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Diffstat (limited to 'drivers/kvm/x86_emulate.h')
| -rw-r--r-- | drivers/kvm/x86_emulate.h | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/drivers/kvm/x86_emulate.h b/drivers/kvm/x86_emulate.h new file mode 100644 index 0000000000000..658b58de30fc8 --- /dev/null +++ b/drivers/kvm/x86_emulate.h @@ -0,0 +1,185 @@ +/****************************************************************************** + * x86_emulate.h + * + * Generic x86 (32-bit and 64-bit) instruction decoder and emulator. + * + * Copyright (c) 2005 Keir Fraser + * + * From: xen-unstable 10676:af9809f51f81a3c43f276f00c81a52ef558afda4 + */ + +#ifndef __X86_EMULATE_H__ +#define __X86_EMULATE_H__ + +struct x86_emulate_ctxt; + +/* + * x86_emulate_ops: + * + * These operations represent the instruction emulator's interface to memory. + * There are two categories of operation: those that act on ordinary memory + * regions (*_std), and those that act on memory regions known to require + * special treatment or emulation (*_emulated). + * + * The emulator assumes that an instruction accesses only one 'emulated memory' + * location, that this location is the given linear faulting address (cr2), and + * that this is one of the instruction's data operands. Instruction fetches and + * stack operations are assumed never to access emulated memory. The emulator + * automatically deduces which operand of a string-move operation is accessing + * emulated memory, and assumes that the other operand accesses normal memory. + * + * NOTES: + * 1. The emulator isn't very smart about emulated vs. standard memory. + * 'Emulated memory' access addresses should be checked for sanity. + * 'Normal memory' accesses may fault, and the caller must arrange to + * detect and handle reentrancy into the emulator via recursive faults. + * Accesses may be unaligned and may cross page boundaries. + * 2. If the access fails (cannot emulate, or a standard access faults) then + * it is up to the memop to propagate the fault to the guest VM via + * some out-of-band mechanism, unknown to the emulator. The memop signals + * failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will + * then immediately bail. + * 3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only + * cmpxchg8b_emulated need support 8-byte accesses. + * 4. The emulator cannot handle 64-bit mode emulation on an x86/32 system. + */ +/* Access completed successfully: continue emulation as normal. */ +#define X86EMUL_CONTINUE 0 +/* Access is unhandleable: bail from emulation and return error to caller. */ +#define X86EMUL_UNHANDLEABLE 1 +/* Terminate emulation but return success to the caller. */ +#define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */ +#define X86EMUL_RETRY_INSTR 2 /* retry the instruction for some reason */ +#define X86EMUL_CMPXCHG_FAILED 2 /* cmpxchg did not see expected value */ +struct x86_emulate_ops { + /* + * read_std: Read bytes of standard (non-emulated/special) memory. + * Used for instruction fetch, stack operations, and others. + * @addr: [IN ] Linear address from which to read. + * @val: [OUT] Value read from memory, zero-extended to 'u_long'. + * @bytes: [IN ] Number of bytes to read from memory. + */ + int (*read_std)(unsigned long addr, + unsigned long *val, + unsigned int bytes, struct x86_emulate_ctxt * ctxt); + + /* + * write_std: Write bytes of standard (non-emulated/special) memory. + * Used for stack operations, and others. + * @addr: [IN ] Linear address to which to write. + * @val: [IN ] Value to write to memory (low-order bytes used as + * required). + * @bytes: [IN ] Number of bytes to write to memory. + */ + int (*write_std)(unsigned long addr, + unsigned long val, + unsigned int bytes, struct x86_emulate_ctxt * ctxt); + + /* + * read_emulated: Read bytes from emulated/special memory area. + * @addr: [IN ] Linear address from which to read. + * @val: [OUT] Value read from memory, zero-extended to 'u_long'. + * @bytes: [IN ] Number of bytes to read from memory. + */ + int (*read_emulated) (unsigned long addr, + unsigned long *val, + unsigned int bytes, + struct x86_emulate_ctxt * ctxt); + + /* + * write_emulated: Read bytes from emulated/special memory area. + * @addr: [IN ] Linear address to which to write. + * @val: [IN ] Value to write to memory (low-order bytes used as + * required). + * @bytes: [IN ] Number of bytes to write to memory. + */ + int (*write_emulated) (unsigned long addr, + unsigned long val, + unsigned int bytes, + struct x86_emulate_ctxt * ctxt); + + /* + * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an + * emulated/special memory area. + * @addr: [IN ] Linear address to access. + * @old: [IN ] Value expected to be current at @addr. + * @new: [IN ] Value to write to @addr. + * @bytes: [IN ] Number of bytes to access using CMPXCHG. + */ + int (*cmpxchg_emulated) (unsigned long addr, + unsigned long old, + unsigned long new, + unsigned int bytes, + struct x86_emulate_ctxt * ctxt); + + /* + * cmpxchg8b_emulated: Emulate an atomic (LOCKed) CMPXCHG8B operation on an + * emulated/special memory area. + * @addr: [IN ] Linear address to access. + * @old: [IN ] Value expected to be current at @addr. + * @new: [IN ] Value to write to @addr. + * NOTES: + * 1. This function is only ever called when emulating a real CMPXCHG8B. + * 2. This function is *never* called on x86/64 systems. + * 2. Not defining this function (i.e., specifying NULL) is equivalent + * to defining a function that always returns X86EMUL_UNHANDLEABLE. + */ + int (*cmpxchg8b_emulated) (unsigned long addr, + unsigned long old_lo, + unsigned long old_hi, + unsigned long new_lo, + unsigned long new_hi, + struct x86_emulate_ctxt * ctxt); +}; + +struct cpu_user_regs; + +struct x86_emulate_ctxt { + /* Register state before/after emulation. */ + struct kvm_vcpu *vcpu; + + /* Linear faulting address (if emulating a page-faulting instruction). */ + unsigned long eflags; + unsigned long cr2; + + /* Emulated execution mode, represented by an X86EMUL_MODE value. */ + int mode; + + unsigned long cs_base; + unsigned long ds_base; + unsigned long es_base; + unsigned long ss_base; + unsigned long gs_base; + unsigned long fs_base; +}; + +/* Execution mode, passed to the emulator. */ +#define X86EMUL_MODE_REAL 0 /* Real mode. */ +#define X86EMUL_MODE_PROT16 2 /* 16-bit protected mode. */ +#define X86EMUL_MODE_PROT32 4 /* 32-bit protected mode. */ +#define X86EMUL_MODE_PROT64 8 /* 64-bit (long) mode. */ + +/* Host execution mode. */ +#if defined(__i386__) +#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32 +#elif defined(__x86_64__) +#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64 +#endif + +/* + * x86_emulate_memop: Emulate an instruction that faulted attempting to + * read/write a 'special' memory area. + * Returns -1 on failure, 0 on success. + */ +int x86_emulate_memop(struct x86_emulate_ctxt *ctxt, + struct x86_emulate_ops *ops); + +/* + * Given the 'reg' portion of a ModRM byte, and a register block, return a + * pointer into the block that addresses the relevant register. + * @highbyte_regs specifies whether to decode AH,CH,DH,BH. + */ +void *decode_register(u8 modrm_reg, unsigned long *regs, + int highbyte_regs); + +#endif /* __X86_EMULATE_H__ */ |