1174        for (vq = dev->vq; vq; vq = vq->next) {
1175                vq->last_avail_idx = 0;
1176                reset_vq_pci_config(vq);
1177                if (vq->thread != (pid_t)-1) {
1178                        kill(vq->thread, SIGTERM);
1179                        waitpid(vq->thread, NULL, 0);
1180                        vq->thread = (pid_t)-1;
1181                }
1182        }
1183        dev->running = false;
1184        dev->wrote_features_ok = false;
1185
1186        /* Now we care if threads die. */
1187        signal(SIGCHLD, (void *)kill_launcher);
1188}
1189
1190static void cleanup_devices(void)
1191{
1192        unsigned int i;
1193
1194        for (i = 1; i < MAX_PCI_DEVICES; i++) {
1195                struct device *d = devices.pci[i];
1196                if (!d)
1197                        continue;
1198                reset_device(d);
1199        }
1200
1201        /* If we saved off the original terminal settings, restore them now. */
1202        if (orig_term.c_lflag & (ISIG|ICANON|ECHO))
1203                tcsetattr(STDIN_FILENO, TCSANOW, &orig_term);
1204}
1205
1206/*L:217
1207 * We do PCI.  This is mainly done to let us test the kernel virtio PCI
1208 * code.
1209 */
1210
1211/* Linux expects a PCI host bridge: ours is a dummy, and first on the bus. */
1212static struct device pci_host_bridge;
1213
1214static void init_pci_host_bridge(void)
1215{
1216        pci_host_bridge.name = "PCI Host Bridge";
1217        pci_host_bridge.config.class = 0x06; /* bridge */
1218        pci_host_bridge.config.subclass = 0; /* host bridge */
1219        devices.pci[0] = &pci_host_bridge;
1220}
1221
1222/* The IO ports used to read the PCI config space. */
1223#define PCI_CONFIG_ADDR 0xCF8
1224#define PCI_CONFIG_DATA 0xCFC
1225
1226/*
1227 * Not really portable, but does help readability: this is what the Guest
1228 * writes to the PCI_CONFIG_ADDR IO port.
1229 */
1230union pci_config_addr {
1231        struct {
1232                unsigned mbz: 2;
1233                unsigned offset: 6;
1234                unsigned funcnum: 3;
1235                unsigned devnum: 5;
1236                unsigned busnum: 8;
1237                unsigned reserved: 7;
1238                unsigned enabled : 1;
1239        } bits;
1240        u32 val;
1241};
1242
1243/*
1244 * We cache what they wrote to the address port, so we know what they're
1245 * talking about when they access the data port.
1246 */
1247static union pci_config_addr pci_config_addr;
1248
1249static struct device *find_pci_device(unsigned int index)
1250{
1251        return devices.pci[index];
1252}
1253
1254/* PCI can do 1, 2 and 4 byte reads; we handle that here. */
1255static void ioread(u16 off, u32 v, u32 mask, u32 *val)
1256{
1257        assert(off < 4);
1258        assert(mask == 0xFF || mask == 0xFFFF || mask == 0xFFFFFFFF);
1259        *val = (v >> (off * 8)) & mask;
1260}
1261
1262/* PCI can do 1, 2 and 4 byte writes; we handle that here. */
1263static void iowrite(u16 off, u32 v, u32 mask, u32 *dst)
1264{
1265        assert(off < 4);
1266        assert(mask == 0xFF || mask == 0xFFFF || mask == 0xFFFFFFFF);
1267        *dst &= ~(mask << (off * 8));
1268        *dst |= (v & mask) << (off * 8);
1269}
1270
1271/*
1272 * Where PCI_CONFIG_DATA accesses depends on the previous write to
1273 * PCI_CONFIG_ADDR.
1274 */
1275static struct device *dev_and_reg(u32 *reg)
1276{
1277        if (!pci_config_addr.bits.enabled)
1278                return NULL;
1279
1280        if (pci_config_addr.bits.funcnum != 0)
1281                return NULL;
1282
1283        if (pci_config_addr.bits.busnum != 0)
1284                return NULL;
1285
1286        if (pci_config_addr.bits.offset * 4 >= sizeof(struct pci_config))
1287                return NULL;
1288
1289        *reg = pci_config_addr.bits.offset;
1290        return find_pci_device(pci_config_addr.bits.devnum);
1291}
1292
1293/*
1294 * We can get invalid combinations of values while they're writing, so we
1295 * only fault if they try to write with some invalid bar/offset/length.
1296 */
1297static bool valid_bar_access(struct device *d,
1298                             struct virtio_pci_cfg_cap_u32 *cfg_access)
1299{
1300        /* We only have 1 bar (BAR0) */
1301        if (cfg_access->cap.bar != 0)
1302                return false;
1303
1304        /* Check it's within BAR0. */
1305        if (cfg_access->cap.offset >= d->mmio_size
1306            || cfg_access->cap.offset + cfg_access->cap.length > d->mmio_size)
1307                return false;
1308
1309        /* Check length is 1, 2 or 4. */
1310        if (cfg_access->cap.length != 1
1311            && cfg_access->cap.length != 2
1312            && cfg_access->cap.length != 4)
1313                return false;
1314
1315        /*
1316         * 4.1.4.7.2:
1317         *
1318         *  The driver MUST NOT write a cap.offset which is not a multiple of
1319         *  cap.length (ie. all accesses MUST be aligned).
1320         */
1321        if (cfg_access->cap.offset % cfg_access->cap.length != 0)
1322                return false;
1323
1324        /* Return pointer into word in BAR0. */
1325        return true;
1326}
1327
1328/* Is this accessing the PCI config address port?. */
1329static bool is_pci_addr_port(u16 port)
1330{
1331        return port >= PCI_CONFIG_ADDR && port < PCI_CONFIG_ADDR + 4;
1332}
1333
1334static bool pci_addr_iowrite(u16 port, u32 mask, u32 val)
1335{
1336        iowrite(port - PCI_CONFIG_ADDR, val, mask,
1337                &pci_config_addr.val);
1338        verbose("PCI%s: %#x/%x: bus %u dev %u func %u reg %u\n",
1339                pci_config_addr.bits.enabled ? "" : " DISABLED",
1340                val, mask,
1341                pci_config_addr.bits.busnum,
1342                pci_config_addr.bits.devnum,
1343                pci_config_addr.bits.funcnum,
1344                pci_config_addr.bits.offset);
1345        return true;
1346}
1347
1348static void pci_addr_ioread(u16 port, u32 mask, u32 *val)
1349{
1350        ioread(port - PCI_CONFIG_ADDR, pci_config_addr.val, mask, val);
1351}
1352
1353/* Is this accessing the PCI config data port?. */
1354static bool is_pci_data_port(u16 port)
1355{
1356        return port >= PCI_CONFIG_DATA && port < PCI_CONFIG_DATA + 4;
1357}
1358
1359static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask);
1360
1361static bool pci_data_iowrite(u16 port, u32 mask, u32 val)
1362{
1363        u32 reg, portoff;
1364        struct device *d = dev_and_reg(&reg);
1365
1366        /* Complain if they don't belong to a device. */
1367        if (!d)
1368                return false;
1369
1370        /* They can do 1 byte writes, etc. */
1371        portoff = port - PCI_CONFIG_DATA;
1372
1373        /*
1374         * PCI uses a weird way to determine the BAR size: the OS
1375         * writes all 1's, and sees which ones stick.
1376         */
1377        if (&d->config_words[reg] == &d->config.bar[0]) {
1378                int i;
1379
1380                iowrite(portoff, val, mask, &d->config.bar[0]);
1381                for (i = 0; (1 << i) < d->mmio_size; i++)
1382                        d->config.bar[0] &= ~(1 << i);
1383                return true;
1384        } else if ((&d->config_words[reg] > &d->config.bar[0]
1385                    && &d->config_words[reg] <= &d->config.bar[6])
1386                   || &d->config_words[reg] == &d->config.expansion_rom_addr) {
1387                /* Allow writing to any other BAR, or expansion ROM */
1388                iowrite(portoff, val, mask, &d->config_words[reg]);
1389                return true;
1390                /* We let them overide latency timer and cacheline size */
1391        } else if (&d->config_words[reg] == (void *)&d->config.cacheline_size) {
1392                /* Only let them change the first two fields. */
1393                if (mask == 0xFFFFFFFF)
1394                        mask = 0xFFFF;
1395                iowrite(portoff, val, mask, &d->config_words[reg]);
1396                return true;
1397        } else if (&d->config_words[reg] == (void *)&d->config.command
1398                   && mask == 0xFFFF) {
1399                /* Ignore command writes. */
1400                return true;
1401        } else if (&d->config_words[reg]
1402                   == (void *)&d->config.cfg_access.cap.bar
1403                   || &d->config_words[reg]
1404                   == &d->config.cfg_access.cap.length
1405                   || &d->config_words[reg]
1406                   == &d->config.cfg_access.cap.offset) {
1407
1408                /*
1409                 * The VIRTIO_PCI_CAP_PCI_CFG capability
1410                 * provides a backdoor to access the MMIO
1411                 * regions without mapping them.  Weird, but
1412                 * useful.
1413                 */
1414                iowrite(portoff, val, mask, &d->config_words[reg]);
1415                return true;
1416        } else if (&d->config_words[reg] == &d->config.cfg_access.pci_cfg_data) {
1417                u32 write_mask;
1418
1419                /*
1420                 * 4.1.4.7.1:
1421                 *
1422                 *  Upon detecting driver write access to pci_cfg_data, the
1423                 *  device MUST execute a write access at offset cap.offset at
1424                 *  BAR selected by cap.bar using the first cap.length bytes
1425                 *  from pci_cfg_data.
1426                 */
1427
1428                /* Must be bar 0 */
1429                if (!valid_bar_access(d, &d->config.cfg_access))
1430                        return false;
1431
1432                iowrite(portoff, val, mask, &d->config.cfg_access.pci_cfg_data);
1433
1434                /*
1435                 * Now emulate a write.  The mask we use is set by
1436                 * len, *not* this write!
1437                 */
1438                write_mask = (1ULL<<(8*d->config.cfg_access.cap.length)) - 1;
1439                verbose("Window writing %#x/%#x to bar %u, offset %u len %u\n",
1440                        d->config.cfg_access.pci_cfg_data, write_mask,
1441                        d->config.cfg_access.cap.bar,
1442                        d->config.cfg_access.cap.offset,
1443                        d->config.cfg_access.cap.length);
1444
1445                emulate_mmio_write(d, d->config.cfg_access.cap.offset,
1446                                   d->config.cfg_access.pci_cfg_data,
1447                                   write_mask);
1448                return true;
1449        }
1450
1451        /*
1452         * 4.1.4.1:
1453         *
1454         *  The driver MUST NOT write into any field of the capability
1455         *  structure, with the exception of those with cap_type
1456         *  VIRTIO_PCI_CAP_PCI_CFG...
