arch/x86/include/asm/kvm_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 descriptor reading.
  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, u32 *error);
  64
  65         /*
  66          * fetch: Read bytes of standard (non-emulated/special) memory.
  67          *        Used for instruction fetch.
  68          *  @addr:  [IN ] Linear address from which to read.
  69          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  70          *  @bytes: [IN ] Number of bytes to read from memory.
  71          */
  72         int (*fetch)(unsigned long addr, void *val,
  73                         unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
  74
  75         /*
  76          * read_emulated: Read bytes from emulated/special memory area.
  77          *  @addr:  [IN ] Linear address from which to read.
  78          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  79          *  @bytes: [IN ] Number of bytes to read from memory.
  80          */
  81         int (*read_emulated)(unsigned long addr,
  82                              void *val,
  83                              unsigned int bytes,
  84                              struct kvm_vcpu *vcpu);
  85
  86         /*
  87          * write_emulated: Write bytes to emulated/special memory area.
  88          *  @addr:  [IN ] Linear address to which to write.
  89          *  @val:   [IN ] Value to write to memory (low-order bytes used as
  90          *                required).
  91          *  @bytes: [IN ] Number of bytes to write to memory.
  92          */
  93         int (*write_emulated)(unsigned long addr,
  94                               const void *val,
  95                               unsigned int bytes,
  96                               struct kvm_vcpu *vcpu);
  97
  98         /*
  99          * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
 100          *                   emulated/special memory area.
 101          *  @addr:  [IN ] Linear address to access.
 102          *  @old:   [IN ] Value expected to be current at @addr.
 103          *  @new:   [IN ] Value to write to @addr.
 104          *  @bytes: [IN ] Number of bytes to access using CMPXCHG.
 105          */
 106         int (*cmpxchg_emulated)(unsigned long addr,
 107                                 const void *old,
 108                                 const void *new,
 109                                 unsigned int bytes,
 110                                 struct kvm_vcpu *vcpu);
 111
 112 };
 113
 114 /* Type, address-of, and value of an instruction's operand. */
 115 struct operand {
 116         enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
 117         unsigned int bytes;
 118         unsigned long val, orig_val, *ptr;
 119 };
 120
 121 struct fetch_cache {
 122         u8 data[15];
 123         unsigned long start;
 124         unsigned long end;
 125 };
 126
 127 struct decode_cache {
 128         u8 twobyte;
 129         u8 b;
 130         u8 lock_prefix;
 131         u8 rep_prefix;
 132         u8 op_bytes;
 133         u8 ad_bytes;
 134         u8 rex_prefix;
 135         struct operand src;
 136         struct operand src2;
 137         struct operand dst;
 138         bool has_seg_override;
 139         u8 seg_override;
 140         unsigned int d;
 141         unsigned long regs[NR_VCPU_REGS];
 142         unsigned long eip, eip_orig;
 143         /* modrm */
 144         u8 modrm;
 145         u8 modrm_mod;
 146         u8 modrm_reg;
 147         u8 modrm_rm;
 148         u8 use_modrm_ea;
 149         bool rip_relative;
 150         unsigned long modrm_ea;
 151         void *modrm_ptr;
 152         unsigned long modrm_val;
 153         struct fetch_cache fetch;
 154 };
 155
 156 #define X86_SHADOW_INT_MOV_SS  1
 157 #define X86_SHADOW_INT_STI     2
 158
 159 struct x86_emulate_ctxt {
 160         /* Register state before/after emulation. */
 161         struct kvm_vcpu *vcpu;
 162
 163         unsigned long eflags;
 164         /* Emulated execution mode, represented by an X86EMUL_MODE value. */
 165         int mode;
 166         u32 cs_base;
 167
 168         /* interruptibility state, as a result of execution of STI or MOV SS */
 169         int interruptibility;
 170
 171         /* decode cache */
 172         struct decode_cache decode;
 173 };
 174
 175 /* Repeat String Operation Prefix */
 176 #define REPE_PREFIX     1
 177 #define REPNE_PREFIX    2
 178
 179 /* Execution mode, passed to the emulator. */
 180 #define X86EMUL_MODE_REAL     0 /* Real mode.             */
 181 #define X86EMUL_MODE_VM86     1 /* Virtual 8086 mode.     */
 182 #define X86EMUL_MODE_PROT16   2 /* 16-bit protected mode. */
 183 #define X86EMUL_MODE_PROT32   4 /* 32-bit protected mode. */
 184 #define X86EMUL_MODE_PROT64   8 /* 64-bit (long) mode.    */
 185
 186 /* Host execution mode. */
 187 #if defined(CONFIG_X86_32)
 188 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
 189 #elif defined(CONFIG_X86_64)
 190 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
 191 #endif
 192
 193 int x86_decode_insn(struct x86_emulate_ctxt *ctxt,
 194                     struct x86_emulate_ops *ops);
 195 int x86_emulate_insn(struct x86_emulate_ctxt *ctxt,
 196                      struct x86_emulate_ops *ops);
 197
 198 #endif /* _ASM_X86_KVM_X86_EMULATE_H */