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     2 /* retry the instruction for some reason */
  55 #define X86EMUL_CMPXCHG_FAILED  2 /* cmpxchg did not see expected value */
  56 struct x86_emulate_ops {
  57         /*
  58          * read_std: Read bytes of standard (non-emulated/special) memory.
  59          *           Used for descriptor reading.
  60          *  @addr:  [IN ] Linear address from which to read.
  61          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  62          *  @bytes: [IN ] Number of bytes to read from memory.
  63          */
  64         int (*read_std)(unsigned long addr, void *val,
  65                         unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
  66
  67         /*
  68          * write_std: Write bytes of standard (non-emulated/special) memory.
  69          *            Used for descriptor writing.
  70          *  @addr:  [IN ] Linear address to which to write.
  71          *  @val:   [OUT] Value write to memory, zero-extended to 'u_long'.
  72          *  @bytes: [IN ] Number of bytes to write to memory.
  73          */
  74         int (*write_std)(unsigned long addr, void *val,
  75                          unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
  76         /*
  77          * fetch: Read bytes of standard (non-emulated/special) memory.
  78          *        Used for instruction fetch.
  79          *  @addr:  [IN ] Linear address from which to read.
  80          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  81          *  @bytes: [IN ] Number of bytes to read from memory.
  82          */
  83         int (*fetch)(unsigned long addr, void *val,
  84                         unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
  85
  86         /*
  87          * read_emulated: Read bytes from emulated/special memory area.
  88          *  @addr:  [IN ] Linear address from which to read.
  89          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  90          *  @bytes: [IN ] Number of bytes to read from memory.
  91          */
  92         int (*read_emulated)(unsigned long addr,
  93                              void *val,
  94                              unsigned int bytes,
  95                              struct kvm_vcpu *vcpu);
  96
  97         /*
  98          * write_emulated: Write bytes to emulated/special memory area.
  99          *  @addr:  [IN ] Linear address to which to write.
 100          *  @val:   [IN ] Value to write to memory (low-order bytes used as
 101          *                required).
 102          *  @bytes: [IN ] Number of bytes to write to memory.
 103          */
 104         int (*write_emulated)(unsigned long addr,
 105                               const void *val,
 106                               unsigned int bytes,
 107                               struct kvm_vcpu *vcpu);
 108
 109         /*
 110          * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
 111          *                   emulated/special memory area.
 112          *  @addr:  [IN ] Linear address to access.
 113          *  @old:   [IN ] Value expected to be current at @addr.
 114          *  @new:   [IN ] Value to write to @addr.
 115          *  @bytes: [IN ] Number of bytes to access using CMPXCHG.
 116          */
 117         int (*cmpxchg_emulated)(unsigned long addr,
 118                                 const void *old,
 119                                 const void *new,
 120                                 unsigned int bytes,
 121                                 struct kvm_vcpu *vcpu);
 122
 123         int (*pio_in_emulated)(int size, unsigned short port, void *val,
 124                                unsigned int count, struct kvm_vcpu *vcpu);
 125
 126         int (*pio_out_emulated)(int size, unsigned short port, const void *val,
 127                                 unsigned int count, struct kvm_vcpu *vcpu);
 128
 129         bool (*get_cached_descriptor)(struct desc_struct *desc,
 130                                       int seg, struct kvm_vcpu *vcpu);
 131         void (*set_cached_descriptor)(struct desc_struct *desc,
 132                                       int seg, struct kvm_vcpu *vcpu);
 133         u16 (*get_segment_selector)(int seg, struct kvm_vcpu *vcpu);
 134         void (*set_segment_selector)(u16 sel, int seg, struct kvm_vcpu *vcpu);
 135         void (*get_gdt)(struct desc_ptr *dt, struct kvm_vcpu *vcpu);
 136         ulong (*get_cr)(int cr, struct kvm_vcpu *vcpu);
 137         void (*set_cr)(int cr, ulong val, struct kvm_vcpu *vcpu);
 138         int (*cpl)(struct kvm_vcpu *vcpu);
 139         void (*set_rflags)(struct kvm_vcpu *vcpu, unsigned long rflags);
 140 };
 141
 142 /* Type, address-of, and value of an instruction's operand. */
 143 struct operand {
 144         enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
 145         unsigned int bytes;
 146         unsigned long orig_val, *ptr;
 147         union {
 148                 unsigned long val;
 149                 char valptr[sizeof(unsigned long) + 2];
 150         };
 151 };
 152
 153 struct fetch_cache {
 154         u8 data[15];
 155         unsigned long start;
 156         unsigned long end;
 157 };
 158
 159 struct read_cache {
 160         u8 data[1024];
 161         unsigned long pos;
 162         unsigned long end;
 163 };
 164
 165 struct decode_cache {
 166         u8 twobyte;
 167         u8 b;
 168         u8 lock_prefix;
 169         u8 rep_prefix;
 170         u8 op_bytes;
 171         u8 ad_bytes;
 172         u8 rex_prefix;
 173         struct operand src;
 174         struct operand src2;
 175         struct operand dst;
 176         bool has_seg_override;
 177         u8 seg_override;
 178         unsigned int d;
 179         unsigned long regs[NR_VCPU_REGS];
 180         unsigned long eip;
 181         /* modrm */
 182         u8 modrm;
 183         u8 modrm_mod;
 184         u8 modrm_reg;
 185         u8 modrm_rm;
 186         u8 use_modrm_ea;
 187         bool rip_relative;
 188         unsigned long modrm_ea;
 189         void *modrm_ptr;
 190         unsigned long modrm_val;
 191         struct fetch_cache fetch;
 192         struct read_cache io_read;
 193         struct read_cache mem_read;
 194 };
 195
 196 struct x86_emulate_ctxt {
 197         /* Register state before/after emulation. */
 198         struct kvm_vcpu *vcpu;
 199
 200         unsigned long eflags;
 201         unsigned long eip; /* eip before instruction emulation */
 202         /* Emulated execution mode, represented by an X86EMUL_MODE value. */
 203         int mode;
 204         u32 cs_base;
 205
 206         /* interruptibility state, as a result of execution of STI or MOV SS */
 207         int interruptibility;
 208
 209         bool restart; /* restart string instruction after writeback */
 210         /* decode cache */
 211         struct decode_cache decode;
 212 };
 213
 214 /* Repeat String Operation Prefix */
 215 #define REPE_PREFIX     1
 216 #define REPNE_PREFIX    2
 217
 218 /* Execution mode, passed to the emulator. */
 219 #define X86EMUL_MODE_REAL     0 /* Real mode.             */
 220 #define X86EMUL_MODE_VM86     1 /* Virtual 8086 mode.     */
 221 #define X86EMUL_MODE_PROT16   2 /* 16-bit protected mode. */
 222 #define X86EMUL_MODE_PROT32   4 /* 32-bit protected mode. */
 223 #define X86EMUL_MODE_PROT64   8 /* 64-bit (long) mode.    */
 224
 225 /* Host execution mode. */
 226 #if defined(CONFIG_X86_32)
 227 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
 228 #elif defined(CONFIG_X86_64)
 229 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
 230 #endif
 231
 232 int x86_decode_insn(struct x86_emulate_ctxt *ctxt,
 233                     struct x86_emulate_ops *ops);
 234 int x86_emulate_insn(struct x86_emulate_ctxt *ctxt,
 235                      struct x86_emulate_ops *ops);
 236 int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
 237                          struct x86_emulate_ops *ops,
 238                          u16 tss_selector, int reason,
 239                          bool has_error_code, u32 error_code);
 240
 241 #endif /* _ASM_X86_KVM_X86_EMULATE_H */