1457         */
1458        return false;
1459}
1460
1461static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask);
1462
1463static void pci_data_ioread(u16 port, u32 mask, u32 *val)
1464{
1465        u32 reg;
1466        struct device *d = dev_and_reg(&reg);
1467
1468        if (!d)
1469                return;
1470
1471        /* Read through the PCI MMIO access window is special */
1472        if (&d->config_words[reg] == &d->config.cfg_access.pci_cfg_data) {
1473                u32 read_mask;
1474
1475                /*
1476                 * 4.1.4.7.1:
1477                 *
1478                 *  Upon detecting driver read access to pci_cfg_data, the
1479                 *  device MUST execute a read access of length cap.length at
1480                 *  offset cap.offset at BAR selected by cap.bar and store the
1481                 *  first cap.length bytes in pci_cfg_data.
1482                 */
1483                /* Must be bar 0 */
1484                if (!valid_bar_access(d, &d->config.cfg_access))
1485                        bad_driver(d,
1486                             "Invalid cfg_access to bar%u, offset %u len %u",
1487                             d->config.cfg_access.cap.bar,
1488                             d->config.cfg_access.cap.offset,
1489                             d->config.cfg_access.cap.length);
1490
1491                /*
1492                 * Read into the window.  The mask we use is set by
1493                 * len, *not* this read!
1494                 */
1495                read_mask = (1ULL<<(8*d->config.cfg_access.cap.length))-1;
1496                d->config.cfg_access.pci_cfg_data
1497                        = emulate_mmio_read(d,
1498                                            d->config.cfg_access.cap.offset,
1499                                            read_mask);
1500                verbose("Window read %#x/%#x from bar %u, offset %u len %u\n",
1501                        d->config.cfg_access.pci_cfg_data, read_mask,
1502                        d->config.cfg_access.cap.bar,
1503                        d->config.cfg_access.cap.offset,
1504                        d->config.cfg_access.cap.length);
1505        }
1506        ioread(port - PCI_CONFIG_DATA, d->config_words[reg], mask, val);
1507}
1508
1509/*L:216
1510 * This is where we emulate a handful of Guest instructions.  It's ugly
1511 * and we used to do it in the kernel but it grew over time.
1512 */
1513
1514/*
1515 * We use the ptrace syscall's pt_regs struct to talk about registers
1516 * to lguest: these macros convert the names to the offsets.
1517 */
1518#define getreg(name) getreg_off(offsetof(struct user_regs_struct, name))
1519#define setreg(name, val) \
1520        setreg_off(offsetof(struct user_regs_struct, name), (val))
1521
1522static u32 getreg_off(size_t offset)
1523{
1524        u32 r;
1525        unsigned long args[] = { LHREQ_GETREG, offset };
1526
1527        if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0)
1528                err(1, "Getting register %u", offset);
1529        if (pread(lguest_fd, &r, sizeof(r), cpu_id) != sizeof(r))
1530                err(1, "Reading register %u", offset);
1531
1532        return r;
1533}
1534
1535static void setreg_off(size_t offset, u32 val)
1536{
1537        unsigned long args[] = { LHREQ_SETREG, offset, val };
1538
1539        if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0)
1540                err(1, "Setting register %u", offset);
1541}
1542
1543/* Get register by instruction encoding */
1544static u32 getreg_num(unsigned regnum, u32 mask)
1545{
1546        /* 8 bit ops use regnums 4-7 for high parts of word */
1547        if (mask == 0xFF && (regnum & 0x4))
1548                return getreg_num(regnum & 0x3, 0xFFFF) >> 8;
1549
1550        switch (regnum) {
1551        case 0: return getreg(eax) & mask;
1552        case 1: return getreg(ecx) & mask;
1553        case 2: return getreg(edx) & mask;
1554        case 3: return getreg(ebx) & mask;
1555        case 4: return getreg(esp) & mask;
1556        case 5: return getreg(ebp) & mask;
1557        case 6: return getreg(esi) & mask;
1558        case 7: return getreg(edi) & mask;
1559        }
1560        abort();
1561}
1562
1563/* Set register by instruction encoding */
1564static void setreg_num(unsigned regnum, u32 val, u32 mask)
1565{
1566        /* Don't try to set bits out of range */
1567        assert(~(val & ~mask));
1568
1569        /* 8 bit ops use regnums 4-7 for high parts of word */
1570        if (mask == 0xFF && (regnum & 0x4)) {
1571                /* Construct the 16 bits we want. */
1572                val = (val << 8) | getreg_num(regnum & 0x3, 0xFF);
1573                setreg_num(regnum & 0x3, val, 0xFFFF);
1574                return;
1575        }
1576
1577        switch (regnum) {
1578        case 0: setreg(eax, val | (getreg(eax) & ~mask)); return;
1579        case 1: setreg(ecx, val | (getreg(ecx) & ~mask)); return;
1580        case 2: setreg(edx, val | (getreg(edx) & ~mask)); return;
1581        case 3: setreg(ebx, val | (getreg(ebx) & ~mask)); return;
1582        case 4: setreg(esp, val | (getreg(esp) & ~mask)); return;
1583        case 5: setreg(ebp, val | (getreg(ebp) & ~mask)); return;
1584        case 6: setreg(esi, val | (getreg(esi) & ~mask)); return;
1585        case 7: setreg(edi, val | (getreg(edi) & ~mask)); return;
1586        }
1587        abort();
1588}
1589
1590/* Get bytes of displacement appended to instruction, from r/m encoding */
1591static u32 insn_displacement_len(u8 mod_reg_rm)
1592{
1593        /* Switch on the mod bits */
1594        switch (mod_reg_rm >> 6) {
1595        case 0:
1596                /* If mod == 0, and r/m == 101, 16-bit displacement follows */
1597                if ((mod_reg_rm & 0x7) == 0x5)
1598                        return 2;
1599                /* Normally, mod == 0 means no literal displacement */
1600                return 0;
1601        case 1:
1602                /* One byte displacement */
1603                return 1;
1604        case 2:
1605                /* Four byte displacement */
1606                return 4;
1607        case 3:
1608                /* Register mode */
1609                return 0;
1610        }
1611        abort();
1612}
1613
1614static void emulate_insn(const u8 insn[])
1615{
1616        unsigned long args[] = { LHREQ_TRAP, 13 };
1617        unsigned int insnlen = 0, in = 0, small_operand = 0, byte_access;
1618        unsigned int eax, port, mask;
1619        /*
1620         * Default is to return all-ones on IO port reads, which traditionally
1621         * means "there's nothing there".
1622         */
1623        u32 val = 0xFFFFFFFF;
1624
1625        /*
1626         * This must be the Guest kernel trying to do something, not userspace!
1627         * The bottom two bits of the CS segment register are the privilege
1628         * level.
1629         */
1630        if ((getreg(xcs) & 3) != 0x1)
1631                goto no_emulate;
1632
1633        /* Decoding x86 instructions is icky. */
1634
1635        /*
1636         * Around 2.6.33, the kernel started using an emulation for the
1637         * cmpxchg8b instruction in early boot on many configurations.  This
1638         * code isn't paravirtualized, and it tries to disable interrupts.
1639         * Ignore it, which will Mostly Work.
1640         */
1641        if (insn[insnlen] == 0xfa) {
1642                /* "cli", or Clear Interrupt Enable instruction.  Skip it. */
1643                insnlen = 1;
1644                goto skip_insn;
1645        }
1646
1647        /*
1648         * 0x66 is an "operand prefix".  It means a 16, not 32 bit in/out.
1649         */
1650        if (insn[insnlen] == 0x66) {
1651                small_operand = 1;
1652                /* The instruction is 1 byte so far, read the next byte. */
1653                insnlen = 1;
1654        }
1655
1656        /* If the lower bit isn't set, it's a single byte access */
1657        byte_access = !(insn[insnlen] & 1);
1658
1659        /*
1660         * Now we can ignore the lower bit and decode the 4 opcodes
1661         * we need to emulate.
1662         */
1663        switch (insn[insnlen] & 0xFE) {
1664        case 0xE4: /* in     <next byte>,%al */
1665                port = insn[insnlen+1];
1666                insnlen += 2;
1667                in = 1;
1668                break;
1669        case 0xEC: /* in     (%dx),%al */
1670                port = getreg(edx) & 0xFFFF;
1671                insnlen += 1;
1672                in = 1;
1673                break;
1674        case 0xE6: /* out    %al,<next byte> */
1675                port = insn[insnlen+1];
1676                insnlen += 2;
1677                break;
1678        case 0xEE: /* out    %al,(%dx) */
1679                port = getreg(edx) & 0xFFFF;
1680                insnlen += 1;
1681                break;
1682        default:
1683                /* OK, we don't know what this is, can't emulate. */
1684                goto no_emulate;
1685        }
1686
1687        /* Set a mask of the 1, 2 or 4 bytes, depending on size of IO */
1688        if (byte_access)
1689                mask = 0xFF;
1690        else if (small_operand)
1691                mask = 0xFFFF;
1692        else
1693                mask = 0xFFFFFFFF;
1694
1695        /*
1696         * If it was an "IN" instruction, they expect the result to be read
1697         * into %eax, so we change %eax.
