kvm_emulate.h

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/* SPDX-License-Identifier: GPL-2.0 */
/******************************************************************************
 * x86_emulate.h
 *
 * Generic x86 (32-bit and 64-bit) instruction decoder and emulator.
 *
 * Copyright (c) 2005 Keir Fraser
 *
 * From: xen-unstable 10676:af9809f51f81a3c43f276f00c81a52ef558afda4
 */
 
#ifndef _ASM_X86_KVM_X86_EMULATE_H
#define _ASM_X86_KVM_X86_EMULATE_H
 
#include <asm/desc_defs.h>
#include "fpu.h"
 
struct x86_emulate_ctxt;
enum x86_intercept;
enum x86_intercept_stage;
 
struct x86_exception {
    u8 vector;
    bool error_code_valid;
    u16 error_code;
    bool nested_page_fault;
    u64 address; /* cr2 or nested page fault gpa */
    u8 async_page_fault;
};
 
/*
 * This struct is used to carry enough information from the instruction
 * decoder to main KVM so that a decision can be made whether the
 * instruction needs to be intercepted or not.
 */
struct x86_instruction_info {
    u8  intercept;          /* which intercept                      */
    u8  rep_prefix;         /* rep prefix?                          */
    u8  modrm_mod;      /* mod part of modrm            */
    u8  modrm_reg;          /* index of register used               */
    u8  modrm_rm;       /* rm part of modrm         */
    u64 src_val;            /* value of source operand              */
    u64 dst_val;            /* value of destination operand         */
    u8  src_bytes;          /* size of source operand               */
    u8  dst_bytes;          /* size of destination operand          */
    u8  ad_bytes;           /* size of src/dst address              */
    u64 next_rip;           /* rip following the instruction        */
};
 
/*
 * x86_emulate_ops:
 *
 * These operations represent the instruction emulator's interface to memory.
 * There are two categories of operation: those that act on ordinary memory
 * regions (*_std), and those that act on memory regions known to require
 * special treatment or emulation (*_emulated).
 *
 * The emulator assumes that an instruction accesses only one 'emulated memory'
 * location, that this location is the given linear faulting address (cr2), and
 * that this is one of the instruction's data operands. Instruction fetches and
 * stack operations are assumed never to access emulated memory. The emulator
 * automatically deduces which operand of a string-move operation is accessing
 * emulated memory, and assumes that the other operand accesses normal memory.
 *
 * NOTES:
 *  1. The emulator isn't very smart about emulated vs. standard memory.
 *     'Emulated memory' access addresses should be checked for sanity.
 *     'Normal memory' accesses may fault, and the caller must arrange to
 *     detect and handle reentrancy into the emulator via recursive faults.
 *     Accesses may be unaligned and may cross page boundaries.
 *  2. If the access fails (cannot emulate, or a standard access faults) then
 *     it is up to the memop to propagate the fault to the guest VM via
 *     some out-of-band mechanism, unknown to the emulator. The memop signals
 *     failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
 *     then immediately bail.
 *  3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
 *     cmpxchg8b_emulated need support 8-byte accesses.
 *  4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
 */
/* Access completed successfully: continue emulation as normal. */
#define X86EMUL_CONTINUE        0
/* Access is unhandleable: bail from emulation and return error to caller. */
#define X86EMUL_UNHANDLEABLE    1
/* Terminate emulation but return success to the caller. */
#define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */
#define X86EMUL_RETRY_INSTR     3 /* retry the instruction for some reason */
#define X86EMUL_CMPXCHG_FAILED  4 /* cmpxchg did not see expected value */
#define X86EMUL_IO_NEEDED       5 /* IO is needed to complete emulation */
#define X86EMUL_INTERCEPTED     6 /* Intercepted by nested VMCB/VMCS */
 
/* x86-specific emulation flags */
#define X86EMUL_F_WRITE         BIT(0)
#define X86EMUL_F_FETCH         BIT(1)
#define X86EMUL_F_IMPLICIT      BIT(2)
#define X86EMUL_F_INVLPG        BIT(3)
 
struct x86_emulate_ops {
    void (*vm_bugged)(struct x86_emulate_ctxt *ctxt);
    /*
     * read_gpr: read a general purpose register (rax - r15)
     *
     * @reg: gpr number.
     */
    ulong (*read_gpr)(struct x86_emulate_ctxt *ctxt, unsigned reg);
    /*
     * write_gpr: write a general purpose register (rax - r15)
     *
     * @reg: gpr number.
     * @val: value to write.
     */
    void (*write_gpr)(struct x86_emulate_ctxt *ctxt, unsigned reg, ulong val);
    /*
     * read_std: Read bytes of standard (non-emulated/special) memory.
     *           Used for descriptor reading.
     *  @addr:  [IN ] Linear address from which to read.
     *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
     *  @bytes: [IN ] Number of bytes to read from memory.
     *  @system:[IN ] Whether the access is forced to be at CPL0.
     */
    int (*read_std)(struct x86_emulate_ctxt *ctxt,
            unsigned long addr, void *val,
            unsigned int bytes,
            struct x86_exception *fault, bool system);
 
