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