1698         */
1699        eax = getreg(eax);
1700
1701        if (in) {
1702                /* This is the PS/2 keyboard status; 1 means ready for output */
1703                if (port == 0x64)
1704                        val = 1;
1705                else if (is_pci_addr_port(port))
1706                        pci_addr_ioread(port, mask, &val);
1707                else if (is_pci_data_port(port))
1708                        pci_data_ioread(port, mask, &val);
1709
1710                /* Clear the bits we're about to read */
1711                eax &= ~mask;
1712                /* Copy bits in from val. */
1713                eax |= val & mask;
1714                /* Now update the register. */
1715                setreg(eax, eax);
1716        } else {
1717                if (is_pci_addr_port(port)) {
1718                        if (!pci_addr_iowrite(port, mask, eax))
1719                                goto bad_io;
1720                } else if (is_pci_data_port(port)) {
1721                        if (!pci_data_iowrite(port, mask, eax))
1722                                goto bad_io;
1723                }
1724                /* There are many other ports, eg. CMOS clock, serial
1725                 * and parallel ports, so we ignore them all. */
1726        }
1727
1728        verbose("IO %s of %x to %u: %#08x\n",
1729                in ? "IN" : "OUT", mask, port, eax);
1730skip_insn:
1731        /* Finally, we've "done" the instruction, so move past it. */
1732        setreg(eip, getreg(eip) + insnlen);
1733        return;
1734
1735bad_io:
1736        warnx("Attempt to %s port %u (%#x mask)",
1737              in ? "read from" : "write to", port, mask);
1738
1739no_emulate:
1740        /* Inject trap into Guest. */
1741        if (write(lguest_fd, args, sizeof(args)) < 0)
1742                err(1, "Reinjecting trap 13 for fault at %#x", getreg(eip));
1743}
1744
1745static struct device *find_mmio_region(unsigned long paddr, u32 *off)
1746{
1747        unsigned int i;
1748
1749        for (i = 1; i < MAX_PCI_DEVICES; i++) {
1750                struct device *d = devices.pci[i];
1751
1752                if (!d)
1753                        continue;
1754                if (paddr < d->mmio_addr)
1755                        continue;
1756                if (paddr >= d->mmio_addr + d->mmio_size)
1757                        continue;
1758                *off = paddr - d->mmio_addr;
1759                return d;
1760        }
1761        return NULL;
1762}
1763
1764/* FIXME: Use vq array. */
1765static struct virtqueue *vq_by_num(struct device *d, u32 num)
1766{
1767        struct virtqueue *vq = d->vq;
1768
1769        while (num-- && vq)
1770                vq = vq->next;
1771
1772        return vq;
1773}
1774
1775static void save_vq_config(const struct virtio_pci_common_cfg *cfg,
1776                           struct virtqueue *vq)
1777{
1778        vq->pci_config = *cfg;
1779}
1780
1781static void restore_vq_config(struct virtio_pci_common_cfg *cfg,
1782                              struct virtqueue *vq)
1783{
1784        /* Only restore the per-vq part */
1785        size_t off = offsetof(struct virtio_pci_common_cfg, queue_size);
1786
1787        memcpy((void *)cfg + off, (void *)&vq->pci_config + off,
1788               sizeof(*cfg) - off);
1789}
1790
1791/*
1792 * 4.1.4.3.2:
1793 *
1794 *  The driver MUST configure the other virtqueue fields before
1795 *  enabling the virtqueue with queue_enable.
1796 *
1797 * When they enable the virtqueue, we check that their setup is valid.
1798 */
1799static void check_virtqueue(struct device *d, struct virtqueue *vq)
1800{
1801        /* Because lguest is 32 bit, all the descriptor high bits must be 0 */
1802        if (vq->pci_config.queue_desc_hi
1803            || vq->pci_config.queue_avail_hi
1804            || vq->pci_config.queue_used_hi)
1805                bad_driver_vq(vq, "invalid 64-bit queue address");
1806
1807        /*
1808         * 2.4.1:
1809         *
1810         *  The driver MUST ensure that the physical address of the first byte
1811         *  of each virtqueue part is a multiple of the specified alignment
1812         *  value in the above table.
1813         */
1814        if (vq->pci_config.queue_desc_lo % 16
1815            || vq->pci_config.queue_avail_lo % 2
1816            || vq->pci_config.queue_used_lo % 4)
1817                bad_driver_vq(vq, "invalid alignment in queue addresses");
1818
1819        /* Initialize the virtqueue and check they're all in range. */
1820        vq->vring.num = vq->pci_config.queue_size;
1821        vq->vring.desc = check_pointer(vq->dev,
1822                                       vq->pci_config.queue_desc_lo,
1823                                       sizeof(*vq->vring.desc) * vq->vring.num);
1824        vq->vring.avail = check_pointer(vq->dev,
1825                                        vq->pci_config.queue_avail_lo,
1826                                        sizeof(*vq->vring.avail)
1827                                        + (sizeof(vq->vring.avail->ring[0])
1828                                           * vq->vring.num));
1829        vq->vring.used = check_pointer(vq->dev,
1830                                       vq->pci_config.queue_used_lo,
1831                                       sizeof(*vq->vring.used)
1832                                       + (sizeof(vq->vring.used->ring[0])
1833                                          * vq->vring.num));
1834
1835        /*
1836         * 2.4.9.1:
1837         *
1838         *   The driver MUST initialize flags in the used ring to 0
1839         *   when allocating the used ring.
1840         */
1841        if (vq->vring.used->flags != 0)
1842                bad_driver_vq(vq, "invalid initial used.flags %#x",
1843                              vq->vring.used->flags);
1844}
1845
1846static void start_virtqueue(struct virtqueue *vq)
1847{
1848        /*
1849         * Create stack for thread.  Since the stack grows upwards, we point
1850         * the stack pointer to the end of this region.
1851         */
1852        char *stack = malloc(32768);
1853
1854        /* Create a zero-initialized eventfd. */
1855        vq->eventfd = eventfd(0, 0);
1856        if (vq->eventfd < 0)
1857                err(1, "Creating eventfd");
1858
1859        /*
1860         * CLONE_VM: because it has to access the Guest memory, and SIGCHLD so
1861         * we get a signal if it dies.
1862         */
1863        vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq);
1864        if (vq->thread == (pid_t)-1)
1865                err(1, "Creating clone");
1866}
1867
1868static void start_virtqueues(struct device *d)
1869{
1870        struct virtqueue *vq;
1871
1872        for (vq = d->vq; vq; vq = vq->next) {
1873                if (vq->pci_config.queue_enable)
1874                        start_virtqueue(vq);
1875        }
1876}
1877
1878static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
1879{
1880        struct virtqueue *vq;
1881
1882        switch (off) {
1883        case offsetof(struct virtio_pci_mmio, cfg.device_feature_select):
1884                /*
1885                 * 4.1.4.3.1:
1886                 *
1887                 * The device MUST present the feature bits it is offering in
1888                 * device_feature, starting at bit device_feature_select ∗ 32
1889                 * for any device_feature_select written by the driver
1890                 */
1891                if (val == 0)
1892                        d->mmio->cfg.device_feature = d->features;
1893                else if (val == 1)
1894                        d->mmio->cfg.device_feature = (d->features >> 32);
1895                else
1896                        d->mmio->cfg.device_feature = 0;
1897                goto feature_write_through32;
1898        case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select):
1899                if (val > 1)
1900                        bad_driver(d, "Unexpected driver select %u", val);
1901                goto feature_write_through32;
1902        case offsetof(struct virtio_pci_mmio, cfg.guest_feature):
1903                if (d->mmio->cfg.guest_feature_select == 0) {
1904                        d->features_accepted &= ~((u64)0xFFFFFFFF);
1905                        d->features_accepted |= val;
1906                } else {
1907                        assert(d->mmio->cfg.guest_feature_select == 1);
1908                        d->features_accepted &= 0xFFFFFFFF;
1909                        d->features_accepted |= ((u64)val) << 32;
1910                }
1911                /*
1912                 * 2.2.1:
1913                 *
1914                 *   The driver MUST NOT accept a feature which the device did
1915                 *   not offer
1916                 */
1917                if (d->features_accepted & ~d->features)
1918                        bad_driver(d, "over-accepted features %#llx of %#llx",
1919                                   d->features_accepted, d->features);
1920                goto feature_write_through32;
1921        case offsetof(struct virtio_pci_mmio, cfg.device_status): {
1922                u8 prev;
1923
1924                verbose("%s: device status -> %#x\n", d->name, val);
1925                /*
1926                 * 4.1.4.3.1:
1927                 * 
1928                 *  The device MUST reset when 0 is written to device_status,
1929                 *  and present a 0 in device_status once that is done.
1930                 */
1931                if (val == 0) {
1932                        reset_device(d);
1933                        goto write_through8;
1934                }
1935
1936                /* 2.1.1: The driver MUST NOT clear a device status bit. */
1937                if (d->mmio->cfg.device_status & ~val)
1938                        bad_driver(d, "unset of device status bit %#x -> %#x",
1939                                   d->mmio->cfg.device_status, val);
1940
1941                /*
1942                 * 2.1.2:
1943                 *
1944                 *  The device MUST NOT consume buffers or notify the driver
1945                 *  before DRIVER_OK.
1946                 */
1947                if (val & VIRTIO_CONFIG_S_DRIVER_OK
1948                    && !(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK))
1949                        start_virtqueues(d);
1950
1951                /*
1952                 * 3.1.1:
1953                 *
1954                 *   The driver MUST follow this sequence to initialize a device:
1955                 *   - Reset the device.
1956                 *   - Set the ACKNOWLEDGE status bit: the guest OS has
1957                 *     notice the device.
1958                 *   - Set the DRIVER status bit: the guest OS knows how
1959                 *     to drive the device.
1960                 *   - Read device feature bits, and write the subset
1961                 *     of feature bits understood by the OS and driver
1962                 *     to the device. During this step the driver MAY
1963                 *     read (but MUST NOT write) the device-specific
1964                 *     configuration fields to check that it can
1965                 *     support the device before accepting it.
1966                 *   - Set the FEATURES_OK status bit.  The driver
1967                 *     MUST not accept new feature bits after this
1968                 *     step.
1969                 *   - Re-read device status to ensure the FEATURES_OK
1970                 *     bit is still set: otherwise, the device does
1971                 *     not support our subset of features and the
1972                 *     device is unusable.
1973                 *   - Perform device-specific setup, including
1974                 *     discovery of virtqueues for the device,
1975                 *     optional per-bus setup, reading and possibly
1976                 *     writing the device’s virtio configuration
1977                 *     space, and population of virtqueues.
1978                 *   - Set the DRIVER_OK status bit. At this point the
1979                 *     device is “live”.
1980                 */
1981                prev = 0;
1982                switch (val & ~d->mmio->cfg.device_status) {
1983                case VIRTIO_CONFIG_S_DRIVER_OK:
1984                        prev |= VIRTIO_CONFIG_S_FEATURES_OK; /* fall thru */
1985                case VIRTIO_CONFIG_S_FEATURES_OK:
1986                        prev |= VIRTIO_CONFIG_S_DRIVER; /* fall thru */
1987                case VIRTIO_CONFIG_S_DRIVER:
1988                        prev |= VIRTIO_CONFIG_S_ACKNOWLEDGE; /* fall thru */
1989                case VIRTIO_CONFIG_S_ACKNOWLEDGE:
1990                        break;
1991                default:
1992                        bad_driver(d, "unknown device status bit %#x -> %#x",
1993                                   d->mmio->cfg.device_status, val);
1994                }
1995                if (d->mmio->cfg.device_status != prev)
1996                        bad_driver(d, "unexpected status transition %#x -> %#x",
1997                                   d->mmio->cfg.device_status, val);
1998
1999                /* If they just wrote FEATURES_OK, we make sure they read */
2000                switch (val & ~d->mmio->cfg.device_status) {
2001                case VIRTIO_CONFIG_S_FEATURES_OK:
2002                        d->wrote_features_ok = true;
2003                        break;
2004                case VIRTIO_CONFIG_S_DRIVER_OK:
2005                        if (d->wrote_features_ok)
2006                                bad_driver(d, "did not re-read FEATURES_OK");
2007                        break;
2008                }
2009                goto write_through8;
2010        }
2011        case offsetof(struct virtio_pci_mmio, cfg.queue_select):
2012                vq = vq_by_num(d, val);
2013                /*
2014                 * 4.1.4.3.1:
2015                 *
2016                 *  The device MUST present a 0 in queue_size if the virtqueue
2017                 *  corresponding to the current queue_select is unavailable.