    /*
     * write_std: Write bytes of standard (non-emulated/special) memory.
     *            Used for descriptor writing.
     *  @addr:  [IN ] Linear address to which to write.
     *  @val:   [OUT] Value write to memory, zero-extended to 'u_long'.
     *  @bytes: [IN ] Number of bytes to write to memory.
     *  @system:[IN ] Whether the access is forced to be at CPL0.
     */
    int (*write_std)(struct x86_emulate_ctxt *ctxt,
             unsigned long addr, void *val, unsigned int bytes,
             struct x86_exception *fault, bool system);
    /*
     * fetch: Read bytes of standard (non-emulated/special) memory.
     *        Used for instruction fetch.
     *  @addr:  [IN ] Linear address from which to read.
     *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
     *  @bytes: [IN ] Number of bytes to read from memory.
     */
    int (*fetch)(struct x86_emulate_ctxt *ctxt,
             unsigned long addr, void *val, unsigned int bytes,
             struct x86_exception *fault);
 
    /*
     * read_emulated: Read bytes from emulated/special memory area.
     *  @addr:  [IN ] Linear address from which to read.
     *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
     *  @bytes: [IN ] Number of bytes to read from memory.
     */
    int (*read_emulated)(struct x86_emulate_ctxt *ctxt,
                 unsigned long addr, void *val, unsigned int bytes,
                 struct x86_exception *fault);
 
    /*
     * write_emulated: Write bytes to emulated/special memory area.
     *  @addr:  [IN ] Linear address to which to write.
     *  @val:   [IN ] Value to write to memory (low-order bytes used as
     *                required).
     *  @bytes: [IN ] Number of bytes to write to memory.
     */
    int (*write_emulated)(struct x86_emulate_ctxt *ctxt,
                  unsigned long addr, const void *val,
                  unsigned int bytes,
                  struct x86_exception *fault);
 
    /*
     * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
     *                   emulated/special memory area.
     *  @addr:  [IN ] Linear address to access.
     *  @old:   [IN ] Value expected to be current at @addr.
     *  @new:   [IN ] Value to write to @addr.
     *  @bytes: [IN ] Number of bytes to access using CMPXCHG.
     */
    int (*cmpxchg_emulated)(struct x86_emulate_ctxt *ctxt,
                unsigned long addr,
                const void *old,
                const void *new,
                unsigned int bytes,
                struct x86_exception *fault);
    void (*invlpg)(struct x86_emulate_ctxt *ctxt, ulong addr);
 
    int (*pio_in_emulated)(struct x86_emulate_ctxt *ctxt,
                   int size, unsigned short port, void *val,
                   unsigned int count);
 
    int (*pio_out_emulated)(struct x86_emulate_ctxt *ctxt,
                int size, unsigned short port, const void *val,
                unsigned int count);
 
    bool (*get_segment)(struct x86_emulate_ctxt *ctxt, u16 *selector,
                struct desc_struct *desc, u32 *base3, int seg);
    void (*set_segment)(struct x86_emulate_ctxt *ctxt, u16 selector,
                struct desc_struct *desc, u32 base3, int seg);
    unsigned long (*get_cached_segment_base)(struct x86_emulate_ctxt *ctxt,
                         int seg);
    void (*get_gdt)(struct x86_emulate_ctxt *ctxt, struct desc_ptr *dt);
    void (*get_idt)(struct x86_emulate_ctxt *ctxt, struct desc_ptr *dt);
    void (*set_gdt)(struct x86_emulate_ctxt *ctxt, struct desc_ptr *dt);
    void (*set_idt)(struct x86_emulate_ctxt *ctxt, struct desc_ptr *dt);
    ulong (*get_cr)(struct x86_emulate_ctxt *ctxt, int cr);
    int (*set_cr)(struct x86_emulate_ctxt *ctxt, int cr, ulong val);
    int (*cpl)(struct x86_emulate_ctxt *ctxt);
    void (*get_dr)(struct x86_emulate_ctxt *ctxt, int dr, ulong *dest);
    int (*set_dr)(struct x86_emulate_ctxt *ctxt, int dr, ulong value);
    int (*set_msr_with_filter)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 data);
    int (*get_msr_with_filter)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 *pdata);
    int (*get_msr)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 *pdata);
    int (*check_pmc)(struct x86_emulate_ctxt *ctxt, u32 pmc);
    int (*read_pmc)(struct x86_emulate_ctxt *ctxt, u32 pmc, u64 *pdata);
    void (*halt)(struct x86_emulate_ctxt *ctxt);
    void (*wbinvd)(struct x86_emulate_ctxt *ctxt);
    int (*fix_hypercall)(struct x86_emulate_ctxt *ctxt);
    int (*intercept)(struct x86_emulate_ctxt *ctxt,
             struct x86_instruction_info *info,
             enum x86_intercept_stage stage);
 
