// SPDX-License-Identifier: GPL-2.0-or-later
/*  Paravirtualization interfaces
    Copyright (C) 2006 Rusty Russell IBM Corporation


    2007 - x86_64 support added by Glauber de Oliveira Costa, Red Hat Inc
*/

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/efi.h>
#include <linux/bcd.h>
#include <linux/highmem.h>
#include <linux/kprobes.h>

#include <asm/bug.h>
#include <asm/paravirt.h>
#include <asm/debugreg.h>
#include <asm/desc.h>
#include <asm/setup.h>
#include <asm/pgtable.h>
#include <asm/time.h>
#include <asm/pgalloc.h>
#include <asm/irq.h>
#include <asm/delay.h>
#include <asm/fixmap.h>
#include <asm/apic.h>
#include <asm/tlbflush.h>
#include <asm/timer.h>
#include <asm/special_insns.h>
#include <asm/tlb.h>

/*
 * nop stub, which must not clobber anything *including the stack* to
 * avoid confusing the entry prologues.
 */
extern void _paravirt_nop(void);
asm (".pushsection .entry.text, \"ax\"\n"
     ".global _paravirt_nop\n"
     "_paravirt_nop:\n\t"
     "ret\n\t"
     ".size _paravirt_nop, . - _paravirt_nop\n\t"
     ".type _paravirt_nop, @function\n\t"
     ".popsection");

void __init default_banner(void)
{
        printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
               pv_info.name);
}

/* Undefined instruction for dealing with missing ops pointers. */
static const unsigned char ud2a[] = { 0x0f, 0x0b };

struct branch {
        unsigned char opcode;
        u32 delta;
} __attribute__((packed));

static unsigned paravirt_patch_call(void *insn_buff, const void *target,
                                    unsigned long addr, unsigned len)
{
        const int call_len = 5;
        struct branch *b = insn_buff;
        unsigned long delta = (unsigned long)target - (addr+call_len);

        if (len < call_len) {
                pr_warn("paravirt: Failed to patch indirect CALL at %ps\n", (void *)addr);
                /* Kernel might not be viable if patching fails, bail out: */
                BUG_ON(1);
        }

        b->opcode = 0xe8; /* call */
        b->delta = delta;
        BUILD_BUG_ON(sizeof(*b) != call_len);

        return call_len;
}

#ifdef CONFIG_PARAVIRT_XXL
/* identity function, which can be inlined */
u64 notrace _paravirt_ident_64(u64 x)
{
        return x;
}

static unsigned paravirt_patch_jmp(void *insn_buff, const void *target,
                                   unsigned long addr, unsigned len)
{
        struct branch *b = insn_buff;
        unsigned long delta = (unsigned long)target - (addr+5);

        if (len < 5) {
#ifdef CONFIG_RETPOLINE
                WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr);
#endif
                return len;     /* call too long for patch site */
        }

        b->opcode = 0xe9;       /* jmp */
        b->delta = delta;

        return 5;
}
#endif

DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);

void __init native_pv_lock_init(void)
{
        if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
                static_branch_disable(&virt_spin_lock_key);
}

unsigned paravirt_patch_default(u8 type, void *insn_buff,
                                unsigned long addr, unsigned len)
{
        /*
         * Neat trick to map patch type back to the call within the
         * corresponding structure.
         */
        void *opfunc = *((void **)&pv_ops + type);
        unsigned ret;

        if (opfunc == NULL)
                /* If there's no function, patch it with a ud2a (BUG) */
                ret = paravirt_patch_insns(insn_buff, len, ud2a, ud2a+sizeof(ud2a));
        else if (opfunc == _paravirt_nop)
                ret = 0;

#ifdef CONFIG_PARAVIRT_XXL
        /* identity functions just return their single argument */
        else if (opfunc == _paravirt_ident_64)
                ret = paravirt_patch_ident_64(insn_buff, len);

        else if (type == PARAVIRT_PATCH(cpu.iret) ||
                 type == PARAVIRT_PATCH(cpu.usergs_sysret64))
                /* If operation requires a jmp, then jmp */
                ret = paravirt_patch_jmp(insn_buff, opfunc, addr, len);
#endif
        else
                /* Otherwise call the function. */
                ret = paravirt_patch_call(insn_buff, opfunc, addr, len);

        return ret;
}

unsigned paravirt_patch_insns(void *insn_buff, unsigned len,
                              const char *start, const char *end)
{
        unsigned insn_len = end - start;

        /* Alternative instruction is too large for the patch site and we cannot continue: */
        BUG_ON(insn_len > len || start == NULL);

        memcpy(insn_buff, start, insn_len);

        return insn_len;
}

static void native_flush_tlb(void)
{
        __native_flush_tlb();
}

/*
 * Global pages have to be flushed a bit differently. Not a real
 * performance problem because this does not happen often.
 */
static void native_flush_tlb_global(void)
{
        __native_flush_tlb_global();
}

static void native_flush_tlb_one_user(unsigned long addr)
{
        __native_flush_tlb_one_user(addr);
}

struct static_key paravirt_steal_enabled;
struct static_key paravirt_steal_rq_enabled;

static u64 native_steal_clock(int cpu)
{
        return 0;
}

/* These are in entry.S */
extern void native_iret(void);
extern void native_usergs_sysret64(void);

static struct resource reserve_ioports = {
        .start = 0,
        .end = IO_SPACE_LIMIT,
        .name = "paravirt-ioport",
        .flags = IORESOURCE_IO | IORESOURCE_BUSY,
};

