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 struct x86_exception {
  19         u8 vector;
  20         bool error_code_valid;
  21         u16 error_code;
  22         bool nested_page_fault;
  23         u64 address; /* cr2 or nested page fault gpa */
  24 };
  25
  26 /*
  27  * x86_emulate_ops:
  28  *
  29  * These operations represent the instruction emulator's interface to memory.
  30  * There are two categories of operation: those that act on ordinary memory
  31  * regions (*_std), and those that act on memory regions known to require
  32  * special treatment or emulation (*_emulated).
  33  *
  34  * The emulator assumes that an instruction accesses only one 'emulated memory'
  35  * location, that this location is the given linear faulting address (cr2), and
  36  * that this is one of the instruction's data operands. Instruction fetches and
  37  * stack operations are assumed never to access emulated memory. The emulator
  38  * automatically deduces which operand of a string-move operation is accessing
  39  * emulated memory, and assumes that the other operand accesses normal memory.
  40  *
  41  * NOTES:
  42  *  1. The emulator isn't very smart about emulated vs. standard memory.
  43  *     'Emulated memory' access addresses should be checked for sanity.
  44  *     'Normal memory' accesses may fault, and the caller must arrange to
  45  *     detect and handle reentrancy into the emulator via recursive faults.
  46  *     Accesses may be unaligned and may cross page boundaries.
  47  *  2. If the access fails (cannot emulate, or a standard access faults) then
  48  *     it is up to the memop to propagate the fault to the guest VM via
  49  *     some out-of-band mechanism, unknown to the emulator. The memop signals
  50  *     failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
  51  *     then immediately bail.
  52  *  3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
  53  *     cmpxchg8b_emulated need support 8-byte accesses.
  54  *  4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
  55  */
  56 /* Access completed successfully: continue emulation as normal. */
  57 #define X86EMUL_CONTINUE        0
  58 /* Access is unhandleable: bail from emulation and return error to caller. */
  59 #define X86EMUL_UNHANDLEABLE    1
  60 /* Terminate emulation but return success to the caller. */
  61 #define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */
  62 #define X86EMUL_RETRY_INSTR     3 /* retry the instruction for some reason */
  63 #define X86EMUL_CMPXCHG_FAILED  4 /* cmpxchg did not see expected value */
  64 #define X86EMUL_IO_NEEDED       5 /* IO is needed to complete emulation */
  65
  66 struct x86_emulate_ops {
  67         /*
  68          * read_std: Read bytes of standard (non-emulated/special) memory.
  69          *           Used for descriptor reading.
  70          *  @addr:  [IN ] Linear address from which to read.
  71          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  72          *  @bytes: [IN ] Number of bytes to read from memory.
  73          */
  74         int (*read_std)(unsigned long addr, void *val,
  75                         unsigned int bytes, struct kvm_vcpu *vcpu,
  76                         struct x86_exception *fault);
  77
  78         /*
  79          * write_std: Write bytes of standard (non-emulated/special) memory.
  80          *            Used for descriptor writing.
  81          *  @addr:  [IN ] Linear address to which to write.
  82          *  @val:   [OUT] Value write to memory, zero-extended to 'u_long'.
  83          *  @bytes: [IN ] Number of bytes to write to memory.
  84          */
  85         int (*write_std)(unsigned long addr, void *val,
  86                          unsigned int bytes, struct kvm_vcpu *vcpu,
  87                          struct x86_exception *fault);
  88         /*
  89          * fetch: Read bytes of standard (non-emulated/special) memory.
  90          *        Used for instruction fetch.
  91          *  @addr:  [IN ] Linear address from which to read.
  92          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
  93          *  @bytes: [IN ] Number of bytes to read from memory.
  94          */
  95         int (*fetch)(unsigned long addr, void *val,
  96                      unsigned int bytes, struct kvm_vcpu *vcpu,
  97                      struct x86_exception *fault);
  98
  99         /*
 100          * read_emulated: Read bytes from emulated/special memory area.
 101          *  @addr:  [IN ] Linear address from which to read.
 102          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
 103          *  @bytes: [IN ] Number of bytes to read from memory.
 104          */
 105         int (*read_emulated)(unsigned long addr,
 106                              void *val,
 107                              unsigned int bytes,
 108                              struct x86_exception *fault,
 109                              struct kvm_vcpu *vcpu);
 110
 111         /*
 112          * write_emulated: Write bytes to emulated/special memory area.
 113          *  @addr:  [IN ] Linear address to which to write.
 114          *  @val:   [IN ] Value to write to memory (low-order bytes used as
 115          *                required).
 116          *  @bytes: [IN ] Number of bytes to write to memory.
 117          */
 118         int (*write_emulated)(unsigned long addr,
 119                               const void *val,
 120                               unsigned int bytes,
 121                               struct x86_exception *fault,
 122                               struct kvm_vcpu *vcpu);
 123
 124         /*
 125          * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
 126          *                   emulated/special memory area.
 127          *  @addr:  [IN ] Linear address to access.
 128          *  @old:   [IN ] Value expected to be current at @addr.
 129          *  @new:   [IN ] Value to write to @addr.
 130          *  @bytes: [IN ] Number of bytes to access using CMPXCHG.
