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 enum x86_intercept;
  18 enum x86_intercept_stage;
  19
  20 struct x86_exception {
  21         u8 vector;
  22         bool error_code_valid;
  23         u16 error_code;
  24         bool nested_page_fault;
  25         u64 address; /* cr2 or nested page fault gpa */
  26 };
  27
  28 /*
  29  * This struct is used to carry enough information from the instruction
  30  * decoder to main KVM so that a decision can be made whether the
  31  * instruction needs to be intercepted or not.
  32  */
  33 struct x86_instruction_info {
  34         u8  intercept;          /* which intercept                      */
  35         u8  rep_prefix;         /* rep prefix?                          */
  36         u8  modrm_mod;          /* mod part of modrm                    */
  37         u8  modrm_reg;          /* index of register used               */
  38         u8  modrm_rm;           /* rm part of modrm                     */
  39         u64 src_val;            /* value of source operand              */
  40         u8  src_bytes;          /* size of source operand               */
  41         u8  dst_bytes;          /* size of destination operand          */
  42         u8  ad_bytes;           /* size of src/dst address              */
  43         u64 next_rip;           /* rip following the instruction        */
  44 };
  45
  46 /*
  47  * x86_emulate_ops:
  48  *
  49  * These operations represent the instruction emulator's interface to memory.
  50  * There are two categories of operation: those that act on ordinary memory
  51  * regions (*_std), and those that act on memory regions known to require
  52  * special treatment or emulation (*_emulated).
  53  *
  54  * The emulator assumes that an instruction accesses only one 'emulated memory'
  55  * location, that this location is the given linear faulting address (cr2), and
  56  * that this is one of the instruction's data operands. Instruction fetches and
  57  * stack operations are assumed never to access emulated memory. The emulator
  58  * automatically deduces which operand of a string-move operation is accessing
  59  * emulated memory, and assumes that the other operand accesses normal memory.
  60  *
  61  * NOTES:
  62  *  1. The emulator isn't very smart about emulated vs. standard memory.
  63  *     'Emulated memory' access addresses should be checked for sanity.
  64  *     'Normal memory' accesses may fault, and the caller must arrange to
  65  *     detect and handle reentrancy into the emulator via recursive faults.
  66  *     Accesses may be unaligned and may cross page boundaries.
  67  *  2. If the access fails (cannot emulate, or a standard access faults) then
  68  *     it is up to the memop to propagate the fault to the guest VM via
  69  *     some out-of-band mechanism, unknown to the emulator. The memop signals
  70  *     failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
  71  *     then immediately bail.
  72  *  3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
  73  *     cmpxchg8b_emulated need support 8-byte accesses.
  74  *  4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
  75  */
  76 /* Access completed successfully: continue emulation as normal. */
  77 #define X86EMUL_CONTINUE        0
  78 /* Access is unhandleable: bail from emulation and return error to caller. */
  79 #define X86EMUL_UNHANDLEABLE    1
  80 /* Terminate emulation but return success to the caller. */
  81 #define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */
  82 #define X86EMUL_RETRY_INSTR     3 /* retry the instruction for some reason */
  83 #define X86EMUL_CMPXCHG_FAILED  4 /* cmpxchg did not see expected value */
  84 #define X86EMUL_IO_NEEDED       5 /* IO is needed to complete emulation */
  85 #define X86EMUL_INTERCEPTED     6 /* Intercepted by nested VMCB/VMCS */
  86
  87 struct x86_emulate_ops {
  88         /*
  89          * read_std: Read bytes of standard (non-emulated/special) memory.
  90          *           Used for descriptor reading.
  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 (*read_std)(struct x86_emulate_ctxt *ctxt,
  96                         unsigned long addr, void *val,
  97                         unsigned int bytes,
  98                         struct x86_exception *fault);
  99
 100         /*
 101          * write_std: Write bytes of standard (non-emulated/special) memory.