/*
 * Reserve the whole legacy IO space to prevent any legacy drivers
 * from wasting time probing for their hardware.  This is a fairly
 * brute-force approach to disabling all non-virtual drivers.
 *
 * Note that this must be called very early to have any effect.
 */
int paravirt_disable_iospace(void)
{
        return request_resource(&ioport_resource, &reserve_ioports);
}

static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;

static inline void enter_lazy(enum paravirt_lazy_mode mode)
{
        BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);

        this_cpu_write(paravirt_lazy_mode, mode);
}

static void leave_lazy(enum paravirt_lazy_mode mode)
{
        BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);

        this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
}

void paravirt_enter_lazy_mmu(void)
{
        enter_lazy(PARAVIRT_LAZY_MMU);
}

void paravirt_leave_lazy_mmu(void)
{
        leave_lazy(PARAVIRT_LAZY_MMU);
}

void paravirt_flush_lazy_mmu(void)
{
        preempt_disable();

        if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
                arch_leave_lazy_mmu_mode();
                arch_enter_lazy_mmu_mode();
        }

        preempt_enable();
}

#ifdef CONFIG_PARAVIRT_XXL
void paravirt_start_context_switch(struct task_struct *prev)
{
        BUG_ON(preemptible());

        if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
                arch_leave_lazy_mmu_mode();
                set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
        }
        enter_lazy(PARAVIRT_LAZY_CPU);
}

void paravirt_end_context_switch(struct task_struct *next)
{
        BUG_ON(preemptible());

        leave_lazy(PARAVIRT_LAZY_CPU);

        if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
                arch_enter_lazy_mmu_mode();
}
#endif

enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
{
        if (in_interrupt())
                return PARAVIRT_LAZY_NONE;

        return this_cpu_read(paravirt_lazy_mode);
}

struct pv_info pv_info = {
        .name = "bare hardware",
#ifdef CONFIG_PARAVIRT_XXL
        .kernel_rpl = 0,
        .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */

#ifdef CONFIG_X86_64
        .extra_user_64bit_cs = __USER_CS,
#endif
#endif
};

/* 64-bit pagetable entries */
#define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)

struct paravirt_patch_template pv_ops = {
        /* Init ops. */
        .init.patch             = native_patch,

        /* Time ops. */
        .time.sched_clock       = native_sched_clock,
        .time.steal_clock       = native_steal_clock,

        /* Cpu ops. */
        .cpu.io_delay           = native_io_delay,

#ifdef CONFIG_PARAVIRT_XXL
        .cpu.cpuid              = native_cpuid,
        .cpu.get_debugreg       = native_get_debugreg,
        .cpu.set_debugreg       = native_set_debugreg,
        .cpu.read_cr0           = native_read_cr0,
        .cpu.write_cr0          = native_write_cr0,
        .cpu.write_cr4          = native_write_cr4,
        .cpu.wbinvd             = native_wbinvd,
        .cpu.read_msr           = native_read_msr,
        .cpu.write_msr          = native_write_msr,
        .cpu.read_msr_safe      = native_read_msr_safe,
        .cpu.write_msr_safe     = native_write_msr_safe,
        .cpu.read_pmc           = native_read_pmc,
        .cpu.load_tr_desc       = native_load_tr_desc,
        .cpu.set_ldt            = native_set_ldt,
        .cpu.load_gdt           = native_load_gdt,
        .cpu.load_idt           = native_load_idt,
        .cpu.store_tr           = native_store_tr,
        .cpu.load_tls           = native_load_tls,
#ifdef CONFIG_X86_64
        .cpu.load_gs_index      = native_load_gs_index,
#endif
        .cpu.write_ldt_entry    = native_write_ldt_entry,
        .cpu.write_gdt_entry    = native_write_gdt_entry,
        .cpu.write_idt_entry    = native_write_idt_entry,

        .cpu.alloc_ldt          = paravirt_nop,
        .cpu.free_ldt           = paravirt_nop,

        .cpu.load_sp0           = native_load_sp0,

#ifdef CONFIG_X86_64
        .cpu.usergs_sysret64    = native_usergs_sysret64,
#endif
        .cpu.iret               = native_iret,
        .cpu.swapgs             = native_swapgs,

        .cpu.set_iopl_mask      = native_set_iopl_mask,

        .cpu.start_context_switch       = paravirt_nop,
        .cpu.end_context_switch         = paravirt_nop,