 131          */
 132         int (*cmpxchg_emulated)(unsigned long addr,
 133                                 const void *old,
 134                                 const void *new,
 135                                 unsigned int bytes,
 136                                 struct x86_exception *fault,
 137                                 struct kvm_vcpu *vcpu);
 138
 139         int (*pio_in_emulated)(int size, unsigned short port, void *val,
 140                                unsigned int count, struct kvm_vcpu *vcpu);
 141
 142         int (*pio_out_emulated)(int size, unsigned short port, const void *val,
 143                                 unsigned int count, struct kvm_vcpu *vcpu);
 144
 145         bool (*get_cached_descriptor)(struct desc_struct *desc, u32 *base3,
 146                                       int seg, struct kvm_vcpu *vcpu);
 147         void (*set_cached_descriptor)(struct desc_struct *desc, u32 base3,
 148                                       int seg, struct kvm_vcpu *vcpu);
 149         u16 (*get_segment_selector)(int seg, struct kvm_vcpu *vcpu);
 150         void (*set_segment_selector)(u16 sel, int seg, struct kvm_vcpu *vcpu);
 151         unsigned long (*get_cached_segment_base)(int seg, struct kvm_vcpu *vcpu);
 152         void (*get_gdt)(struct desc_ptr *dt, struct kvm_vcpu *vcpu);
 153         void (*get_idt)(struct desc_ptr *dt, struct kvm_vcpu *vcpu);
 154         ulong (*get_cr)(int cr, struct kvm_vcpu *vcpu);
 155         int (*set_cr)(int cr, ulong val, struct kvm_vcpu *vcpu);
 156         int (*cpl)(struct kvm_vcpu *vcpu);
 157         int (*get_dr)(int dr, unsigned long *dest, struct kvm_vcpu *vcpu);
 158         int (*set_dr)(int dr, unsigned long value, struct kvm_vcpu *vcpu);
 159         int (*set_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
 160         int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
 161 };
 162
 163 /* Type, address-of, and value of an instruction's operand. */
 164 struct operand {
 165         enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
 166         unsigned int bytes;
 167         union {
 168                 unsigned long orig_val;
 169                 u64 orig_val64;
 170         };
 171         union {
 172                 unsigned long *reg;
 173                 struct segmented_address {
 174                         ulong ea;
 175                         unsigned seg;
 176                 } mem;
 177         } addr;
 178         union {
 179                 unsigned long val;
 180                 u64 val64;
 181                 char valptr[sizeof(unsigned long) + 2];
 182         };
 183 };
 184
 185 struct fetch_cache {
 186         u8 data[15];
 187         unsigned long start;
 188         unsigned long end;
 189 };
 190
 191 struct read_cache {
 192         u8 data[1024];
 193         unsigned long pos;
 194         unsigned long end;
 195 };
 196
 197 struct decode_cache {
 198         u8 twobyte;
 199         u8 b;
 200         u8 lock_prefix;
 201         u8 rep_prefix;
 202         u8 op_bytes;
 203         u8 ad_bytes;
 204         u8 rex_prefix;
 205         struct operand src;
 206         struct operand src2;
 207         struct operand dst;
 208         bool has_seg_override;
 209         u8 seg_override;
 210         unsigned int d;
 211         int (*execute)(struct x86_emulate_ctxt *ctxt);
 212         unsigned long regs[NR_VCPU_REGS];
 213         unsigned long eip;
 214         /* modrm */
 215         u8 modrm;
 216         u8 modrm_mod;
 217         u8 modrm_reg;
 218         u8 modrm_rm;
 219         u8 modrm_seg;
 220         bool rip_relative;
 221         struct fetch_cache fetch;
 222         struct read_cache io_read;
 223         struct read_cache mem_read;
 224 };
 225
 226 struct x86_emulate_ctxt {
 227         struct x86_emulate_ops *ops;
 228
 229         /* Register state before/after emulation. */
 230         struct kvm_vcpu *vcpu;
 231
 232         unsigned long eflags;
 233         unsigned long eip; /* eip before instruction emulation */
 234         /* Emulated execution mode, represented by an X86EMUL_MODE value. */
 235         int mode;
 236         u32 cs_base;
 237
 238         /* interruptibility state, as a result of execution of STI or MOV SS */
 239         int interruptibility;
 240
 241         bool perm_ok; /* do not check permissions if true */
 242         bool only_vendor_specific_insn;
 243
 244         bool have_exception;
 245         struct x86_exception exception;
 246
 247         /* decode cache */
 248         struct decode_cache decode;
 249 };
 250
 251 /* Repeat String Operation Prefix */
 252 #define REPE_PREFIX     0xf3
 253 #define REPNE_PREFIX    0xf2
 254
 255 /* Execution mode, passed to the emulator. */
 256 #define X86EMUL_MODE_REAL     0 /* Real mode.             */
 257 #define X86EMUL_MODE_VM86     1 /* Virtual 8086 mode.     */
 258 #define X86EMUL_MODE_PROT16   2 /* 16-bit protected mode. */
 259 #define X86EMUL_MODE_PROT32   4 /* 32-bit protected mode. */
 260 #define X86EMUL_MODE_PROT64   8 /* 64-bit (long) mode.    */
 261
 262 /* Host execution mode. */
 263 #if defined(CONFIG_X86_32)
 264 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
 265 #elif defined(CONFIG_X86_64)
 266 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
 267 #endif
 268
 269 int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len);
 270 #define EMULATION_FAILED -1
 271 #define EMULATION_OK 0
 272 #define EMULATION_RESTART 1
 273 int x86_emulate_insn(struct x86_emulate_ctxt *ctxt);
 274 int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
 275                          u16 tss_selector, int reason,
 276                          bool has_error_code, u32 error_code);
 277 int emulate_int_real(struct x86_emulate_ctxt *ctxt,
 278                      struct x86_emulate_ops *ops, int irq);
 279 #endif /* _ASM_X86_KVM_X86_EMULATE_H */