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 #include <asm/desc_defs.h>
  15
  16 struct x86_emulate_ctxt;
  17
  18 /*
  19  * x86_emulate_ops:
  20  *
  21  * These operations represent the instruction emulator's interface to memory.
  22  * There are two categories of operation: those that act on ordinary memory
  23  * regions (*_std), and those that act on memory regions known to require
  24  * special treatment or emulation (*_emulated).
  25  *
  26  * The emulator assumes that an instruction accesses only one 'emulated memory'
  27  * location, that this location is the given linear faulting address (cr2), and
  28  * that this is one of the instruction's data operands. Instruction fetches and
  29  * stack operations are assumed never to access emulated memory. The emulator
  30  * automatically deduces which operand of a string-move operation is accessing
  31  * emulated memory, and assumes that the other operand accesses normal memory.
  32  *
  33  * NOTES:
  34  *  1. The emulator isn't very smart about emulated vs. standard memory.
  35  *     'Emulated memory' access addresses should be checked for sanity.
  36  *     'Normal memory' accesses may fault, and the caller must arrange to
  37  *     detect and handle reentrancy into the emulator via recursive faults.
  38  *     Accesses may be unaligned and may cross page boundaries.
  39  *  2. If the access fails (cannot emulate, or a standard access faults) then
  40  *     it is up to the memop to propagate the fault to the guest VM via
  41  *     some out-of-band mechanism, unknown to the emulator. The memop signals
  42  *     failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
  43  *     then immediately bail.
  44  *  3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
  45  *     cmpxchg8b_emulated need support 8-byte accesses.
  46  *  4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
  47  */
  48 /* Access completed successfully: continue emulation as normal. */
  49 #define X86EMUL_CONTINUE        0
  50 /* Access is unhandleable: bail from emulation and return error to caller. */
  51 #define X86EMUL_UNHANDLEABLE    1
  52 /* Terminate emulation but return success to the caller. */
  53 #define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */
  54 #define X86EMUL_RETRY_INSTR     3 /* retry the instruction for some reason */
  55 #define X86EMUL_CMPXCHG_FAILED  4 /* cmpxchg did not see expected value */
  56 #define X86EMUL_IO_NEEDED       5 /* IO is needed to complete emulation */
  57
  58 struct x86_emulate_ops {
  59         /*
  60          * read_std: Read bytes of standard (non-emulated/special) memory.
  61          *           Used for descriptor reading.
  62          *  @addr:  [IN ] Linear address from which to read.
  63          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  64          *  @bytes: [IN ] Number of bytes to read from memory.
  65          */
  66         int (*read_std)(unsigned long addr, void *val,
  67                         unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
  68
  69         /*
  70          * write_std: Write bytes of standard (non-emulated/special) memory.
  71          *            Used for descriptor writing.
  72          *  @addr:  [IN ] Linear address to which to write.
  73          *  @val:   [OUT] Value write to memory, zero-extended to 'u_long'.
  74          *  @bytes: [IN ] Number of bytes to write to memory.
  75          */
  76         int (*write_std)(unsigned long addr, void *val,
  77                          unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
  78         /*
  79          * fetch: Read bytes of standard (non-emulated/special) memory.
  80          *        Used for instruction fetch.
  81          *  @addr:  [IN ] Linear address from which to read.
  82          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  83          *  @bytes: [IN ] Number of bytes to read from memory.
  84          */
  85         int (*fetch)(unsigned long addr, void *val,
  86                         unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
  87
  88         /*
  89          * read_emulated: Read bytes from emulated/special memory area.
  90          *  @addr:  [IN ] Linear address from which to read.
  91          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  92          *  @bytes: [IN ] Number of bytes to read from memory.
  93          */
  94         int (*read_emulated)(unsigned long addr,
  95                              void *val,
  96                              unsigned int bytes,
  97                              unsigned int *error,
  98                              struct kvm_vcpu *vcpu);
  99
 100         /*
 101          * write_emulated: Write bytes to emulated/special memory area.
 102          *  @addr:  [IN ] Linear address to which to write.
 103          *  @val:   [IN ] Value to write to memory (low-order bytes used as
 104          *                required).
 105          *  @bytes: [IN ] Number of bytes to write to memory.
 106          */
 107         int (*write_emulated)(unsigned long addr,
 108                               const void *val,
 109                               unsigned int bytes,
 110                               unsigned int *error,
 111                               struct kvm_vcpu *vcpu);
 112
 113         /*
 114          * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
 115          *                   emulated/special memory area.
 116          *  @addr:  [IN ] Linear address to access.
 117          *  @old:   [IN ] Value expected to be current at @addr.
 118          *  @new:   [IN ] Value to write to @addr.
 119          *  @bytes: [IN ] Number of bytes to access using CMPXCHG.
