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KVM: x86 emulator: disable writeback when decode dest operand 

This patch change to disable writeback when decode dest
operand if the dest type is ImplicitOps or not specified.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Wei Yongjun 2010-08-04 15:38:18 +08:00 committed by Avi Kivity
parent 06cb704611
commit 36089fed70
1 changed files with 6 additions and 17 deletions
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23
arch/x86/kvm/emulate.c
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@ -2627,9 +2627,6 @@ done_prefixes:
/* Decode and fetch the destination operand: register or memory. */
switch (c->d & DstMask) {
case ImplicitOps:
/* Special instructions do their own operand decoding. */
return 0;
case DstReg:
decode_register_operand(&c->dst, c,
c->twobyte && (c->b == 0xb6 || c->b == 0xb7));
@ -2664,6 +2661,11 @@ done_prefixes:
c->regs[VCPU_REGS_RDI]);
c->dst.val = 0;
break;
case ImplicitOps:
/* Special instructions do their own operand decoding. */
default:
c->dst.type = OP_NONE; /* Disable writeback. */
return 0;
}
done:
@ -3115,7 +3117,6 @@ special_insn:
case 0xf5: /* cmc */
/* complement carry flag from eflags reg */
ctxt->eflags ^= EFLG_CF;
c->dst.type = OP_NONE; /* Disable writeback. */
break;
case 0xf6 ... 0xf7: /* Grp3 */
if (!emulate_grp3(ctxt, ops))
@ -3123,16 +3124,13 @@ special_insn:
break;
case 0xf8: /* clc */
ctxt->eflags &= ~EFLG_CF;
c->dst.type = OP_NONE; /* Disable writeback. */
break;
case 0xfa: /* cli */
if (emulator_bad_iopl(ctxt, ops)) {
emulate_gp(ctxt, 0);
goto done;
} else {
} else
ctxt->eflags &= ~X86_EFLAGS_IF;
c->dst.type = OP_NONE; /* Disable writeback. */
}
break;
case 0xfb: /* sti */
if (emulator_bad_iopl(ctxt, ops)) {
@ -3141,16 +3139,13 @@ special_insn:
} else {
ctxt->interruptibility = KVM_X86_SHADOW_INT_STI;
ctxt->eflags |= X86_EFLAGS_IF;
c->dst.type = OP_NONE; /* Disable writeback. */
}
break;
case 0xfc: /* cld */
ctxt->eflags &= ~EFLG_DF;
c->dst.type = OP_NONE; /* Disable writeback. */
break;
case 0xfd: /* std */
ctxt->eflags |= EFLG_DF;
c->dst.type = OP_NONE; /* Disable writeback. */
break;
case 0xfe: /* Grp4 */
grp45:
@ -3287,16 +3282,13 @@ twobyte_insn:
break;
case 0x06:
emulate_clts(ctxt->vcpu);
c->dst.type = OP_NONE;
break;
case 0x09: /* wbinvd */
kvm_emulate_wbinvd(ctxt->vcpu);
c->dst.type = OP_NONE;
break;
case 0x08: /* invd */
case 0x0d: /* GrpP (prefetch) */
case 0x18: /* Grp16 (prefetch/nop) */
c->dst.type = OP_NONE;
break;
case 0x20: /* mov cr, reg */
switch (c->modrm_reg) {
@ -3349,7 +3341,6 @@ twobyte_insn:
goto done;
}
rc = X86EMUL_CONTINUE;
c->dst.type = OP_NONE;
break;
case 0x32:
/* rdmsr */
@ -3361,7 +3352,6 @@ twobyte_insn:
c->regs[VCPU_REGS_RDX] = msr_data >> 32;
}
rc = X86EMUL_CONTINUE;
c->dst.type = OP_NONE;
break;
case 0x34: /* sysenter */
rc = emulate_sysenter(ctxt, ops);
@ -3385,7 +3375,6 @@ twobyte_insn:
case 0x80 ... 0x8f: /* jnz rel, etc*/
if (test_cc(c->b, ctxt->eflags))
jmp_rel(c, c->src.val);
c->dst.type = OP_NONE;
break;
case 0xa0: /* push fs */
emulate_push_sreg(ctxt, ops, VCPU_SREG_FS);