2018                 */
2019                if (!vq) {
2020                        d->mmio->cfg.queue_size = 0;
2021                        goto write_through16;
2022                }
2023                /* Save registers for old vq, if it was a valid vq */
2024                if (d->mmio->cfg.queue_size)
2025                        save_vq_config(&d->mmio->cfg,
2026                                       vq_by_num(d, d->mmio->cfg.queue_select));
2027                /* Restore the registers for the queue they asked for */
2028                restore_vq_config(&d->mmio->cfg, vq);
2029                goto write_through16;
2030        case offsetof(struct virtio_pci_mmio, cfg.queue_size):
2031                /*
2032                 * 4.1.4.3.2:
2033                 *
2034                 *  The driver MUST NOT write a value which is not a power of 2
2035                 *  to queue_size.
2036                 */
2037                if (val & (val-1))
2038                        bad_driver(d, "invalid queue size %u", val);
2039                if (d->mmio->cfg.queue_enable)
2040                        bad_driver(d, "changing queue size on live device");
2041                goto write_through16;
2042        case offsetof(struct virtio_pci_mmio, cfg.queue_msix_vector):
2043                bad_driver(d, "attempt to set MSIX vector to %u", val);
2044        case offsetof(struct virtio_pci_mmio, cfg.queue_enable): {
2045                struct virtqueue *vq = vq_by_num(d, d->mmio->cfg.queue_select);
2046
2047                /*
2048                 * 4.1.4.3.2:
2049                 *
2050                 *  The driver MUST NOT write a 0 to queue_enable.
2051                 */
2052                if (val != 1)
2053                        bad_driver(d, "setting queue_enable to %u", val);
2054
2055                /*
2056                 * 3.1.1:
2057                 *
2058                 *  7. Perform device-specific setup, including discovery of
2059                 *     virtqueues for the device, optional per-bus setup,
2060                 *     reading and possibly writing the device’s virtio
2061                 *     configuration space, and population of virtqueues.
2062                 *  8. Set the DRIVER_OK status bit.
2063                 *
2064                 * All our devices require all virtqueues to be enabled, so
2065                 * they should have done that before setting DRIVER_OK.
2066                 */
2067                if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK)
2068                        bad_driver(d, "enabling vq after DRIVER_OK");
2069
2070                d->mmio->cfg.queue_enable = val;
2071                save_vq_config(&d->mmio->cfg, vq);
2072                check_virtqueue(d, vq);
2073                goto write_through16;
2074        }
2075        case offsetof(struct virtio_pci_mmio, cfg.queue_notify_off):
2076                bad_driver(d, "attempt to write to queue_notify_off");
2077        case offsetof(struct virtio_pci_mmio, cfg.queue_desc_lo):
2078        case offsetof(struct virtio_pci_mmio, cfg.queue_desc_hi):
2079        case offsetof(struct virtio_pci_mmio, cfg.queue_avail_lo):
2080        case offsetof(struct virtio_pci_mmio, cfg.queue_avail_hi):
2081        case offsetof(struct virtio_pci_mmio, cfg.queue_used_lo):
2082        case offsetof(struct virtio_pci_mmio, cfg.queue_used_hi):
2083                /*
2084                 * 4.1.4.3.2:
2085                 *
2086                 *  The driver MUST configure the other virtqueue fields before
2087                 *  enabling the virtqueue with queue_enable.
2088                 */
2089                if (d->mmio->cfg.queue_enable)
2090                        bad_driver(d, "changing queue on live device");
2091
2092                /*
2093                 * 3.1.1:
2094                 *
2095                 *  The driver MUST follow this sequence to initialize a device:
2096                 *...
2097                 *  5. Set the FEATURES_OK status bit. The driver MUST not
2098                 *  accept new feature bits after this step.
2099                 */
2100                if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK))
2101                        bad_driver(d, "setting up vq before FEATURES_OK");
2102
2103                /*
2104                 *  6. Re-read device status to ensure the FEATURES_OK bit is
2105                 *     still set...
2106                 */
2107                if (d->wrote_features_ok)
2108                        bad_driver(d, "didn't re-read FEATURES_OK before setup");
2109
2110                goto write_through32;
2111        case offsetof(struct virtio_pci_mmio, notify):
2112                vq = vq_by_num(d, val);
2113                if (!vq)
2114                        bad_driver(d, "Invalid vq notification on %u", val);
2115                /* Notify the process handling this vq by adding 1 to eventfd */
2116                write(vq->eventfd, "\1\0\0\0\0\0\0\0", 8);
2117                goto write_through16;
2118        case offsetof(struct virtio_pci_mmio, isr):
2119                bad_driver(d, "Unexpected write to isr");
2120        /* Weird corner case: write to emerg_wr of console */
2121        case sizeof(struct virtio_pci_mmio)
2122                + offsetof(struct virtio_console_config, emerg_wr):
2123                if (strcmp(d->name, "console") == 0) {
2124                        char c = val;
2125                        write(STDOUT_FILENO, &c, 1);
2126                        goto write_through32;
2127                }
2128                /* Fall through... */
2129        default:
2130                /*
2131                 * 4.1.4.3.2:
2132                 *
2133                 *   The driver MUST NOT write to device_feature, num_queues,
2134                 *   config_generation or queue_notify_off.
2135                 */
2136                bad_driver(d, "Unexpected write to offset %u", off);
2137        }
2138
2139feature_write_through32:
2140        /*
2141         * 3.1.1:
2142         *
2143         *   The driver MUST follow this sequence to initialize a device:
2144         *...
2145         *   - Set the DRIVER status bit: the guest OS knows how
2146         *     to drive the device.
2147         *   - Read device feature bits, and write the subset
2148         *     of feature bits understood by the OS and driver
2149         *     to the device.
2150         *...
2151         *   - Set the FEATURES_OK status bit. The driver MUST not
2152         *     accept new feature bits after this step.
2153         */
2154        if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
2155                bad_driver(d, "feature write before VIRTIO_CONFIG_S_DRIVER");
2156        if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK)
2157                bad_driver(d, "feature write after VIRTIO_CONFIG_S_FEATURES_OK");
2158
2159        /*
2160         * 4.1.3.1:
2161         *
2162         *  The driver MUST access each field using the “natural” access
2163         *  method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for
2164         *  16-bit fields and 8-bit accesses for 8-bit fields.
2165         */
2166write_through32:
2167        if (mask != 0xFFFFFFFF) {
2168                bad_driver(d, "non-32-bit write to offset %u (%#x)",
2169                           off, getreg(eip));
2170                return;
2171        }
2172        memcpy((char *)d->mmio + off, &val, 4);
2173        return;
2174
2175write_through16:
2176        if (mask != 0xFFFF)
2177                bad_driver(d, "non-16-bit write to offset %u (%#x)",
2178                           off, getreg(eip));
2179        memcpy((char *)d->mmio + off, &val, 2);
2180        return;
2181
2182write_through8:
2183        if (mask != 0xFF)
2184                bad_driver(d, "non-8-bit write to offset %u (%#x)",
2185                           off, getreg(eip));
2186        memcpy((char *)d->mmio + off, &val, 1);
2187        return;
2188}
2189
2190static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask)
2191{
2192        u8 isr;
2193        u32 val = 0;
2194
2195        switch (off) {
2196        case offsetof(struct virtio_pci_mmio, cfg.device_feature_select):
2197        case offsetof(struct virtio_pci_mmio, cfg.device_feature):
2198        case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select):
2199        case offsetof(struct virtio_pci_mmio, cfg.guest_feature):
2200                /*
2201                 * 3.1.1:
2202                 *
2203                 *   The driver MUST follow this sequence to initialize a device:
2204                 *...
2205                 *   - Set the DRIVER status bit: the guest OS knows how
2206                 *     to drive the device.
2207                 *   - Read device feature bits, and write the subset
2208                 *     of feature bits understood by the OS and driver
2209                 *     to the device.
2210                 */
2211                if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
2212                        bad_driver(d,
2213                                   "feature read before VIRTIO_CONFIG_S_DRIVER");
2214                goto read_through32;
2215        case offsetof(struct virtio_pci_mmio, cfg.msix_config):
2216                bad_driver(d, "read of msix_config");
2217        case offsetof(struct virtio_pci_mmio, cfg.num_queues):
2218                goto read_through16;
2219        case offsetof(struct virtio_pci_mmio, cfg.device_status):
2220                /* As they did read, any write of FEATURES_OK is now fine. */
2221                d->wrote_features_ok = false;
2222                goto read_through8;
2223        case offsetof(struct virtio_pci_mmio, cfg.config_generation):
2224                /*
2225                 * 4.1.4.3.1:
2226                 *
2227                 *  The device MUST present a changed config_generation after
2228                 *  the driver has read a device-specific configuration value
2229                 *  which has changed since any part of the device-specific
2230                 *  configuration was last read.
2231                 *
2232                 * This is simple: none of our devices change config, so this
2233                 * is always 0.
2234                 */
2235                goto read_through8;
2236        case offsetof(struct virtio_pci_mmio, notify):
2237                /*
2238                 * 3.1.1:
2239                 *
2240                 *   The driver MUST NOT notify the device before setting
2241                 *   DRIVER_OK.
2242                 */
2243                if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK))
2244                        bad_driver(d, "notify before VIRTIO_CONFIG_S_DRIVER_OK");
2245                goto read_through16;
2246        case offsetof(struct virtio_pci_mmio, isr):
2247                if (mask != 0xFF)
2248                        bad_driver(d, "non-8-bit read from offset %u (%#x)",
2249                                   off, getreg(eip));
2250                isr = d->mmio->isr;
2251                /*
2252                 * 4.1.4.5.1:
2253                 *
2254                 *  The device MUST reset ISR status to 0 on driver read. 
2255                 */
2256                d->mmio->isr = 0;
2257                return isr;
2258        case offsetof(struct virtio_pci_mmio, padding):
2259                bad_driver(d, "read from padding (%#x)", getreg(eip));
2260        default:
2261                /* Read from device config space, beware unaligned overflow */
2262                if (off > d->mmio_size - 4)
2263                        bad_driver(d, "read past end (%#x)", getreg(eip));
2264
2265                /*
2266                 * 3.1.1:
2267                 *  The driver MUST follow this sequence to initialize a device:
2268                 *...
2269                 *  3. Set the DRIVER status bit: the guest OS knows how to
2270                 *  drive the device.
2271                 *  4. Read device feature bits, and write the subset of
2272                 *  feature bits understood by the OS and driver to the
2273                 *  device. During this step the driver MAY read (but MUST NOT
2274                 *  write) the device-specific configuration fields to check
2275                 *  that it can support the device before accepting it.