 120          */
 121         int (*cmpxchg_emulated)(unsigned long addr,
 122                                 const void *old,
 123                                 const void *new,
 124                                 unsigned int bytes,
 125                                 unsigned int *error,
 126                                 struct kvm_vcpu *vcpu);
 127
 128         int (*pio_in_emulated)(int size, unsigned short port, void *val,
 129                                unsigned int count, struct kvm_vcpu *vcpu);
 130
 131         int (*pio_out_emulated)(int size, unsigned short port, const void *val,
 132                                 unsigned int count, struct kvm_vcpu *vcpu);
 133
 134         bool (*get_cached_descriptor)(struct desc_struct *desc,
 135                                       int seg, struct kvm_vcpu *vcpu);
 136         void (*set_cached_descriptor)(struct desc_struct *desc,
 137                                       int seg, struct kvm_vcpu *vcpu);
 138         u16 (*get_segment_selector)(int seg, struct kvm_vcpu *vcpu);
 139         void (*set_segment_selector)(u16 sel, int seg, struct kvm_vcpu *vcpu);
 140         unsigned long (*get_cached_segment_base)(int seg, struct kvm_vcpu *vcpu);
 141         void (*get_gdt)(struct desc_ptr *dt, struct kvm_vcpu *vcpu);
 142         ulong (*get_cr)(int cr, struct kvm_vcpu *vcpu);
 143         int (*set_cr)(int cr, ulong val, struct kvm_vcpu *vcpu);
 144         int (*cpl)(struct kvm_vcpu *vcpu);
 145         int (*get_dr)(int dr, unsigned long *dest, struct kvm_vcpu *vcpu);
 146         int (*set_dr)(int dr, unsigned long value, struct kvm_vcpu *vcpu);
 147         int (*set_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
 148         int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
 149 };
 150
 151 /* Type, address-of, and value of an instruction's operand. */
 152 struct operand {
 153         enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
 154         unsigned int bytes;
 155         union {
 156                 unsigned long orig_val;
 157                 u64 orig_val64;
 158         };
 159         unsigned long *ptr;
 160         union {
 161                 unsigned long val;
 162                 u64 val64;
 163                 char valptr[sizeof(unsigned long) + 2];
 164         };
 165 };
 166
 167 struct fetch_cache {
 168         u8 data[15];
 169         unsigned long start;
 170         unsigned long end;
 171 };
 172
 173 struct read_cache {
 174         u8 data[1024];
 175         unsigned long pos;
 176         unsigned long end;
 177 };
 178
 179 struct decode_cache {
 180         u8 twobyte;
 181         u8 b;
 182         u8 lock_prefix;
 183         u8 rep_prefix;
 184         u8 op_bytes;
 185         u8 ad_bytes;
 186         u8 rex_prefix;
 187         struct operand src;
 188         struct operand src2;
 189         struct operand dst;
 190         bool has_seg_override;
 191         u8 seg_override;
 192         unsigned int d;
 193         unsigned long regs[NR_VCPU_REGS];
 194         unsigned long eip;
 195         /* modrm */
 196         u8 modrm;
 197         u8 modrm_mod;
 198         u8 modrm_reg;
 199         u8 modrm_rm;
 200         u8 use_modrm_ea;
 201         bool rip_relative;
 202         unsigned long modrm_ea;
 203         void *modrm_ptr;
 204         unsigned long modrm_val;
 205         struct fetch_cache fetch;
 206         struct read_cache io_read;
 207         struct read_cache mem_read;
 208 };
 209
 210 struct x86_emulate_ctxt {
 211         struct x86_emulate_ops *ops;
 212
 213         /* Register state before/after emulation. */
 214         struct kvm_vcpu *vcpu;
 215
 216         unsigned long eflags;
 217         unsigned long eip; /* eip before instruction emulation */
 218         /* Emulated execution mode, represented by an X86EMUL_MODE value. */
 219         int mode;
 220         u32 cs_base;
 221
 222         /* interruptibility state, as a result of execution of STI or MOV SS */
 223         int interruptibility;
 224
 225         bool restart; /* restart string instruction after writeback */
 226
 227         int exception; /* exception that happens during emulation or -1 */
 228         u32 error_code; /* error code for exception */
 229         bool error_code_valid;
 230         unsigned long cr2; /* faulted address in case of #PF */
 231
 232         /* decode cache */
 233         struct decode_cache decode;
 234 };
 235
 236 /* Repeat String Operation Prefix */
 237 #define REPE_PREFIX     1
 238 #define REPNE_PREFIX    2
 239
 240 /* Execution mode, passed to the emulator. */
 241 #define X86EMUL_MODE_REAL     0 /* Real mode.             */
 242 #define X86EMUL_MODE_VM86     1 /* Virtual 8086 mode.     */
 243 #define X86EMUL_MODE_PROT16   2 /* 16-bit protected mode. */
 244 #define X86EMUL_MODE_PROT32   4 /* 32-bit protected mode. */
 245 #define X86EMUL_MODE_PROT64   8 /* 64-bit (long) mode.    */
 246
 247 /* Host execution mode. */
 248 #if defined(CONFIG_X86_32)
 249 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
 250 #elif defined(CONFIG_X86_64)
 251 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
 252 #endif
 253
 254 int x86_decode_insn(struct x86_emulate_ctxt *ctxt);
 255 int x86_emulate_insn(struct x86_emulate_ctxt *ctxt);
 256 int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
 257                          u16 tss_selector, int reason,
 258                          bool has_error_code, u32 error_code);
 259
 260 #endif /* _ASM_X86_KVM_X86_EMULATE_H */