arch/x86/include/asm/kvm_x86_emulate.h

   1 /******************************************************************************
   2  * x86_emulate.h
   3  *
   4  * Generic x86 (32-bit and 64-bit) instruction decoder and emulator.
   5  *
   6  * Copyright (c) 2005 Keir Fraser
   7  *
   8  * From: xen-unstable 10676:af9809f51f81a3c43f276f00c81a52ef558afda4
   9  */
  10
  11 #ifndef _ASM_X86_KVM_X86_EMULATE_H
  12 #define _ASM_X86_KVM_X86_EMULATE_H
  13
  14 struct x86_emulate_ctxt;
  15
  16 /*
  17  * x86_emulate_ops:
  18  *
  19  * These operations represent the instruction emulator's interface to memory.
  20  * There are two categories of operation: those that act on ordinary memory
  21  * regions (*_std), and those that act on memory regions known to require
  22  * special treatment or emulation (*_emulated).
  23  *
  24  * The emulator assumes that an instruction accesses only one 'emulated memory'
  25  * location, that this location is the given linear faulting address (cr2), and
  26  * that this is one of the instruction's data operands. Instruction fetches and
  27  * stack operations are assumed never to access emulated memory. The emulator
  28  * automatically deduces which operand of a string-move operation is accessing
  29  * emulated memory, and assumes that the other operand accesses normal memory.
  30  *
  31  * NOTES:
  32  *  1. The emulator isn't very smart about emulated vs. standard memory.
  33  *     'Emulated memory' access addresses should be checked for sanity.
  34  *     'Normal memory' accesses may fault, and the caller must arrange to
  35  *     detect and handle reentrancy into the emulator via recursive faults.
  36  *     Accesses may be unaligned and may cross page boundaries.
  37  *  2. If the access fails (cannot emulate, or a standard access faults) then
  38  *     it is up to the memop to propagate the fault to the guest VM via
  39  *     some out-of-band mechanism, unknown to the emulator. The memop signals
  40  *     failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
  41  *     then immediately bail.
  42  *  3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
  43  *     cmpxchg8b_emulated need support 8-byte accesses.
  44  *  4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
  45  */
  46 /* Access completed successfully: continue emulation as normal. */
  47 #define X86EMUL_CONTINUE        0
  48 /* Access is unhandleable: bail from emulation and return error to caller. */
  49 #define X86EMUL_UNHANDLEABLE    1
  50 /* Terminate emulation but return success to the caller. */
  51 #define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */
  52 #define X86EMUL_RETRY_INSTR     2 /* retry the instruction for some reason */
  53 #define X86EMUL_CMPXCHG_FAILED  2 /* cmpxchg did not see expected value */
  54 struct x86_emulate_ops {
  55         /*
  56          * read_std: Read bytes of standard (non-emulated/special) memory.
  57          *           Used for instruction fetch, stack operations, and others.
  58          *  @addr:  [IN ] Linear address from which to read.
  59          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  60          *  @bytes: [IN ] Number of bytes to read from memory.
  61          */
  62         int (*read_std)(unsigned long addr, void *val,
  63                         unsigned int bytes, struct kvm_vcpu *vcpu);
  64
  65         /*
  66          * read_emulated: Read bytes from emulated/special memory area.
  67          *  @addr:  [IN ] Linear address from which to read.
  68          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  69          *  @bytes: [IN ] Number of bytes to read from memory.
  70          */
  71         int (*read_emulated)(unsigned long addr,
  72                              void *val,
  73                              unsigned int bytes,
  74                              struct kvm_vcpu *vcpu);
  75
  76         /*
  77          * write_emulated: Read bytes from emulated/special memory area.
  78          *  @addr:  [IN ] Linear address to which to write.
  79          *  @val:   [IN ] Value to write to memory (low-order bytes used as
  80          *                required).
  81          *  @bytes: [IN ] Number of bytes to write to memory.
  82          */
  83         int (*write_emulated)(unsigned long addr,
  84                               const void *val,
  85                               unsigned int bytes,
  86                               struct kvm_vcpu *vcpu);
  87
  88         /*
  89          * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
  90          *                   emulated/special memory area.
  91          *  @addr:  [IN ] Linear address to access.
  92          *  @old:   [IN ] Value expected to be current at @addr.
  93          *  @new:   [IN ] Value to write to @addr.
  94          *  @bytes: [IN ] Number of bytes to access using CMPXCHG.
  95          */
  96         int (*cmpxchg_emulated)(unsigned long addr,
  97                                 const void *old,
  98                                 const void *new,
  99                                 unsigned int bytes,
 100                                 struct kvm_vcpu *vcpu);
 101
 102 };
 103
 104 /* Type, address-of, and value of an instruction's operand. */
 105 struct operand {
 106         enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
 107         unsigned int bytes;
 108         unsigned long val, orig_val, *ptr;
 109 };
 110
 111 struct fetch_cache {
 112         u8 data[15];
 113         unsigned long start;
 114         unsigned long end;
 115 };
 116
 117 struct decode_cache {
 118         u8 twobyte;
 119         u8 b;
 120         u8 lock_prefix;
 121         u8 rep_prefix;
 122         u8 op_bytes;
 123         u8 ad_bytes;
 124         u8 rex_prefix;
 125         struct operand src;
 126         struct operand src2;
 127         struct operand dst;
 128         bool has_seg_override;
 129         u8 seg_override;
 130         unsigned int d;
 131         unsigned long regs[NR_VCPU_REGS];
 132         unsigned long eip;
 133         /* modrm */
 134         u8 modrm;
 135         u8 modrm_mod;
 136         u8 modrm_reg;
 137         u8 modrm_rm;
 138         u8 use_modrm_ea;
 139         bool rip_relative;
 140         unsigned long modrm_ea;
 141         void *modrm_ptr;
 142         unsigned long modrm_val;
 143         struct fetch_cache fetch;
 144 };
 145
 146 struct x86_emulate_ctxt {
 147         /* Register state before/after emulation. */
 148         struct kvm_vcpu *vcpu;
 149
 150         unsigned long eflags;
 151         /* Emulated execution mode, represented by an X86EMUL_MODE value. */
 152         int mode;
 153         u32 cs_base;
 154
 155         /* decode cache */
 156         struct decode_cache decode;
 157 };
 158
 159 /* Repeat String Operation Prefix */
 160 #define REPE_PREFIX     1
 161 #define REPNE_PREFIX    2
 162
 163 /* Execution mode, passed to the emulator. */
 164 #define X86EMUL_MODE_REAL     0 /* Real mode.             */
 165 #define X86EMUL_MODE_PROT16   2 /* 16-bit protected mode. */
 166 #define X86EMUL_MODE_PROT32   4 /* 32-bit protected mode. */
 167 #define X86EMUL_MODE_PROT64   8 /* 64-bit (long) mode.    */
 168
 169 /* Host execution mode. */
 170 #if defined(CONFIG_X86_32)
 171 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
 172 #elif defined(CONFIG_X86_64)
 173 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
 174 #endif
 175
 176 int x86_decode_insn(struct x86_emulate_ctxt *ctxt,
 177                     struct x86_emulate_ops *ops);
 178 int x86_emulate_insn(struct x86_emulate_ctxt *ctxt,
 179                      struct x86_emulate_ops *ops);
 180
 181 #endif /* _ASM_X86_KVM_X86_EMULATE_H */