2276                 */
2277                if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
2278                        bad_driver(d,
2279                                   "config read before VIRTIO_CONFIG_S_DRIVER");
2280
2281                if (mask == 0xFFFFFFFF)
2282                        goto read_through32;
2283                else if (mask == 0xFFFF)
2284                        goto read_through16;
2285                else
2286                        goto read_through8;
2287        }
2288
2289        /*
2290         * 4.1.3.1:
2291         *
2292         *  The driver MUST access each field using the “natural” access
2293         *  method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for
2294         *  16-bit fields and 8-bit accesses for 8-bit fields.
2295         */
2296read_through32:
2297        if (mask != 0xFFFFFFFF)
2298                bad_driver(d, "non-32-bit read to offset %u (%#x)",
2299                           off, getreg(eip));
2300        memcpy(&val, (char *)d->mmio + off, 4);
2301        return val;
2302
2303read_through16:
2304        if (mask != 0xFFFF)
2305                bad_driver(d, "non-16-bit read to offset %u (%#x)",
2306                           off, getreg(eip));
2307        memcpy(&val, (char *)d->mmio + off, 2);
2308        return val;
2309
2310read_through8:
2311        if (mask != 0xFF)
2312                bad_driver(d, "non-8-bit read to offset %u (%#x)",
2313                           off, getreg(eip));
2314        memcpy(&val, (char *)d->mmio + off, 1);
2315        return val;
2316}
2317
2318static void emulate_mmio(unsigned long paddr, const u8 *insn)
2319{
2320        u32 val, off, mask = 0xFFFFFFFF, insnlen = 0;
2321        struct device *d = find_mmio_region(paddr, &off);
2322        unsigned long args[] = { LHREQ_TRAP, 14 };
2323
2324        if (!d) {
2325                warnx("MMIO touching %#08lx (not a device)", paddr);
2326                goto reinject;
2327        }
2328
2329        /* Prefix makes it a 16 bit op */
2330        if (insn[0] == 0x66) {
2331                mask = 0xFFFF;
2332                insnlen++;
2333        }
2334
2335        /* iowrite */
2336        if (insn[insnlen] == 0x89) {
2337                /* Next byte is r/m byte: bits 3-5 are register. */
2338                val = getreg_num((insn[insnlen+1] >> 3) & 0x7, mask);
2339                emulate_mmio_write(d, off, val, mask);
2340                insnlen += 2 + insn_displacement_len(insn[insnlen+1]);
2341        } else if (insn[insnlen] == 0x8b) { /* ioread */
2342                /* Next byte is r/m byte: bits 3-5 are register. */
2343                val = emulate_mmio_read(d, off, mask);
2344                setreg_num((insn[insnlen+1] >> 3) & 0x7, val, mask);
2345                insnlen += 2 + insn_displacement_len(insn[insnlen+1]);
2346        } else if (insn[0] == 0x88) { /* 8-bit iowrite */
2347                mask = 0xff;
2348                /* Next byte is r/m byte: bits 3-5 are register. */
2349                val = getreg_num((insn[1] >> 3) & 0x7, mask);
2350                emulate_mmio_write(d, off, val, mask);
2351                insnlen = 2 + insn_displacement_len(insn[1]);
2352        } else if (insn[0] == 0x8a) { /* 8-bit ioread */
2353                mask = 0xff;
2354                val = emulate_mmio_read(d, off, mask);
2355                setreg_num((insn[1] >> 3) & 0x7, val, mask);
2356                insnlen = 2 + insn_displacement_len(insn[1]);
2357        } else {
2358                warnx("Unknown MMIO instruction touching %#08lx:"
2359                     " %02x %02x %02x %02x at %u",
2360                     paddr, insn[0], insn[1], insn[2], insn[3], getreg(eip));
2361        reinject:
2362                /* Inject trap into Guest. */
2363                if (write(lguest_fd, args, sizeof(args)) < 0)
2364                        err(1, "Reinjecting trap 14 for fault at %#x",
2365                            getreg(eip));
2366                return;
2367        }
2368
2369        /* Finally, we've "done" the instruction, so move past it. */
2370        setreg(eip, getreg(eip) + insnlen);
2371}
2372
2373/*L:190
2374 * Device Setup
2375 *
2376 * All devices need a descriptor so the Guest knows it exists, and a "struct
2377 * device" so the Launcher can keep track of it.  We have common helper
2378 * routines to allocate and manage them.
2379 */
2380static void add_pci_virtqueue(struct device *dev,
2381                              void (*service)(struct virtqueue *),
2382                              const char *name)
2383{
2384        struct virtqueue **i, *vq = malloc(sizeof(*vq));
2385
2386        /* Initialize the virtqueue */
2387        vq->next = NULL;
2388        vq->last_avail_idx = 0;
2389        vq->dev = dev;
2390        vq->name = name;
2391
2392        /*
2393         * This is the routine the service thread will run, and its Process ID
2394         * once it's running.
2395         */
2396        vq->service = service;
2397        vq->thread = (pid_t)-1;
2398
2399        /* Initialize the configuration. */
2400        reset_vq_pci_config(vq);
2401        vq->pci_config.queue_notify_off = 0;
2402
2403        /* Add one to the number of queues */
2404        vq->dev->mmio->cfg.num_queues++;
2405
2406        /*
2407         * Add to tail of list, so dev->vq is first vq, dev->vq->next is
2408         * second.
2409         */
2410        for (i = &dev->vq; *i; i = &(*i)->next);
2411        *i = vq;
2412}
2413
2414/* The Guest accesses the feature bits via the PCI common config MMIO region */
2415static void add_pci_feature(struct device *dev, unsigned bit)
2416{
2417        dev->features |= (1ULL << bit);
2418}
2419
2420/* For devices with no config. */
2421static void no_device_config(struct device *dev)
2422{
2423        dev->mmio_addr = get_mmio_region(dev->mmio_size);
2424
2425        dev->config.bar[0] = dev->mmio_addr;
2426        /* Bottom 4 bits must be zero */
2427        assert(~(dev->config.bar[0] & 0xF));
2428}
2429
2430/* This puts the device config into BAR0 */
2431static void set_device_config(struct device *dev, const void *conf, size_t len)
2432{
2433        /* Set up BAR 0 */
2434        dev->mmio_size += len;
2435        dev->mmio = realloc(dev->mmio, dev->mmio_size);
2436        memcpy(dev->mmio + 1, conf, len);
2437
2438        /*
2439         * 4.1.4.6:
2440         *
2441         *  The device MUST present at least one VIRTIO_PCI_CAP_DEVICE_CFG
2442         *  capability for any device type which has a device-specific
2443         *  configuration.
2444         */
2445        /* Hook up device cfg */
2446        dev->config.cfg_access.cap.cap_next
2447                = offsetof(struct pci_config, device);
2448
2449        /*
2450         * 4.1.4.6.1:
2451         *
2452         *  The offset for the device-specific configuration MUST be 4-byte
2453         *  aligned.
2454         */
2455        assert(dev->config.cfg_access.cap.cap_next % 4 == 0);
2456
2457        /* Fix up device cfg field length. */
2458        dev->config.device.length = len;
2459
2460        /* The rest is the same as the no-config case */
2461        no_device_config(dev);
2462}
2463
2464static void init_cap(struct virtio_pci_cap *cap, size_t caplen, int type,
2465                     size_t bar_offset, size_t bar_bytes, u8 next)
2466{
2467        cap->cap_vndr = PCI_CAP_ID_VNDR;
2468        cap->cap_next = next;
2469        cap->cap_len = caplen;
2470        cap->cfg_type = type;
2471        cap->bar = 0;
2472        memset(cap->padding, 0, sizeof(cap->padding));
2473        cap->offset = bar_offset;
2474        cap->length = bar_bytes;
2475}
2476
2477/*
2478 * This sets up the pci_config structure, as defined in the virtio 1.0
2479 * standard (and PCI standard).
2480 */
2481static void init_pci_config(struct pci_config *pci, u16 type,
2482                            u8 class, u8 subclass)
2483{
2484        size_t bar_offset, bar_len;
2485
2486        /*
2487         * 4.1.4.4.1:
2488         *
2489         *  The device MUST either present notify_off_multiplier as an even
2490         *  power of 2, or present notify_off_multiplier as 0.
2491         *
2492         * 2.1.2:
2493         *
2494         *   The device MUST initialize device status to 0 upon reset. 
2495         */
2496        memset(pci, 0, sizeof(*pci));
2497
2498        /* 4.1.2.1: Devices MUST have the PCI Vendor ID 0x1AF4 */
2499        pci->vendor_id = 0x1AF4;
2500        /* 4.1.2.1: ... PCI Device ID calculated by adding 0x1040 ... */
2501        pci->device_id = 0x1040 + type;
2502
2503        /*
2504         * PCI have specific codes for different types of devices.
2505         * Linux doesn't care, but it's a good clue for people looking
2506         * at the device.
2507         */
2508        pci->class = class;
2509        pci->subclass = subclass;
2510
2511        /*
2512         * 4.1.2.1:
2513         *
2514         *  Non-transitional devices SHOULD have a PCI Revision ID of 1 or
2515         *  higher
2516         */
2517        pci->revid = 1;
2518
2519        /*
2520         * 4.1.2.1:
2521         *
2522         *  Non-transitional devices SHOULD have a PCI Subsystem Device ID of
2523         *  0x40 or higher.
2524         */
2525        pci->subsystem_device_id = 0x40;
2526
2527        /* We use our dummy interrupt controller, and irq_line is the irq */
2528        pci->irq_line = devices.next_irq++;
2529        pci->irq_pin = 0;
2530
2531        /* Support for extended capabilities. */
2532        pci->status = (1 << 4);
2533
2534        /* Link them in. */
2535        /*
2536         * 4.1.4.3.1:
2537         *
2538         *  The device MUST present at least one common configuration
2539         *  capability.
2540         */
2541        pci->capabilities = offsetof(struct pci_config, common);
2542
2543        /* 4.1.4.3.1 ... offset MUST be 4-byte aligned. */
2544        assert(pci->capabilities % 4 == 0);
2545
2546        bar_offset = offsetof(struct virtio_pci_mmio, cfg);
2547        bar_len = sizeof(((struct virtio_pci_mmio *)0)->cfg);
2548        init_cap(&pci->common, sizeof(pci->common), VIRTIO_PCI_CAP_COMMON_CFG,
2549                 bar_offset, bar_len,
2550                 offsetof(struct pci_config, notify));
2551
2552        /*
2553         * 4.1.4.4.1:
2554         *
2555         *  The device MUST present at least one notification capability.
2556         */
2557        bar_offset += bar_len;
2558        bar_len = sizeof(((struct virtio_pci_mmio *)0)->notify);
2559
2560        /*
2561         * 4.1.4.4.1:
2562         *
2563         *  The cap.offset MUST be 2-byte aligned.