    bool (*get_cpuid)(struct x86_emulate_ctxt *ctxt, u32 *eax, u32 *ebx,
              u32 *ecx, u32 *edx, bool exact_only);
    bool (*guest_has_movbe)(struct x86_emulate_ctxt *ctxt);
    bool (*guest_has_fxsr)(struct x86_emulate_ctxt *ctxt);
    bool (*guest_has_rdpid)(struct x86_emulate_ctxt *ctxt);
 
    void (*set_nmi_mask)(struct x86_emulate_ctxt *ctxt, bool masked);
 
    bool (*is_smm)(struct x86_emulate_ctxt *ctxt);
    bool (*is_guest_mode)(struct x86_emulate_ctxt *ctxt);
    int (*leave_smm)(struct x86_emulate_ctxt *ctxt);
    void (*triple_fault)(struct x86_emulate_ctxt *ctxt);
    int (*set_xcr)(struct x86_emulate_ctxt *ctxt, u32 index, u64 xcr);
 
    gva_t (*get_untagged_addr)(struct x86_emulate_ctxt *ctxt, gva_t addr,
                   unsigned int flags);
};
 
/* Type, address-of, and value of an instruction's operand. */
struct operand {
    enum { OP_REG, OP_MEM, OP_MEM_STR, OP_IMM, OP_XMM, OP_MM, OP_NONE } type;
    unsigned int bytes;
    unsigned int count;
    union {
        unsigned long orig_val;
        u64 orig_val64;
    };
    union {
        unsigned long *reg;
        struct segmented_address {
            ulong ea;
            unsigned seg;
        } mem;
        unsigned xmm;
        unsigned mm;
    } addr;
    union {
        unsigned long val;
        u64 val64;
        char valptr[sizeof(sse128_t)];
        sse128_t vec_val;
        u64 mm_val;
        void *data;
    };
};
 
struct fetch_cache {
    u8 data[15];
    u8 *ptr;
    u8 *end;
};
 
struct read_cache {
    u8 data[1024];
    unsigned long pos;
    unsigned long end;
};
 
/* Execution mode, passed to the emulator. */
enum x86emul_mode {
    X86EMUL_MODE_REAL,  /* Real mode.             */
    X86EMUL_MODE_VM86,  /* Virtual 8086 mode.     */
    X86EMUL_MODE_PROT16,    /* 16-bit protected mode. */
    X86EMUL_MODE_PROT32,    /* 32-bit protected mode. */
    X86EMUL_MODE_PROT64,    /* 64-bit (long) mode.    */
};
 
/*
 * fastop functions are declared as taking a never-defined fastop parameter,
 * so they can't be called from C directly.
 */
struct fastop;
 
typedef void (*fastop_t)(struct fastop *);
 
/*
 * The emulator's _regs array tracks only the GPRs, i.e. excludes RIP.  RIP is
 * tracked/accessed via _eip, and except for RIP relative addressing, which
 * also uses _eip, RIP cannot be a register operand nor can it be an operand in
 * a ModRM or SIB byte.
 */
#ifdef CONFIG_X86_64
#define NR_EMULATOR_GPRS    16
#else
#define NR_EMULATOR_GPRS    8
#endif
 
struct x86_emulate_ctxt {
    void *vcpu;
    const struct x86_emulate_ops *ops;
 
    /* Register state before/after emulation. */
    unsigned long eflags;
    unsigned long eip; /* eip before instruction emulation */
    /* Emulated execution mode, represented by an X86EMUL_MODE value. */
    enum x86emul_mode mode;
 
