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KVM: x86 emulator: add decoding of CMPXCHG8B dst operand

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Decode CMPXCHG8B destination operand in decoding stage. Fixes regression
introduced by "If LOCK prefix is used dest arg should be memory" commit.
This commit relies on dst operand be decoded at the beginning of an
instruction emulation.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Gleb Natapov 2010-03-21 13:08:21 +02:00 committed by Avi Kivity
parent 482ac18ae2
commit 6550e1f165
1 changed files with 10 additions and 14 deletions
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24
arch/x86/kvm/emulate.c
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@ -52,6 +52,7 @@
#define DstMem (3<<1) /* Memory operand. */
#define DstAcc (4<<1) /* Destination Accumulator */
#define DstDI (5<<1) /* Destination is in ES:(E)DI */
#define DstMem64 (6<<1) /* 64bit memory operand */
#define DstMask (7<<1)
/* Source operand type. */
#define SrcNone (0<<4) /* No source operand. */
@ -360,7 +361,7 @@ static u32 group_table[] = {
DstMem | SrcImmByte | ModRM, DstMem | SrcImmByte | ModRM | Lock,
DstMem | SrcImmByte | ModRM | Lock, DstMem | SrcImmByte | ModRM | Lock,
[Group9*8] =
0, ImplicitOps | ModRM | Lock, 0, 0, 0, 0, 0, 0,
0, DstMem64 | ModRM | Lock, 0, 0, 0, 0, 0, 0,
};
static u32 group2_table[] = {
@ -1205,6 +1206,7 @@ done_prefixes:
c->twobyte && (c->b == 0xb6 || c->b == 0xb7));
break;
case DstMem:
case DstMem64:
if ((c->d & ModRM) && c->modrm_mod == 3) {
c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
c->dst.type = OP_REG;
@ -1214,7 +1216,10 @@ done_prefixes:
}
c->dst.type = OP_MEM;
c->dst.ptr = (unsigned long *)c->modrm_ea;
c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
if ((c->d & DstMask) == DstMem64)
c->dst.bytes = 8;
else
c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
c->dst.val = 0;
if (c->d & BitOp) {
unsigned long mask = ~(c->dst.bytes * 8 - 1);
@ -1706,12 +1711,7 @@ static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops)
{
struct decode_cache *c = &ctxt->decode;
u64 old, new;
int rc;
rc = ops->read_emulated(c->modrm_ea, &old, 8, ctxt->vcpu);
if (rc != X86EMUL_CONTINUE)
return rc;
u64 old = c->dst.orig_val;
if (((u32) (old >> 0) != (u32) c->regs[VCPU_REGS_RAX]) ||
((u32) (old >> 32) != (u32) c->regs[VCPU_REGS_RDX])) {
@ -1719,15 +1719,12 @@ static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
c->regs[VCPU_REGS_RAX] = (u32) (old >> 0);
c->regs[VCPU_REGS_RDX] = (u32) (old >> 32);
ctxt->eflags &= ~EFLG_ZF;
} else {
new = ((u64)c->regs[VCPU_REGS_RCX] << 32) |
c->dst.val = ((u64)c->regs[VCPU_REGS_RCX] << 32) |
(u32) c->regs[VCPU_REGS_RBX];
rc = ops->cmpxchg_emulated(c->modrm_ea, &old, &new, 8, ctxt->vcpu);
if (rc != X86EMUL_CONTINUE)
return rc;
ctxt->eflags |= EFLG_ZF;
c->lock_prefix = 1;
}
return X86EMUL_CONTINUE;
}
@ -3245,7 +3242,6 @@ twobyte_insn:
rc = emulate_grp9(ctxt, ops);
if (rc != X86EMUL_CONTINUE)
goto done;
c->dst.type = OP_NONE;
break;
}
goto writeback;