2564         */
2565        assert(pci->common.cap_next % 2 == 0);
2566
2567        /* FIXME: Use a non-zero notify_off, for per-queue notification? */
2568        /*
2569         * 4.1.4.4.1:
2570         *
2571         *  The value cap.length presented by the device MUST be at least 2 and
2572         *  MUST be large enough to support queue notification offsets for all
2573         *  supported queues in all possible configurations.
2574         */
2575        assert(bar_len >= 2);
2576
2577        init_cap(&pci->notify.cap, sizeof(pci->notify),
2578                 VIRTIO_PCI_CAP_NOTIFY_CFG,
2579                 bar_offset, bar_len,
2580                 offsetof(struct pci_config, isr));
2581
2582        bar_offset += bar_len;
2583        bar_len = sizeof(((struct virtio_pci_mmio *)0)->isr);
2584        /*
2585         * 4.1.4.5.1:
2586         *
2587         *  The device MUST present at least one VIRTIO_PCI_CAP_ISR_CFG
2588         *  capability.
2589         */
2590        init_cap(&pci->isr, sizeof(pci->isr),
2591                 VIRTIO_PCI_CAP_ISR_CFG,
2592                 bar_offset, bar_len,
2593                 offsetof(struct pci_config, cfg_access));
2594
2595        /*
2596         * 4.1.4.7.1:
2597         *
2598         * The device MUST present at least one VIRTIO_PCI_CAP_PCI_CFG
2599         * capability.
2600         */
2601        /* This doesn't have any presence in the BAR */
2602        init_cap(&pci->cfg_access.cap, sizeof(pci->cfg_access),
2603                 VIRTIO_PCI_CAP_PCI_CFG,
2604                 0, 0, 0);
2605
2606        bar_offset += bar_len + sizeof(((struct virtio_pci_mmio *)0)->padding);
2607        assert(bar_offset == sizeof(struct virtio_pci_mmio));
2608
2609        /*
2610         * This gets sewn in and length set in set_device_config().
2611         * Some devices don't have a device configuration interface, so
2612         * we never expose this if we don't call set_device_config().
2613         */
2614        init_cap(&pci->device, sizeof(pci->device), VIRTIO_PCI_CAP_DEVICE_CFG,
2615                 bar_offset, 0, 0);
2616}
2617
2618/*
2619 * This routine does all the creation and setup of a new device, but we don't
2620 * actually place the MMIO region until we know the size (if any) of the
2621 * device-specific config.  And we don't actually start the service threads
2622 * until later.
2623 *
2624 * See what I mean about userspace being boring?
2625 */
2626static struct device *new_pci_device(const char *name, u16 type,
2627                                     u8 class, u8 subclass)
2628{
2629        struct device *dev = malloc(sizeof(*dev));
2630
2631        /* Now we populate the fields one at a time. */
2632        dev->name = name;
2633        dev->vq = NULL;
2634        dev->running = false;
2635        dev->wrote_features_ok = false;
2636        dev->mmio_size = sizeof(struct virtio_pci_mmio);
2637        dev->mmio = calloc(1, dev->mmio_size);
2638        dev->features = (u64)1 << VIRTIO_F_VERSION_1;
2639        dev->features_accepted = 0;
2640
2641        if (devices.device_num + 1 >= MAX_PCI_DEVICES)
2642                errx(1, "Can only handle 31 PCI devices");
2643
2644        init_pci_config(&dev->config, type, class, subclass);
2645        assert(!devices.pci[devices.device_num+1]);
2646        devices.pci[++devices.device_num] = dev;
2647
2648        return dev;
2649}
2650
2651/*
2652 * Our first setup routine is the console.  It's a fairly simple device, but
2653 * UNIX tty handling makes it uglier than it could be.
2654 */
2655static void setup_console(void)
2656{
2657        struct device *dev;
2658        struct virtio_console_config conf;
2659
2660        /* If we can save the initial standard input settings... */
2661        if (tcgetattr(STDIN_FILENO, &orig_term) == 0) {
2662                struct termios term = orig_term;
2663                /*
2664                 * Then we turn off echo, line buffering and ^C etc: We want a
2665                 * raw input stream to the Guest.
2666                 */
2667                term.c_lflag &= ~(ISIG|ICANON|ECHO);
2668                tcsetattr(STDIN_FILENO, TCSANOW, &term);
2669        }
2670
2671        dev = new_pci_device("console", VIRTIO_ID_CONSOLE, 0x07, 0x00);
2672
2673        /* We store the console state in dev->priv, and initialize it. */
2674        dev->priv = malloc(sizeof(struct console_abort));
2675        ((struct console_abort *)dev->priv)->count = 0;
2676
2677        /*
2678         * The console needs two virtqueues: the input then the output.  When
2679         * they put something the input queue, we make sure we're listening to
2680         * stdin.  When they put something in the output queue, we write it to
2681         * stdout.
2682         */
2683        add_pci_virtqueue(dev, console_input, "input");
2684        add_pci_virtqueue(dev, console_output, "output");
2685
2686        /* We need a configuration area for the emerg_wr early writes. */
2687        add_pci_feature(dev, VIRTIO_CONSOLE_F_EMERG_WRITE);
2688        set_device_config(dev, &conf, sizeof(conf));
2689
2690        verbose("device %u: console\n", devices.device_num);
2691}
2692/*:*/
2693
2694/*M:010
2695 * Inter-guest networking is an interesting area.  Simplest is to have a
2696 * --sharenet=<name> option which opens or creates a named pipe.  This can be
2697 * used to send packets to another guest in a 1:1 manner.
2698 *
2699 * More sophisticated is to use one of the tools developed for project like UML
2700 * to do networking.
2701 *
2702 * Faster is to do virtio bonding in kernel.  Doing this 1:1 would be
2703 * completely generic ("here's my vring, attach to your vring") and would work
2704 * for any traffic.  Of course, namespace and permissions issues need to be
2705 * dealt with.  A more sophisticated "multi-channel" virtio_net.c could hide
2706 * multiple inter-guest channels behind one interface, although it would
2707 * require some manner of hotplugging new virtio channels.
2708 *
2709 * Finally, we could use a virtio network switch in the kernel, ie. vhost.
2710:*/
2711
2712static u32 str2ip(const char *ipaddr)
2713{
2714        unsigned int b[4];
2715
2716        if (sscanf(ipaddr, "%u.%u.%u.%u", &b[0], &b[1], &b[2], &b[3]) != 4)
2717                errx(1, "Failed to parse IP address '%s'", ipaddr);
2718        return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3];
2719}
2720
2721static void str2mac(const char *macaddr, unsigned char mac[6])
2722{
2723        unsigned int m[6];
2724        if (sscanf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x",
2725                   &m[0], &m[1], &m[2], &m[3], &m[4], &m[5]) != 6)
2726                errx(1, "Failed to parse mac address '%s'", macaddr);
2727        mac[0] = m[0];
2728        mac[1] = m[1];
2729        mac[2] = m[2];
2730        mac[3] = m[3];
2731        mac[4] = m[4];
2732        mac[5] = m[5];
2733}
2734
2735/*
2736 * This code is "adapted" from libbridge: it attaches the Host end of the
2737 * network device to the bridge device specified by the command line.
2738 *
2739 * This is yet another James Morris contribution (I'm an IP-level guy, so I
2740 * dislike bridging), and I just try not to break it.
2741 */
2742static void add_to_bridge(int fd, const char *if_name, const char *br_name)
2743{
2744        int ifidx;
2745        struct ifreq ifr;
2746
2747        if (!*br_name)
2748                errx(1, "must specify bridge name");
2749
2750        ifidx = if_nametoindex(if_name);
2751        if (!ifidx)
2752                errx(1, "interface %s does not exist!", if_name);
2753
2754        strncpy(ifr.ifr_name, br_name, IFNAMSIZ);
2755        ifr.ifr_name[IFNAMSIZ-1] = '\0';
2756        ifr.ifr_ifindex = ifidx;
2757        if (ioctl(fd, SIOCBRADDIF, &ifr) < 0)
2758                err(1, "can't add %s to bridge %s", if_name, br_name);
2759}
2760
2761/*
2762 * This sets up the Host end of the network device with an IP address, brings
2763 * it up so packets will flow, the copies the MAC address into the hwaddr
2764 * pointer.
2765 */
2766static void configure_device(int fd, const char *tapif, u32 ipaddr)
2767{
2768        struct ifreq ifr;
2769        struct sockaddr_in sin;
2770
2771        memset(&ifr, 0, sizeof(ifr));
2772        strcpy(ifr.ifr_name, tapif);
2773
2774        /* Don't read these incantations.  Just cut & paste them like I did! */
2775        sin.sin_family = AF_INET;
2776        sin.sin_addr.s_addr = htonl(ipaddr);
2777        memcpy(&ifr.ifr_addr, &sin, sizeof(sin));
2778        if (ioctl(fd, SIOCSIFADDR, &ifr) != 0)
2779                err(1, "Setting %s interface address", tapif);
2780        ifr.ifr_flags = IFF_UP;
2781        if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0)
2782                err(1, "Bringing interface %s up", tapif);
2783}
2784
2785static int get_tun_device(char tapif[IFNAMSIZ])
2786{
2787        struct ifreq ifr;
2788        int vnet_hdr_sz;
2789        int netfd;
2790
2791        /* Start with this zeroed.  Messy but sure. */
2792        memset(&ifr, 0, sizeof(ifr));
2793
2794        /*
2795         * We open the /dev/net/tun device and tell it we want a tap device.  A
2796         * tap device is like a tun device, only somehow different.  To tell
2797         * the truth, I completely blundered my way through this code, but it
2798         * works now!
2799         */
2800        netfd = open_or_die("/dev/net/tun", O_RDWR);
2801        ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
2802        strcpy(ifr.ifr_name, "tap%d");
2803        if (ioctl(netfd, TUNSETIFF, &ifr) != 0)
2804                err(1, "configuring /dev/net/tun");
2805
2806        if (ioctl(netfd, TUNSETOFFLOAD,
2807                  TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0)
2808                err(1, "Could not set features for tun device");
2809
2810        /*
2811         * We don't need checksums calculated for packets coming in this
2812         * device: trust us!
2813         */
2814        ioctl(netfd, TUNSETNOCSUM, 1);
2815
2816        /*
2817         * In virtio before 1.0 (aka legacy virtio), we added a 16-bit
2818         * field at the end of the network header iff
2819         * VIRTIO_NET_F_MRG_RXBUF was negotiated.  For virtio 1.0,
2820         * that became the norm, but we need to tell the tun device
2821         * about our expanded header (which is called
2822         * virtio_net_hdr_mrg_rxbuf in the legacy system).
