1 /******************************************************************************
4 * Generic x86 (32-bit and 64-bit) instruction decoder and emulator.
6 * Copyright (c) 2005 Keir Fraser
8 * From: xen-unstable 10676:af9809f51f81a3c43f276f00c81a52ef558afda4
11 #ifndef _ASM_X86_KVM_X86_EMULATE_H
12 #define _ASM_X86_KVM_X86_EMULATE_H
14 struct x86_emulate_ctxt;
19 * These operations represent the instruction emulator's interface to memory.
20 * There are two categories of operation: those that act on ordinary memory
21 * regions (*_std), and those that act on memory regions known to require
22 * special treatment or emulation (*_emulated).
24 * The emulator assumes that an instruction accesses only one 'emulated memory'
25 * location, that this location is the given linear faulting address (cr2), and
26 * that this is one of the instruction's data operands. Instruction fetches and
27 * stack operations are assumed never to access emulated memory. The emulator
28 * automatically deduces which operand of a string-move operation is accessing
29 * emulated memory, and assumes that the other operand accesses normal memory.
32 * 1. The emulator isn't very smart about emulated vs. standard memory.
33 * 'Emulated memory' access addresses should be checked for sanity.
34 * 'Normal memory' accesses may fault, and the caller must arrange to
35 * detect and handle reentrancy into the emulator via recursive faults.
36 * Accesses may be unaligned and may cross page boundaries.
37 * 2. If the access fails (cannot emulate, or a standard access faults) then
38 * it is up to the memop to propagate the fault to the guest VM via
39 * some out-of-band mechanism, unknown to the emulator. The memop signals
40 * failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
41 * then immediately bail.
42 * 3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
43 * cmpxchg8b_emulated need support 8-byte accesses.
44 * 4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
46 /* Access completed successfully: continue emulation as normal. */
47 #define X86EMUL_CONTINUE 0
48 /* Access is unhandleable: bail from emulation and return error to caller. */
49 #define X86EMUL_UNHANDLEABLE 1
50 /* Terminate emulation but return success to the caller. */
51 #define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */
52 #define X86EMUL_RETRY_INSTR 2 /* retry the instruction for some reason */
53 #define X86EMUL_CMPXCHG_FAILED 2 /* cmpxchg did not see expected value */
54 struct x86_emulate_ops {
56 * read_std: Read bytes of standard (non-emulated/special) memory.
57 * Used for descriptor reading.
58 * @addr: [IN ] Linear address from which to read.
59 * @val: [OUT] Value read from memory, zero-extended to 'u_long'.
60 * @bytes: [IN ] Number of bytes to read from memory.
62 int (*read_std)(unsigned long addr, void *val,
63 unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
66 * write_std: Write bytes of standard (non-emulated/special) memory.
67 * Used for descriptor writing.
68 * @addr: [IN ] Linear address to which to write.
69 * @val: [OUT] Value write to memory, zero-extended to 'u_long'.
70 * @bytes: [IN ] Number of bytes to write to memory.
72 int (*write_std)(unsigned long addr, void *val,
73 unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
75 * fetch: Read bytes of standard (non-emulated/special) memory.
76 * Used for instruction fetch.
77 * @addr: [IN ] Linear address from which to read.
78 * @val: [OUT] Value read from memory, zero-extended to 'u_long'.
79 * @bytes: [IN ] Number of bytes to read from memory.
81 int (*fetch)(unsigned long addr, void *val,
82 unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
85 * read_emulated: Read bytes from emulated/special memory area.
86 * @addr: [IN ] Linear address from which to read.
87 * @val: [OUT] Value read from memory, zero-extended to 'u_long'.
88 * @bytes: [IN ] Number of bytes to read from memory.
90 int (*read_emulated)(unsigned long addr,
93 struct kvm_vcpu *vcpu);
96 * write_emulated: Write bytes to emulated/special memory area.
97 * @addr: [IN ] Linear address to which to write.
98 * @val: [IN ] Value to write to memory (low-order bytes used as
100 * @bytes: [IN ] Number of bytes to write to memory.
102 int (*write_emulated)(unsigned long addr,
105 struct kvm_vcpu *vcpu);
108 * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
109 * emulated/special memory area.
110 * @addr: [IN ] Linear address to access.
111 * @old: [IN ] Value expected to be current at @addr.
112 * @new: [IN ] Value to write to @addr.
113 * @bytes: [IN ] Number of bytes to access using CMPXCHG.
115 int (*cmpxchg_emulated)(unsigned long addr,
119 struct kvm_vcpu *vcpu);
120 bool (*get_cached_descriptor)(struct desc_struct *desc,
121 int seg, struct kvm_vcpu *vcpu);
122 void (*set_cached_descriptor)(struct desc_struct *desc,
123 int seg, struct kvm_vcpu *vcpu);
124 u16 (*get_segment_selector)(int seg, struct kvm_vcpu *vcpu);
125 void (*set_segment_selector)(u16 sel, int seg, struct kvm_vcpu *vcpu);
126 void (*get_gdt)(struct desc_ptr *dt, struct kvm_vcpu *vcpu);
127 ulong (*get_cr)(int cr, struct kvm_vcpu *vcpu);
128 void (*set_cr)(int cr, ulong val, struct kvm_vcpu *vcpu);
129 int (*cpl)(struct kvm_vcpu *vcpu);
132 /* Type, address-of, and value of an instruction's operand. */
134 enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
136 unsigned long val, orig_val, *ptr;
145 struct decode_cache {
156 bool has_seg_override;
159 unsigned long regs[NR_VCPU_REGS];
168 unsigned long modrm_ea;
170 unsigned long modrm_val;
171 struct fetch_cache fetch;
174 struct x86_emulate_ctxt {
175 /* Register state before/after emulation. */
176 struct kvm_vcpu *vcpu;
178 unsigned long eflags;
179 unsigned long eip; /* eip before instruction emulation */
180 /* Emulated execution mode, represented by an X86EMUL_MODE value. */
184 /* interruptibility state, as a result of execution of STI or MOV SS */
185 int interruptibility;
188 struct decode_cache decode;
191 /* Repeat String Operation Prefix */
192 #define REPE_PREFIX 1
193 #define REPNE_PREFIX 2
195 /* Execution mode, passed to the emulator. */
196 #define X86EMUL_MODE_REAL 0 /* Real mode. */
197 #define X86EMUL_MODE_VM86 1 /* Virtual 8086 mode. */
198 #define X86EMUL_MODE_PROT16 2 /* 16-bit protected mode. */
199 #define X86EMUL_MODE_PROT32 4 /* 32-bit protected mode. */
200 #define X86EMUL_MODE_PROT64 8 /* 64-bit (long) mode. */
202 /* Host execution mode. */
203 #if defined(CONFIG_X86_32)
204 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
205 #elif defined(CONFIG_X86_64)
206 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
209 int x86_decode_insn(struct x86_emulate_ctxt *ctxt,
210 struct x86_emulate_ops *ops);
211 int x86_emulate_insn(struct x86_emulate_ctxt *ctxt,
212 struct x86_emulate_ops *ops);
214 #endif /* _ASM_X86_KVM_X86_EMULATE_H */