 102          *            Used for descriptor writing.
 103          *  @addr:  [IN ] Linear address to which to write.
 104          *  @val:   [OUT] Value write to memory, zero-extended to 'u_long'.
 105          *  @bytes: [IN ] Number of bytes to write to memory.
 106          */
 107         int (*write_std)(struct x86_emulate_ctxt *ctxt,
 108                          unsigned long addr, void *val, unsigned int bytes,
 109                          struct x86_exception *fault);
 110         /*
 111          * fetch: Read bytes of standard (non-emulated/special) memory.
 112          *        Used for instruction fetch.
 113          *  @addr:  [IN ] Linear address from which to read.
 114          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
 115          *  @bytes: [IN ] Number of bytes to read from memory.
 116          */
 117         int (*fetch)(struct x86_emulate_ctxt *ctxt,
 118                      unsigned long addr, void *val, unsigned int bytes,
 119                      struct x86_exception *fault);
 120
 121         /*
 122          * read_emulated: Read bytes from emulated/special memory area.
 123          *  @addr:  [IN ] Linear address from which to read.
 124          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
 125          *  @bytes: [IN ] Number of bytes to read from memory.
 126          */
 127         int (*read_emulated)(struct x86_emulate_ctxt *ctxt,
 128                              unsigned long addr, void *val, unsigned int bytes,
 129                              struct x86_exception *fault);
 130
 131         /*
 132          * write_emulated: Write bytes to emulated/special memory area.
 133          *  @addr:  [IN ] Linear address to which to write.
 134          *  @val:   [IN ] Value to write to memory (low-order bytes used as
 135          *                required).
 136          *  @bytes: [IN ] Number of bytes to write to memory.
 137          */
 138         int (*write_emulated)(struct x86_emulate_ctxt *ctxt,
 139                               unsigned long addr, const void *val,
 140                               unsigned int bytes,
 141                               struct x86_exception *fault);
 142
 143         /*
 144          * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
 145          *                   emulated/special memory area.
 146          *  @addr:  [IN ] Linear address to access.
 147          *  @old:   [IN ] Value expected to be current at @addr.
 148          *  @new:   [IN ] Value to write to @addr.
 149          *  @bytes: [IN ] Number of bytes to access using CMPXCHG.
 150          */
 151         int (*cmpxchg_emulated)(struct x86_emulate_ctxt *ctxt,
 152                                 unsigned long addr,
 153                                 const void *old,
 154                                 const void *new,
 155                                 unsigned int bytes,
 156                                 struct x86_exception *fault);
 157
 158         int (*pio_in_emulated)(struct x86_emulate_ctxt *ctxt,
 159                                int size, unsigned short port, void *val,
 160                                unsigned int count);
 161
 162         int (*pio_out_emulated)(struct x86_emulate_ctxt *ctxt,
 163                                 int size, unsigned short port, const void *val,
 164                                 unsigned int count);
 165
 166         bool (*get_cached_descriptor)(struct x86_emulate_ctxt *ctxt,
 167                                       struct desc_struct *desc, u32 *base3,
 168                                       int seg);
 169         void (*set_cached_descriptor)(struct x86_emulate_ctxt *ctxt,
 170                                       struct desc_struct *desc, u32 base3,
 171                                       int seg);