2823         */
2824        vnet_hdr_sz = sizeof(struct virtio_net_hdr_v1);
2825        if (ioctl(netfd, TUNSETVNETHDRSZ, &vnet_hdr_sz) != 0)
2826                err(1, "Setting tun header size to %u", vnet_hdr_sz);
2827
2828        memcpy(tapif, ifr.ifr_name, IFNAMSIZ);
2829        return netfd;
2830}
2831
2832/*L:195
2833 * Our network is a Host<->Guest network.  This can either use bridging or
2834 * routing, but the principle is the same: it uses the "tun" device to inject
2835 * packets into the Host as if they came in from a normal network card.  We
2836 * just shunt packets between the Guest and the tun device.
2837 */
2838static void setup_tun_net(char *arg)
2839{
2840        struct device *dev;
2841        struct net_info *net_info = malloc(sizeof(*net_info));
2842        int ipfd;
2843        u32 ip = INADDR_ANY;
2844        bool bridging = false;
2845        char tapif[IFNAMSIZ], *p;
2846        struct virtio_net_config conf;
2847
2848        net_info->tunfd = get_tun_device(tapif);
2849
2850        /* First we create a new network device. */
2851        dev = new_pci_device("net", VIRTIO_ID_NET, 0x02, 0x00);
2852        dev->priv = net_info;
2853
2854        /* Network devices need a recv and a send queue, just like console. */
2855        add_pci_virtqueue(dev, net_input, "rx");
2856        add_pci_virtqueue(dev, net_output, "tx");
2857
2858        /*
2859         * We need a socket to perform the magic network ioctls to bring up the
2860         * tap interface, connect to the bridge etc.  Any socket will do!
2861         */
2862        ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
2863        if (ipfd < 0)
2864                err(1, "opening IP socket");
2865
2866        /* If the command line was --tunnet=bridge:<name> do bridging. */
2867        if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) {
2868                arg += strlen(BRIDGE_PFX);
2869                bridging = true;
2870        }
2871
2872        /* A mac address may follow the bridge name or IP address */
2873        p = strchr(arg, ':');
2874        if (p) {
2875                str2mac(p+1, conf.mac);
2876                add_pci_feature(dev, VIRTIO_NET_F_MAC);
2877                *p = '\0';
2878        }
2879
2880        /* arg is now either an IP address or a bridge name */
2881        if (bridging)
2882                add_to_bridge(ipfd, tapif, arg);
2883        else
2884                ip = str2ip(arg);
2885
2886        /* Set up the tun device. */
2887        configure_device(ipfd, tapif, ip);
2888
2889        /* Expect Guest to handle everything except UFO */
2890        add_pci_feature(dev, VIRTIO_NET_F_CSUM);
2891        add_pci_feature(dev, VIRTIO_NET_F_GUEST_CSUM);
2892        add_pci_feature(dev, VIRTIO_NET_F_GUEST_TSO4);
2893        add_pci_feature(dev, VIRTIO_NET_F_GUEST_TSO6);
2894        add_pci_feature(dev, VIRTIO_NET_F_GUEST_ECN);
2895        add_pci_feature(dev, VIRTIO_NET_F_HOST_TSO4);
2896        add_pci_feature(dev, VIRTIO_NET_F_HOST_TSO6);
2897        add_pci_feature(dev, VIRTIO_NET_F_HOST_ECN);
2898        /* We handle indirect ring entries */
2899        add_pci_feature(dev, VIRTIO_RING_F_INDIRECT_DESC);
2900        set_device_config(dev, &conf, sizeof(conf));
2901
2902        /* We don't need the socket any more; setup is done. */
2903        close(ipfd);
2904
2905        if (bridging)
2906                verbose("device %u: tun %s attached to bridge: %s\n",
2907                        devices.device_num, tapif, arg);
2908        else
2909                verbose("device %u: tun %s: %s\n",
2910                        devices.device_num, tapif, arg);
2911}
2912/*:*/
2913
2914/* This hangs off device->priv. */
2915struct vblk_info {
2916        /* The size of the file. */
2917        off64_t len;
2918
2919        /* The file descriptor for the file. */
2920        int fd;
2921
2922};
2923
2924/*L:210
2925 * The Disk
2926 *
2927 * The disk only has one virtqueue, so it only has one thread.  It is really
2928 * simple: the Guest asks for a block number and we read or write that position
2929 * in the file.
2930 *
2931 * Before we serviced each virtqueue in a separate thread, that was unacceptably
2932 * slow: the Guest waits until the read is finished before running anything
2933 * else, even if it could have been doing useful work.
2934 *
2935 * We could have used async I/O, except it's reputed to suck so hard that
2936 * characters actually go missing from your code when you try to use it.
2937 */
2938static void blk_request(struct virtqueue *vq)
2939{
2940        struct vblk_info *vblk = vq->dev->priv;
2941        unsigned int head, out_num, in_num, wlen;
2942        int ret, i;
2943        u8 *in;
2944        struct virtio_blk_outhdr out;
2945        struct iovec iov[vq->vring.num];
2946        off64_t off;
2947
2948        /*
2949         * Get the next request, where we normally wait.  It triggers the
2950         * interrupt to acknowledge previously serviced requests (if any).
2951         */
2952        head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
2953
2954        /* Copy the output header from the front of the iov (adjusts iov) */
2955        iov_consume(vq->dev, iov, out_num, &out, sizeof(out));
2956
2957        /* Find and trim end of iov input array, for our status byte. */
2958        in = NULL;
2959        for (i = out_num + in_num - 1; i >= out_num; i--) {
2960                if (iov[i].iov_len > 0) {
2961                        in = iov[i].iov_base + iov[i].iov_len - 1;
2962                        iov[i].iov_len--;
2963                        break;
2964                }
2965        }
2966        if (!in)
2967                bad_driver_vq(vq, "Bad virtblk cmd with no room for status");
2968
2969        /*
2970         * For historical reasons, block operations are expressed in 512 byte
2971         * "sectors".
2972         */
2973        off = out.sector * 512;
2974
2975        if (out.type & VIRTIO_BLK_T_OUT) {
2976                /*
2977                 * Write
2978                 *
2979                 * Move to the right location in the block file.  This can fail
2980                 * if they try to write past end.
2981                 */
2982                if (lseek64(vblk->fd, off, SEEK_SET) != off)
2983                        err(1, "Bad seek to sector %llu", out.sector);
2984
2985                ret = writev(vblk->fd, iov, out_num);
2986                verbose("WRITE to sector %llu: %i\n", out.sector, ret);
2987
2988                /*
2989                 * Grr... Now we know how long the descriptor they sent was, we
2990                 * make sure they didn't try to write over the end of the block
2991                 * file (possibly extending it).
2992                 */
2993                if (ret > 0 && off + ret > vblk->len) {
2994                        /* Trim it back to the correct length */
2995                        ftruncate64(vblk->fd, vblk->len);
2996                        /* Die, bad Guest, die. */
2997                        bad_driver_vq(vq, "Write past end %llu+%u", off, ret);
2998                }
2999
3000                wlen = sizeof(*in);
3001                *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
3002        } else if (out.type & VIRTIO_BLK_T_FLUSH) {
3003                /* Flush */
3004                ret = fdatasync(vblk->fd);
3005                verbose("FLUSH fdatasync: %i\n", ret);
3006                wlen = sizeof(*in);
3007                *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
3008        } else {
3009                /*
3010                 * Read
3011                 *
3012                 * Move to the right location in the block file.  This can fail
3013                 * if they try to read past end.
3014                 */
3015                if (lseek64(vblk->fd, off, SEEK_SET) != off)
3016                        err(1, "Bad seek to sector %llu", out.sector);
3017
3018                ret = readv(vblk->fd, iov + out_num, in_num);
3019                if (ret >= 0) {
3020                        wlen = sizeof(*in) + ret;
3021                        *in = VIRTIO_BLK_S_OK;
3022                } else {
3023                        wlen = sizeof(*in);
3024                        *in = VIRTIO_BLK_S_IOERR;
3025                }
3026        }
3027
3028        /* Finished that request. */
3029        add_used(vq, head, wlen);
3030}
3031
3032/*L:198 This actually sets up a virtual block device. */
3033static void setup_block_file(const char *filename)
3034{
3035        struct device *dev;
3036        struct vblk_info *vblk;
3037        struct virtio_blk_config conf;
3038
3039        /* Create the device. */
3040        dev = new_pci_device("block", VIRTIO_ID_BLOCK, 0x01, 0x80);
3041
3042        /* The device has one virtqueue, where the Guest places requests. */
3043        add_pci_virtqueue(dev, blk_request, "request");
3044
3045        /* Allocate the room for our own bookkeeping */
3046        vblk = dev->priv = malloc(sizeof(*vblk));
3047
3048        /* First we open the file and store the length. */
3049        vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE);
3050        vblk->len = lseek64(vblk->fd, 0, SEEK_END);
3051
3052        /* Tell Guest how many sectors this device has. */
3053        conf.capacity = cpu_to_le64(vblk->len / 512);
3054
3055        /*
3056         * Tell Guest not to put in too many descriptors at once: two are used
3057         * for the in and out elements.
3058         */
3059        add_pci_feature(dev, VIRTIO_BLK_F_SEG_MAX);
3060        conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2);
3061
3062        set_device_config(dev, &conf, sizeof(struct virtio_blk_config));
3063
3064        verbose("device %u: virtblock %llu sectors\n",
3065                devices.device_num, le64_to_cpu(conf.capacity));
3066}
3067
3068/*L:211
3069 * Our random number generator device reads from /dev/urandom into the Guest's
3070 * input buffers.  The usual case is that the Guest doesn't want random numbers
3071 * and so has no buffers although /dev/urandom is still readable, whereas
3072 * console is the reverse.
3073 *
3074 * The same logic applies, however.
3075 */
3076struct rng_info {
3077        int rfd;
3078};
3079
3080static void rng_input(struct virtqueue *vq)
3081{
3082        int len;
3083        unsigned int head, in_num, out_num, totlen = 0;
3084        struct rng_info *rng_info = vq->dev->priv;
3085        struct iovec iov[vq->vring.num];
3086
3087        /* First we need a buffer from the Guests's virtqueue. */
3088        head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
3089        if (out_num)
3090                bad_driver_vq(vq, "Output buffers in rng?");
3091
3092        /*
3093         * Just like the console write, we loop to cover the whole iovec.
3094         * In this case, short reads actually happen quite a bit.
3095         */
3096        while (!iov_empty(iov, in_num)) {
3097                len = readv(rng_info->rfd, iov, in_num);
3098                if (len <= 0)
3099                        err(1, "Read from /dev/urandom gave %i", len);
3100                iov_consume(vq->dev, iov, in_num, NULL, len);
3101                totlen += len;
3102        }
3103
3104        /* Tell the Guest about the new input. */
3105        add_used(vq, head, totlen);
3106}
3107
3108/*L:199
3109 * This creates a "hardware" random number device for the Guest.