    /* interruptibility state, as a result of execution of STI or MOV SS */
    int interruptibility;
 
    bool perm_ok; /* do not check permissions if true */
    bool tf;    /* TF value before instruction (after for syscall/sysret) */
 
    bool have_exception;
    struct x86_exception exception;
 
    /* GPA available */
    bool gpa_available;
    gpa_t gpa_val;
 
    /*
     * decode cache
     */
 
    /* current opcode length in bytes */
    u8 opcode_len;
    u8 b;
    u8 intercept;
    u8 op_bytes;
    u8 ad_bytes;
    union {
        int (*execute)(struct x86_emulate_ctxt *ctxt);
        fastop_t fop;
    };
    int (*check_perm)(struct x86_emulate_ctxt *ctxt);
 
    bool rip_relative;
    u8 rex_prefix;
    u8 lock_prefix;
    u8 rep_prefix;
    /* bitmaps of registers in _regs[] that can be read */
    u16 regs_valid;
    /* bitmaps of registers in _regs[] that have been written */
    u16 regs_dirty;
    /* modrm */
    u8 modrm;
    u8 modrm_mod;
    u8 modrm_reg;
    u8 modrm_rm;
    u8 modrm_seg;
    u8 seg_override;
    u64 d;
    unsigned long _eip;
 
    /* Here begins the usercopy section. */
    struct operand src;
    struct operand src2;
    struct operand dst;
    struct operand memop;
    unsigned long _regs[NR_EMULATOR_GPRS];
    struct operand *memopp;
    struct fetch_cache fetch;
    struct read_cache io_read;
    struct read_cache mem_read;
    bool is_branch;
};
 
#define KVM_EMULATOR_BUG_ON(cond, ctxt)     \
({                      \
    int __ret = (cond);         \
                        \
    if (WARN_ON_ONCE(__ret))        \
        ctxt->ops->vm_bugged(ctxt); \
    unlikely(__ret);            \
})
 
/* Repeat String Operation Prefix */
#define REPE_PREFIX 0xf3
#define REPNE_PREFIX    0xf2
 
/* CPUID vendors */
#define X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx 0x68747541
#define X86EMUL_CPUID_VENDOR_AuthenticAMD_ecx 0x444d4163
#define X86EMUL_CPUID_VENDOR_AuthenticAMD_edx 0x69746e65
 
#define X86EMUL_CPUID_VENDOR_AMDisbetterI_ebx 0x69444d41
#define X86EMUL_CPUID_VENDOR_AMDisbetterI_ecx 0x21726574
#define X86EMUL_CPUID_VENDOR_AMDisbetterI_edx 0x74656273
 
#define X86EMUL_CPUID_VENDOR_HygonGenuine_ebx 0x6f677948
#define X86EMUL_CPUID_VENDOR_HygonGenuine_ecx 0x656e6975
#define X86EMUL_CPUID_VENDOR_HygonGenuine_edx 0x6e65476e
 
#define X86EMUL_CPUID_VENDOR_GenuineIntel_ebx 0x756e6547
#define X86EMUL_CPUID_VENDOR_GenuineIntel_ecx 0x6c65746e
#define X86EMUL_CPUID_VENDOR_GenuineIntel_edx 0x49656e69
 
#define X86EMUL_CPUID_VENDOR_CentaurHauls_ebx 0x746e6543
#define X86EMUL_CPUID_VENDOR_CentaurHauls_ecx 0x736c7561
#define X86EMUL_CPUID_VENDOR_CentaurHauls_edx 0x48727561
 
static inline bool is_guest_vendor_intel(u32 ebx, u32 ecx, u32 edx)
{
    return ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx &&
           ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx &&
           edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx;
}
 
static inline bool is_guest_vendor_amd(u32 ebx, u32 ecx, u32 edx)
{
    return (ebx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx &&
        ecx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ecx &&
        edx == X86EMUL_CPUID_VENDOR_AuthenticAMD_edx) ||
           (ebx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ebx &&
        ecx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ecx &&
        edx == X86EMUL_CPUID_VENDOR_AMDisbetterI_edx);
}
 
static inline bool is_guest_vendor_hygon(u32 ebx, u32 ecx, u32 edx)
{
    return ebx == X86EMUL_CPUID_VENDOR_HygonGenuine_ebx &&
           ecx == X86EMUL_CPUID_VENDOR_HygonGenuine_ecx &&
           edx == X86EMUL_CPUID_VENDOR_HygonGenuine_edx;
}
 
