/*
 * Machine specific setup for xen
 *
 * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/pm.h>
#include <linux/memblock.h>

#include <asm/elf.h>
#include <asm/vdso.h>
#include <asm/e820.h>
#include <asm/setup.h>
#include <asm/acpi.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>

#include <xen/xen.h>
#include <xen/page.h>
#include <xen/interface/callback.h>
#include <xen/interface/memory.h>
#include <xen/interface/physdev.h>
#include <xen/features.h>

#include "xen-ops.h"
#include "vdso.h"

/* These are code, but not functions.  Defined in entry.S */
extern const char xen_hypervisor_callback[];
extern const char xen_failsafe_callback[];
extern void xen_sysenter_target(void);
extern void xen_syscall_target(void);
extern void xen_syscall32_target(void);

/* Amount of extra memory space we add to the e820 ranges */
phys_addr_t xen_extra_mem_start, xen_extra_mem_size;

/* 
 * The maximum amount of extra memory compared to the base size.  The
 * main scaling factor is the size of struct page.  At extreme ratios
 * of base:extra, all the base memory can be filled with page
 * structures for the extra memory, leaving no space for anything
 * else.
 * 
 * 10x seems like a reasonable balance between scaling flexibility and
 * leaving a practically usable system.
 */
#define EXTRA_MEM_RATIO         (10)

static __init void xen_add_extra_mem(unsigned long pages)
{
        u64 size = (u64)pages * PAGE_SIZE;
        u64 extra_start = xen_extra_mem_start + xen_extra_mem_size;

        if (!pages)
                return;

        e820_add_region(extra_start, size, E820_RAM);
        sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);

        memblock_x86_reserve_range(extra_start, extra_start + size, "XEN EXTRA");

        xen_extra_mem_size += size;

        xen_max_p2m_pfn = PFN_DOWN(extra_start + size);
}

static unsigned long __init xen_release_chunk(phys_addr_t start_addr,
                                              phys_addr_t end_addr)
{
        struct xen_memory_reservation reservation = {
                .address_bits = 0,
                .extent_order = 0,
                .domid        = DOMID_SELF
        };
        unsigned long start, end;
        unsigned long len = 0;
        unsigned long pfn;
        int ret;

        start = PFN_UP(start_addr);
        end = PFN_DOWN(end_addr);

        if (end <= start)
                return 0;

        printk(KERN_INFO "xen_release_chunk: looking at area pfn %lx-%lx: ",
               start, end);
        for(pfn = start; pfn < end; pfn++) {
                unsigned long mfn = pfn_to_mfn(pfn);

                /* Make sure pfn exists to start with */
                if (mfn == INVALID_P2M_ENTRY || mfn_to_pfn(mfn) != pfn)
                        continue;

                set_xen_guest_handle(reservation.extent_start, &mfn);
                reservation.nr_extents = 1;

                ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
                                           &reservation);
                WARN(ret != 1, "Failed to release memory %lx-%lx err=%d\n",
                     start, end, ret);
                if (ret == 1) {
                        set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
                        len++;
                }
        }
        printk(KERN_CONT "%ld pages freed\n", len);

        return len;
}

static unsigned long __init xen_return_unused_memory(unsigned long max_pfn,
                                                     const struct e820map *e820)
{
        phys_addr_t max_addr = PFN_PHYS(max_pfn);
        phys_addr_t last_end = ISA_END_ADDRESS;
        unsigned long released = 0;
        int i;

        /* Free any unused memory above the low 1Mbyte. */
        for (i = 0; i < e820->nr_map && last_end < max_addr; i++) {
                phys_addr_t end = e820->map[i].addr;
                end = min(max_addr, end);

                if (last_end < end)
                        released += xen_release_chunk(last_end, end);
                last_end = max(last_end, e820->map[i].addr + e820->map[i].size);
        }

        if (last_end < max_addr)
                released += xen_release_chunk(last_end, max_addr);

        printk(KERN_INFO "released %ld pages of unused memory\n", released);
        return released;
}

/**
 * machine_specific_memory_setup - Hook for machine specific memory setup.
 **/
char * __init xen_memory_setup(void)
{
        static struct e820entry map[E820MAX] __initdata;

        unsigned long max_pfn = xen_start_info->nr_pages;
        unsigned long long mem_end;
        int rc;
        struct xen_memory_map memmap;
        unsigned long extra_pages = 0;
        unsigned long extra_limit;
        int i;
        int op;

        max_pfn = min(MAX_DOMAIN_PAGES, max_pfn);
        mem_end = PFN_PHYS(max_pfn);

        memmap.nr_entries = E820MAX;
        set_xen_guest_handle(memmap.buffer, map);

        op = xen_initial_domain() ?
                XENMEM_machine_memory_map :
                XENMEM_memory_map;
        rc = HYPERVISOR_memory_op(op, &memmap);
        if (rc == -ENOSYS) {
                BUG_ON(xen_initial_domain());
                memmap.nr_entries = 1;
                map[0].addr = 0ULL;
                map[0].size = mem_end;
                /* 8MB slack (to balance backend allocations). */
                map[0].size += 8ULL << 20;
                map[0].type = E820_RAM;
                rc = 0;
        }
        BUG_ON(rc);

        e820.nr_map = 0;
        xen_extra_mem_start = mem_end;
        for (i = 0; i < memmap.nr_entries; i++) {
                unsigned long long end;

                /* Guard against non-page aligned E820 entries. */
                if (map[i].type == E820_RAM)
                        map[i].size -= (map[i].size + map[i].addr) % PAGE_SIZE;

                end = map[i].addr + map[i].size;
                if (map[i].type == E820_RAM && end > mem_end) {
                        /* RAM off the end - may be partially included */
                        u64 delta = min(map[i].size, end - mem_end);