3110 */
3111static void setup_rng(void)
3112{
3113        struct device *dev;
3114        struct rng_info *rng_info = malloc(sizeof(*rng_info));
3115
3116        /* Our device's private info simply contains the /dev/urandom fd. */
3117        rng_info->rfd = open_or_die("/dev/urandom", O_RDONLY);
3118
3119        /* Create the new device. */
3120        dev = new_pci_device("rng", VIRTIO_ID_RNG, 0xff, 0);
3121        dev->priv = rng_info;
3122
3123        /* The device has one virtqueue, where the Guest places inbufs. */
3124        add_pci_virtqueue(dev, rng_input, "input");
3125
3126        /* We don't have any configuration space */
3127        no_device_config(dev);
3128
3129        verbose("device %u: rng\n", devices.device_num);
3130}
3131/* That's the end of device setup. */
3132
3133/*L:230 Reboot is pretty easy: clean up and exec() the Launcher afresh. */
3134static void __attribute__((noreturn)) restart_guest(void)
3135{
3136        unsigned int i;
3137
3138        /*
3139         * Since we don't track all open fds, we simply close everything beyond
3140         * stderr.
3141         */
3142        for (i = 3; i < FD_SETSIZE; i++)
3143                close(i);
3144
3145        /* Reset all the devices (kills all threads). */
3146        cleanup_devices();
3147
3148        execv(main_args[0], main_args);
3149        err(1, "Could not exec %s", main_args[0]);
3150}
3151
3152/*L:220
3153 * Finally we reach the core of the Launcher which runs the Guest, serves
3154 * its input and output, and finally, lays it to rest.
3155 */
3156static void __attribute__((noreturn)) run_guest(void)
3157{
3158        for (;;) {
3159                struct lguest_pending notify;
3160                int readval;
3161
3162                /* We read from the /dev/lguest device to run the Guest. */
3163                readval = pread(lguest_fd, &notify, sizeof(notify), cpu_id);
3164                if (readval == sizeof(notify)) {
3165                        if (notify.trap == 13) {
3166                                verbose("Emulating instruction at %#x\n",
3167                                        getreg(eip));
3168                                emulate_insn(notify.insn);
3169                        } else if (notify.trap == 14) {
3170                                verbose("Emulating MMIO at %#x\n",
3171                                        getreg(eip));
3172                                emulate_mmio(notify.addr, notify.insn);
3173                        } else
3174                                errx(1, "Unknown trap %i addr %#08x\n",
3175                                     notify.trap, notify.addr);
3176                /* ENOENT means the Guest died.  Reading tells us why. */
3177                } else if (errno == ENOENT) {
3178                        char reason[1024] = { 0 };
3179                        pread(lguest_fd, reason, sizeof(reason)-1, cpu_id);
3180                        errx(1, "%s", reason);
3181                /* ERESTART means that we need to reboot the guest */
3182                } else if (errno == ERESTART) {
3183                        restart_guest();
3184                /* Anything else means a bug or incompatible change. */
3185                } else
3186                        err(1, "Running guest failed");
3187        }
3188}
3189/*L:240
3190 * This is the end of the Launcher.  The good news: we are over halfway
3191 * through!  The bad news: the most fiendish part of the code still lies ahead
3192 * of us.
3193 *
3194 * Are you ready?  Take a deep breath and join me in the core of the Host, in
3195 * "make Host".
3196:*/
3197
3198static struct option opts[] = {
3199        { "verbose", 0, NULL, 'v' },
3200        { "tunnet", 1, NULL, 't' },
3201        { "block", 1, NULL, 'b' },
3202        { "rng", 0, NULL, 'r' },
3203        { "initrd", 1, NULL, 'i' },
3204        { "username", 1, NULL, 'u' },
3205        { "chroot", 1, NULL, 'c' },
3206        { NULL },
3207};
3208static void usage(void)
3209{
3210        errx(1, "Usage: lguest [--verbose] "
3211             "[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n"
3212             "|--block=<filename>|--initrd=<filename>]...\n"
3213             "<mem-in-mb> vmlinux [args...]");
3214}
3215
3216/*L:105 The main routine is where the real work begins: */
3217int main(int argc, char *argv[])
3218{
3219        /* Memory, code startpoint and size of the (optional) initrd. */
3220        unsigned long mem = 0, start, initrd_size = 0;
3221        /* Two temporaries. */
3222        int i, c;
3223        /* The boot information for the Guest. */
3224        struct boot_params *boot;
3225        /* If they specify an initrd file to load. */
3226        const char *initrd_name = NULL;
3227
3228        /* Password structure for initgroups/setres[gu]id */
3229        struct passwd *user_details = NULL;
3230
3231        /* Directory to chroot to */
3232        char *chroot_path = NULL;
3233
3234        /* Save the args: we "reboot" by execing ourselves again. */
3235        main_args = argv;
3236
3237        /*
3238         * First we initialize the device list.  We remember next interrupt
3239         * number to use for devices (1: remember that 0 is used by the timer).
3240         */
3241        devices.next_irq = 1;
3242
3243        /* We're CPU 0.  In fact, that's the only CPU possible right now. */
3244        cpu_id = 0;
3245
3246        /*
3247         * We need to know how much memory so we can set up the device
3248         * descriptor and memory pages for the devices as we parse the command
3249         * line.  So we quickly look through the arguments to find the amount
3250         * of memory now.
3251         */
3252        for (i = 1; i < argc; i++) {
3253                if (argv[i][0] != '-') {
3254                        mem = atoi(argv[i]) * 1024 * 1024;
3255                        /*
3256                         * We start by mapping anonymous pages over all of
3257                         * guest-physical memory range.  This fills it with 0,
3258                         * and ensures that the Guest won't be killed when it
3259                         * tries to access it.
3260                         */
3261                        guest_base = map_zeroed_pages(mem / getpagesize()
3262                                                      + DEVICE_PAGES);
3263                        guest_limit = mem;
3264                        guest_max = guest_mmio = mem + DEVICE_PAGES*getpagesize();
3265                        break;
3266                }
3267        }
3268
3269        /* We always have a console device, and it's always device 1. */
3270        setup_console();
3271
3272        /* The options are fairly straight-forward */
3273        while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) {
3274                switch (c) {
3275                case 'v':
3276                        verbose = true;
3277                        break;
3278                case 't':
3279                        setup_tun_net(optarg);
3280                        break;
3281                case 'b':
3282                        setup_block_file(optarg);
3283                        break;
3284                case 'r':
3285                        setup_rng();
3286                        break;
3287                case 'i':
3288                        initrd_name = optarg;
3289                        break;
3290                case 'u':
3291                        user_details = getpwnam(optarg);
3292                        if (!user_details)
3293                                err(1, "getpwnam failed, incorrect username?");
3294                        break;
3295                case 'c':
3296                        chroot_path = optarg;
3297                        break;
3298                default:
3299                        warnx("Unknown argument %s", argv[optind]);
3300                        usage();
3301                }
3302        }
3303        /*
3304         * After the other arguments we expect memory and kernel image name,
3305         * followed by command line arguments for the kernel.
3306         */
3307        if (optind + 2 > argc)
3308                usage();
3309
3310        verbose("Guest base is at %p\n", guest_base);
3311
3312        /* Initialize the (fake) PCI host bridge device. */
3313        init_pci_host_bridge();
3314
3315        /* Now we load the kernel */
3316        start = load_kernel(open_or_die(argv[optind+1], O_RDONLY));
3317
3318        /* Boot information is stashed at physical address 0 */
3319        boot = from_guest_phys(0);
3320
3321        /* Map the initrd image if requested (at top of physical memory) */
3322        if (initrd_name) {
3323                initrd_size = load_initrd(initrd_name, mem);
3324                /*
3325                 * These are the location in the Linux boot header where the
3326                 * start and size of the initrd are expected to be found.
3327                 */
3328                boot->hdr.ramdisk_image = mem - initrd_size;
3329                boot->hdr.ramdisk_size = initrd_size;
3330                /* The bootloader type 0xFF means "unknown"; that's OK. */
3331                boot->hdr.type_of_loader = 0xFF;
3332        }
3333
3334        /*
3335         * The Linux boot header contains an "E820" memory map: ours is a
3336         * simple, single region.
3337         */
3338        boot->e820_entries = 1;
3339        boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM });
3340        /*
3341         * The boot header contains a command line pointer: we put the command
3342         * line after the boot header.
3343         */
3344        boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1);
3345        /* We use a simple helper to copy the arguments separated by spaces. */
3346        concat((char *)(boot + 1), argv+optind+2);
3347
3348        /* Set kernel alignment to 16M (CONFIG_PHYSICAL_ALIGN) */
3349        boot->hdr.kernel_alignment = 0x1000000;
3350
3351        /* Boot protocol version: 2.07 supports the fields for lguest. */
3352        boot->hdr.version = 0x207;
3353
3354        /* The hardware_subarch value of "1" tells the Guest it's an lguest. */
3355        boot->hdr.hardware_subarch = 1;
3356
3357        /* Tell the entry path not to try to reload segment registers. */
3358        boot->hdr.loadflags |= KEEP_SEGMENTS;
3359
3360        /* We tell the kernel to initialize the Guest. */
3361        tell_kernel(start);
3362
3363        /* Ensure that we terminate if a device-servicing child dies. */
3364        signal(SIGCHLD, kill_launcher);
3365
3366        /* If we exit via err(), this kills all the threads, restores tty. */
3367        atexit(cleanup_devices);
3368
3369        /* If requested, chroot to a directory */
3370        if (chroot_path) {
3371                if (chroot(chroot_path) != 0)
3372                        err(1, "chroot(\"%s\") failed", chroot_path);
3373
3374                if (chdir("/") != 0)
3375                        err(1, "chdir(\"/\") failed");
3376
3377                verbose("chroot done\n");
3378        }
3379
3380        /* If requested, drop privileges */
3381        if (user_details) {
3382                uid_t u;
3383                gid_t g;
3384
3385                u = user_details->pw_uid;
3386                g = user_details->pw_gid;
3387
3388                if (initgroups(user_details->pw_name, g) != 0)
3389                        err(1, "initgroups failed");
3390
3391                if (setresgid(g, g, g) != 0)
3392                        err(1, "setresgid failed");
3393
3394                if (setresuid(u, u, u) != 0)
3395                        err(1, "setresuid failed");
3396
3397                verbose("Dropping privileges completed\n");
3398        }
3399
3400        /* Finally, run the Guest.  This doesn't return. */
3401        run_guest();
3402}
3403/*:*/
3404
3405/*M:999
3406 * Mastery is done: you now know everything I do.
3407 *
3408 * But surely you have seen code, features and bugs in your wanderings which
3409 * you now yearn to attack?  That is the real game, and I look forward to you
3410 * patching and forking lguest into the Your-Name-Here-visor.
3411 *
3412 * Farewell, and good coding!
3413 * Rusty Russell.
3414 */
3415