        /* Irq ops. */
        .irq.save_fl            = __PV_IS_CALLEE_SAVE(native_save_fl),
        .irq.restore_fl         = __PV_IS_CALLEE_SAVE(native_restore_fl),
        .irq.irq_disable        = __PV_IS_CALLEE_SAVE(native_irq_disable),
        .irq.irq_enable         = __PV_IS_CALLEE_SAVE(native_irq_enable),
        .irq.safe_halt          = native_safe_halt,
        .irq.halt               = native_halt,
#endif /* CONFIG_PARAVIRT_XXL */

        /* Mmu ops. */
        .mmu.flush_tlb_user     = native_flush_tlb,
        .mmu.flush_tlb_kernel   = native_flush_tlb_global,
        .mmu.flush_tlb_one_user = native_flush_tlb_one_user,
        .mmu.flush_tlb_others   = native_flush_tlb_others,
        .mmu.tlb_remove_table   =
                        (void (*)(struct mmu_gather *, void *))tlb_remove_page,

        .mmu.exit_mmap          = paravirt_nop,

#ifdef CONFIG_PARAVIRT_XXL
        .mmu.read_cr2           = __PV_IS_CALLEE_SAVE(native_read_cr2),
        .mmu.write_cr2          = native_write_cr2,
        .mmu.read_cr3           = __native_read_cr3,
        .mmu.write_cr3          = native_write_cr3,

        .mmu.pgd_alloc          = __paravirt_pgd_alloc,
        .mmu.pgd_free           = paravirt_nop,

        .mmu.alloc_pte          = paravirt_nop,
        .mmu.alloc_pmd          = paravirt_nop,
        .mmu.alloc_pud          = paravirt_nop,
        .mmu.alloc_p4d          = paravirt_nop,
        .mmu.release_pte        = paravirt_nop,
        .mmu.release_pmd        = paravirt_nop,
        .mmu.release_pud        = paravirt_nop,
        .mmu.release_p4d        = paravirt_nop,

        .mmu.set_pte            = native_set_pte,
        .mmu.set_pte_at         = native_set_pte_at,
        .mmu.set_pmd            = native_set_pmd,

        .mmu.ptep_modify_prot_start     = __ptep_modify_prot_start,
        .mmu.ptep_modify_prot_commit    = __ptep_modify_prot_commit,

#if CONFIG_PGTABLE_LEVELS >= 3
#ifdef CONFIG_X86_PAE
        .mmu.set_pte_atomic     = native_set_pte_atomic,
        .mmu.pte_clear          = native_pte_clear,
        .mmu.pmd_clear          = native_pmd_clear,
#endif
        .mmu.set_pud            = native_set_pud,

        .mmu.pmd_val            = PTE_IDENT,
        .mmu.make_pmd           = PTE_IDENT,

#if CONFIG_PGTABLE_LEVELS >= 4
        .mmu.pud_val            = PTE_IDENT,
        .mmu.make_pud           = PTE_IDENT,

        .mmu.set_p4d            = native_set_p4d,

#if CONFIG_PGTABLE_LEVELS >= 5
        .mmu.p4d_val            = PTE_IDENT,
        .mmu.make_p4d           = PTE_IDENT,

        .mmu.set_pgd            = native_set_pgd,
#endif /* CONFIG_PGTABLE_LEVELS >= 5 */
#endif /* CONFIG_PGTABLE_LEVELS >= 4 */
#endif /* CONFIG_PGTABLE_LEVELS >= 3 */

        .mmu.pte_val            = PTE_IDENT,
        .mmu.pgd_val            = PTE_IDENT,

        .mmu.make_pte           = PTE_IDENT,
        .mmu.make_pgd           = PTE_IDENT,

        .mmu.dup_mmap           = paravirt_nop,
        .mmu.activate_mm        = paravirt_nop,

        .mmu.lazy_mode = {
                .enter          = paravirt_nop,
                .leave          = paravirt_nop,
                .flush          = paravirt_nop,
        },

        .mmu.set_fixmap         = native_set_fixmap,
#endif /* CONFIG_PARAVIRT_XXL */

#if defined(CONFIG_PARAVIRT_SPINLOCKS)
        /* Lock ops. */
#ifdef CONFIG_SMP
        .lock.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath,
        .lock.queued_spin_unlock        =
                                PV_CALLEE_SAVE(__native_queued_spin_unlock),
        .lock.wait                      = paravirt_nop,
        .lock.kick                      = paravirt_nop,
        .lock.vcpu_is_preempted         =
                                PV_CALLEE_SAVE(__native_vcpu_is_preempted),
#endif /* SMP */
#endif
};

#ifdef CONFIG_PARAVIRT_XXL
/* At this point, native_get/set_debugreg has real function entries */
NOKPROBE_SYMBOL(native_get_debugreg);
NOKPROBE_SYMBOL(native_set_debugreg);
NOKPROBE_SYMBOL(native_load_idt);
#endif

EXPORT_SYMBOL(pv_ops);
EXPORT_SYMBOL_GPL(pv_info);