 172         u16 (*get_segment_selector)(struct x86_emulate_ctxt *ctxt, int seg);
 173         void (*set_segment_selector)(struct x86_emulate_ctxt *ctxt,
 174                                      u16 sel, int seg);
 175         unsigned long (*get_cached_segment_base)(struct x86_emulate_ctxt *ctxt,
 176                                                  int seg);
 177         void (*get_gdt)(struct x86_emulate_ctxt *ctxt, struct desc_ptr *dt);
 178         void (*get_idt)(struct x86_emulate_ctxt *ctxt, struct desc_ptr *dt);
 179         ulong (*get_cr)(struct x86_emulate_ctxt *ctxt, int cr);
 180         int (*set_cr)(struct x86_emulate_ctxt *ctxt, int cr, ulong val);
 181         int (*cpl)(struct x86_emulate_ctxt *ctxt);
 182         int (*get_dr)(struct x86_emulate_ctxt *ctxt, int dr, ulong *dest);
 183         int (*set_dr)(struct x86_emulate_ctxt *ctxt, int dr, ulong value);
 184         int (*set_msr)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 data);
 185         int (*get_msr)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 *pdata);
 186         void (*get_fpu)(struct x86_emulate_ctxt *ctxt); /* disables preempt */
 187         void (*put_fpu)(struct x86_emulate_ctxt *ctxt); /* reenables preempt */
 188         int (*intercept)(struct x86_emulate_ctxt *ctxt,
 189                          struct x86_instruction_info *info,
 190                          enum x86_intercept_stage stage);
 191 };
 192
 193 typedef u32 __attribute__((vector_size(16))) sse128_t;
 194
 195 /* Type, address-of, and value of an instruction's operand. */
 196 struct operand {
 197         enum { OP_REG, OP_MEM, OP_IMM, OP_XMM, OP_NONE } type;
 198         unsigned int bytes;
 199         union {
 200                 unsigned long orig_val;
 201                 u64 orig_val64;
 202         };
 203         union {
 204                 unsigned long *reg;
 205                 struct segmented_address {
 206                         ulong ea;
 207                         unsigned seg;
 208                 } mem;
 209                 unsigned xmm;
 210         } addr;
 211         union {
 212                 unsigned long val;
 213                 u64 val64;
 214                 char valptr[sizeof(unsigned long) + 2];
 215                 sse128_t vec_val;
 216         };
 217 };
 218
 219 struct fetch_cache {
 220         u8 data[15];
 221         unsigned long start;
 222         unsigned long end;
 223 };
 224
 225 struct read_cache {
 226         u8 data[1024];
 227         unsigned long pos;
 228         unsigned long end;
 229 };
 230
 231 struct decode_cache {
 232         u8 twobyte;
 233         u8 b;
 234         u8 intercept;
 235         u8 lock_prefix;
 236         u8 rep_prefix;
 237         u8 op_bytes;
 238         u8 ad_bytes;
 239         u8 rex_prefix;
 240         struct operand src;
 241         struct operand src2;
 242         struct operand dst;
 243         bool has_seg_override;
 244         u8 seg_override;
 245         unsigned int d;
 246         int (*execute)(struct x86_emulate_ctxt *ctxt);
 247         int (*check_perm)(struct x86_emulate_ctxt *ctxt);
 248         unsigned long regs[NR_VCPU_REGS];
 249         unsigned long eip;
 250         /* modrm */
 251         u8 modrm;
 252         u8 modrm_mod;
 253         u8 modrm_reg;
 254         u8 modrm_rm;
 255         u8 modrm_seg;
 256         bool rip_relative;
 257         struct fetch_cache fetch;
 258         struct read_cache io_read;
 259         struct read_cache mem_read;
 260 };
 261
 262 struct x86_emulate_ctxt {
 263         struct x86_emulate_ops *ops;
 264
 265         /* Register state before/after emulation. */
 266         struct kvm_vcpu *vcpu;
 267
 268         unsigned long eflags;
 269         unsigned long eip; /* eip before instruction emulation */
 270         /* Emulated execution mode, represented by an X86EMUL_MODE value. */