                        map[i].size -= delta;
                        end -= delta;

                        extra_pages += PFN_DOWN(delta);
                }

                if (map[i].size > 0 && end > xen_extra_mem_start)
                        xen_extra_mem_start = end;

                /* Add region if any remains */
                if (map[i].size > 0)
                        e820_add_region(map[i].addr, map[i].size, map[i].type);
        }

        /*
         * In domU, the ISA region is normal, usable memory, but we
         * reserve ISA memory anyway because too many things poke
         * about in there.
         *
         * In Dom0, the host E820 information can leave gaps in the
         * ISA range, which would cause us to release those pages.  To
         * avoid this, we unconditionally reserve them here.
         */
        e820_add_region(ISA_START_ADDRESS, ISA_END_ADDRESS - ISA_START_ADDRESS,
                        E820_RESERVED);

        /*
         * Reserve Xen bits:
         *  - mfn_list
         *  - xen_start_info
         * See comment above "struct start_info" in <xen/interface/xen.h>
         */
        memblock_x86_reserve_range(__pa(xen_start_info->mfn_list),
                      __pa(xen_start_info->pt_base),
                        "XEN START INFO");

        sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);

        extra_pages += xen_return_unused_memory(xen_start_info->nr_pages, &e820);

        /*
         * Clamp the amount of extra memory to a EXTRA_MEM_RATIO
         * factor the base size.  On non-highmem systems, the base
         * size is the full initial memory allocation; on highmem it
         * is limited to the max size of lowmem, so that it doesn't
         * get completely filled.
         *
         * In principle there could be a problem in lowmem systems if
         * the initial memory is also very large with respect to
         * lowmem, but we won't try to deal with that here.
         */
        extra_limit = min(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)),
                          max_pfn + extra_pages);

        if (extra_limit >= max_pfn)
                extra_pages = extra_limit - max_pfn;
        else
                extra_pages = 0;

        xen_add_extra_mem(extra_pages);

        return "Xen";
}

/*
 * Set the bit indicating "nosegneg" library variants should be used.
 * We only need to bother in pure 32-bit mode; compat 32-bit processes
 * can have un-truncated segments, so wrapping around is allowed.
 */
static void __init fiddle_vdso(void)
{
#ifdef CONFIG_X86_32
        u32 *mask;
        mask = VDSO32_SYMBOL(&vdso32_int80_start, NOTE_MASK);
        *mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;
        mask = VDSO32_SYMBOL(&vdso32_sysenter_start, NOTE_MASK);
        *mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;
#endif
}

static __cpuinit int register_callback(unsigned type, const void *func)
{
        struct callback_register callback = {
                .type = type,
                .address = XEN_CALLBACK(__KERNEL_CS, func),
                .flags = CALLBACKF_mask_events,
        };

        return HYPERVISOR_callback_op(CALLBACKOP_register, &callback);
}

void __cpuinit xen_enable_sysenter(void)
{
        int ret;
        unsigned sysenter_feature;

#ifdef CONFIG_X86_32
        sysenter_feature = X86_FEATURE_SEP;
#else
        sysenter_feature = X86_FEATURE_SYSENTER32;
#endif

        if (!boot_cpu_has(sysenter_feature))
                return;

        ret = register_callback(CALLBACKTYPE_sysenter, xen_sysenter_target);
        if(ret != 0)
                setup_clear_cpu_cap(sysenter_feature);
}

void __cpuinit xen_enable_syscall(void)
{
#ifdef CONFIG_X86_64
        int ret;

        ret = register_callback(CALLBACKTYPE_syscall, xen_syscall_target);
        if (ret != 0) {
                printk(KERN_ERR "Failed to set syscall callback: %d\n", ret);
                /* Pretty fatal; 64-bit userspace has no other
                   mechanism for syscalls. */
        }

        if (boot_cpu_has(X86_FEATURE_SYSCALL32)) {
                ret = register_callback(CALLBACKTYPE_syscall32,
                                        xen_syscall32_target);
                if (ret != 0)
                        setup_clear_cpu_cap(X86_FEATURE_SYSCALL32);
        }
#endif /* CONFIG_X86_64 */
}

void __init xen_arch_setup(void)
{
        xen_panic_handler_init();

        HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_4gb_segments);
        HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_writable_pagetables);

        if (!xen_feature(XENFEAT_auto_translated_physmap))
                HYPERVISOR_vm_assist(VMASST_CMD_enable,
                                     VMASST_TYPE_pae_extended_cr3);

        if (register_callback(CALLBACKTYPE_event, xen_hypervisor_callback) ||
            register_callback(CALLBACKTYPE_failsafe, xen_failsafe_callback))
                BUG();

        xen_enable_sysenter();
        xen_enable_syscall();

#ifdef CONFIG_ACPI
        if (!(xen_start_info->flags & SIF_INITDOMAIN)) {
                printk(KERN_INFO "ACPI in unprivileged domain disabled\n");
                disable_acpi();
        }
#endif

        memcpy(boot_command_line, xen_start_info->cmd_line,
               MAX_GUEST_CMDLINE > COMMAND_LINE_SIZE ?
               COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);

        /* Set up idle, making sure it calls safe_halt() pvop */
#ifdef CONFIG_X86_32
        boot_cpu_data.hlt_works_ok = 1;
#endif
        pm_idle = default_idle;
        boot_option_idle_override = IDLE_HALT;

        fiddle_vdso();
}