enum x86_intercept_stage {
    X86_ICTP_NONE = 0,   /* Allow zero-init to not match anything */
    X86_ICPT_PRE_EXCEPT,
    X86_ICPT_POST_EXCEPT,
    X86_ICPT_POST_MEMACCESS,
};
 
enum x86_intercept {
    x86_intercept_none,
    x86_intercept_cr_read,
    x86_intercept_cr_write,
    x86_intercept_clts,
    x86_intercept_lmsw,
    x86_intercept_smsw,
    x86_intercept_dr_read,
    x86_intercept_dr_write,
    x86_intercept_lidt,
    x86_intercept_sidt,
    x86_intercept_lgdt,
    x86_intercept_sgdt,
    x86_intercept_lldt,
    x86_intercept_sldt,
    x86_intercept_ltr,
    x86_intercept_str,
    x86_intercept_rdtsc,
    x86_intercept_rdpmc,
    x86_intercept_pushf,
    x86_intercept_popf,
    x86_intercept_cpuid,
    x86_intercept_rsm,
    x86_intercept_iret,
    x86_intercept_intn,
    x86_intercept_invd,
    x86_intercept_pause,
    x86_intercept_hlt,
    x86_intercept_invlpg,
    x86_intercept_invlpga,
    x86_intercept_vmrun,
    x86_intercept_vmload,
    x86_intercept_vmsave,
    x86_intercept_vmmcall,
    x86_intercept_stgi,
    x86_intercept_clgi,
    x86_intercept_skinit,
    x86_intercept_rdtscp,
    x86_intercept_rdpid,
    x86_intercept_icebp,
    x86_intercept_wbinvd,
    x86_intercept_monitor,
    x86_intercept_mwait,
    x86_intercept_rdmsr,
    x86_intercept_wrmsr,
    x86_intercept_in,
    x86_intercept_ins,
    x86_intercept_out,
    x86_intercept_outs,
    x86_intercept_xsetbv,
 
    nr_x86_intercepts
};
 
/* Host execution mode. */
#if defined(CONFIG_X86_32)
#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
#elif defined(CONFIG_X86_64)
#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
#endif
 
int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len, int emulation_type);
bool x86_page_table_writing_insn(struct x86_emulate_ctxt *ctxt);
#define EMULATION_FAILED -1
#define EMULATION_OK 0
#define EMULATION_RESTART 1
#define EMULATION_INTERCEPTED 2
void init_decode_cache(struct x86_emulate_ctxt *ctxt);
int x86_emulate_insn(struct x86_emulate_ctxt *ctxt);
int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
             u16 tss_selector, int idt_index, int reason,
             bool has_error_code, u32 error_code);
int emulate_int_real(struct x86_emulate_ctxt *ctxt, int irq);
void emulator_invalidate_register_cache(struct x86_emulate_ctxt *ctxt);
void emulator_writeback_register_cache(struct x86_emulate_ctxt *ctxt);
bool emulator_can_use_gpa(struct x86_emulate_ctxt *ctxt);
 
static inline ulong reg_read(struct x86_emulate_ctxt *ctxt, unsigned nr)
{
    if (KVM_EMULATOR_BUG_ON(nr >= NR_EMULATOR_GPRS, ctxt))
        nr &= NR_EMULATOR_GPRS - 1;
 
    if (!(ctxt->regs_valid & (1 << nr))) {
        ctxt->regs_valid |= 1 << nr;
        ctxt->_regs[nr] = ctxt->ops->read_gpr(ctxt, nr);
    }
    return ctxt->_regs[nr];
}
 
static inline ulong *reg_write(struct x86_emulate_ctxt *ctxt, unsigned nr)
{
    if (KVM_EMULATOR_BUG_ON(nr >= NR_EMULATOR_GPRS, ctxt))
        nr &= NR_EMULATOR_GPRS - 1;
 
    BUILD_BUG_ON(sizeof(ctxt->regs_dirty) * BITS_PER_BYTE < NR_EMULATOR_GPRS);
    BUILD_BUG_ON(sizeof(ctxt->regs_valid) * BITS_PER_BYTE < NR_EMULATOR_GPRS);
 
    ctxt->regs_valid |= 1 << nr;
    ctxt->regs_dirty |= 1 << nr;
    return &ctxt->_regs[nr];
}
 
static inline ulong *reg_rmw(struct x86_emulate_ctxt *ctxt, unsigned nr)
{
    reg_read(ctxt, nr);
    return reg_write(ctxt, nr);
}
 
#endif /* _ASM_X86_KVM_X86_EMULATE_H */