 271         int mode;
 272
 273         /* interruptibility state, as a result of execution of STI or MOV SS */
 274         int interruptibility;
 275
 276         bool guest_mode; /* guest running a nested guest */
 277         bool perm_ok; /* do not check permissions if true */
 278         bool only_vendor_specific_insn;
 279
 280         bool have_exception;
 281         struct x86_exception exception;
 282
 283         /* decode cache */
 284         struct decode_cache decode;
 285 };
 286
 287 /* Repeat String Operation Prefix */
 288 #define REPE_PREFIX     0xf3
 289 #define REPNE_PREFIX    0xf2
 290
 291 /* Execution mode, passed to the emulator. */
 292 #define X86EMUL_MODE_REAL     0 /* Real mode.             */
 293 #define X86EMUL_MODE_VM86     1 /* Virtual 8086 mode.     */
 294 #define X86EMUL_MODE_PROT16   2 /* 16-bit protected mode. */
 295 #define X86EMUL_MODE_PROT32   4 /* 32-bit protected mode. */
 296 #define X86EMUL_MODE_PROT64   8 /* 64-bit (long) mode.    */
 297
 298 /* any protected mode   */
 299 #define X86EMUL_MODE_PROT     (X86EMUL_MODE_PROT16|X86EMUL_MODE_PROT32| \
 300                                X86EMUL_MODE_PROT64)
 301
 302 enum x86_intercept_stage {
 303         X86_ICPT_PRE_EXCEPT,
 304         X86_ICPT_POST_EXCEPT,
 305         X86_ICPT_POST_MEMACCESS,
 306 };
 307
 308 enum x86_intercept {
 309         x86_intercept_none,
 310         x86_intercept_cr_read,
 311         x86_intercept_cr_write,
 312         x86_intercept_clts,
 313         x86_intercept_lmsw,
 314         x86_intercept_smsw,
 315         x86_intercept_dr_read,
 316         x86_intercept_dr_write,
 317         x86_intercept_lidt,
 318         x86_intercept_sidt,
 319         x86_intercept_lgdt,
 320         x86_intercept_sgdt,
 321         x86_intercept_lldt,
 322         x86_intercept_sldt,
 323         x86_intercept_ltr,
 324         x86_intercept_str,
 325         x86_intercept_rdtsc,
 326         x86_intercept_rdpmc,
 327         x86_intercept_pushf,
 328         x86_intercept_popf,
 329         x86_intercept_cpuid,
 330         x86_intercept_rsm,
 331         x86_intercept_iret,
 332         x86_intercept_intn,
 333         x86_intercept_invd,
 334         x86_intercept_pause,
 335         x86_intercept_hlt,
 336         x86_intercept_invlpg,
 337         x86_intercept_invlpga,
 338         x86_intercept_vmrun,
 339         x86_intercept_vmload,
 340         x86_intercept_vmsave,
 341         x86_intercept_vmmcall,
 342         x86_intercept_stgi,
 343         x86_intercept_clgi,
 344         x86_intercept_skinit,
 345         x86_intercept_rdtscp,
 346         x86_intercept_icebp,
 347         x86_intercept_wbinvd,
 348         x86_intercept_monitor,
 349         x86_intercept_mwait,
 350         x86_intercept_rdmsr,
 351         x86_intercept_wrmsr,
 352         x86_intercept_in,
 353         x86_intercept_ins,
 354         x86_intercept_out,
 355         x86_intercept_outs,
 356
 357         nr_x86_intercepts
 358 };
 359
 360 /* Host execution mode. */
 361 #if defined(CONFIG_X86_32)
 362 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
 363 #elif defined(CONFIG_X86_64)
 364 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
 365 #endif
 366
 367 int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len);
 368 #define EMULATION_FAILED -1
 369 #define EMULATION_OK 0
 370 #define EMULATION_RESTART 1
 371 #define EMULATION_INTERCEPTED 2
 372 int x86_emulate_insn(struct x86_emulate_ctxt *ctxt);
 373 int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
 374                          u16 tss_selector, int reason,
 375                          bool has_error_code, u32 error_code);
 376 int emulate_int_real(struct x86_emulate_ctxt *ctxt,
 377                      struct x86_emulate_ops *ops, int irq);
 378 #endif /* _ASM_X86_KVM_X86_EMULATE_H */