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KVM: x86 emulator: add support for writing back the source operand

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Some instructions write back the source operand, not just the destination.
Add support for doing this via the decode flags.

Gleb: add BUG_ON() to prevent source to be memory operand.

Signed-off-by: Avi Kivity <avi.kivity@gmail.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
This commit is contained in:
Avi Kivity 2013-02-09 11:31:44 +02:00 committed by Gleb Natapov
parent f8b5ff2cff
commit fb32b1eda2
1 changed files with 27 additions and 21 deletions
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48
arch/x86/kvm/emulate.c
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@ -155,6 +155,7 @@
#define Avx ((u64)1 << 43) /* Advanced Vector Extensions */
#define Fastop ((u64)1 << 44) /* Use opcode::u.fastop */
#define NoWrite ((u64)1 << 45) /* No writeback */
#define SrcWrite ((u64)1 << 46) /* Write back src operand */
#define X2(x...) x, x
#define X3(x...) X2(x), x
@ -1723,45 +1724,42 @@ static void write_register_operand(struct operand *op)
}
}
static int writeback(struct x86_emulate_ctxt *ctxt)
static int writeback(struct x86_emulate_ctxt *ctxt, struct operand *op)
{
int rc;
if (ctxt->d & NoWrite)
return X86EMUL_CONTINUE;
switch (ctxt->dst.type) {
switch (op->type) {
case OP_REG:
write_register_operand(&ctxt->dst);
write_register_operand(op);
break;
case OP_MEM:
if (ctxt->lock_prefix)
rc = segmented_cmpxchg(ctxt,
ctxt->dst.addr.mem,
&ctxt->dst.orig_val,
&ctxt->dst.val,
ctxt->dst.bytes);
op->addr.mem,
&op->orig_val,
&op->val,
op->bytes);
else
rc = segmented_write(ctxt,
ctxt->dst.addr.mem,
&ctxt->dst.val,
ctxt->dst.bytes);
op->addr.mem,
&op->val,
op->bytes);
if (rc != X86EMUL_CONTINUE)
return rc;
break;
case OP_MEM_STR:
rc = segmented_write(ctxt,
ctxt->dst.addr.mem,
ctxt->dst.data,
ctxt->dst.bytes * ctxt->dst.count);
op->addr.mem,
op->data,
op->bytes * op->count);
if (rc != X86EMUL_CONTINUE)
return rc;
break;
case OP_XMM:
write_sse_reg(ctxt, &ctxt->dst.vec_val, ctxt->dst.addr.xmm);
write_sse_reg(ctxt, &op->vec_val, op->addr.xmm);
break;
case OP_MM:
write_mmx_reg(ctxt, &ctxt->dst.mm_val, ctxt->dst.addr.mm);
write_mmx_reg(ctxt, &op->mm_val, op->addr.mm);
break;
case OP_NONE:
/* no writeback */
@ -4769,9 +4767,17 @@ special_insn:
goto done;
writeback:
rc = writeback(ctxt);
if (rc != X86EMUL_CONTINUE)
goto done;
if (!(ctxt->d & NoWrite)) {
rc = writeback(ctxt, &ctxt->dst);
if (rc != X86EMUL_CONTINUE)
goto done;
}
if (ctxt->d & SrcWrite) {
BUG_ON(ctxt->src.type == OP_MEM || ctxt->src.type == OP_MEM_STR);
rc = writeback(ctxt, &ctxt->src);
if (rc != X86EMUL_CONTINUE)
goto done;
}
/*
* restore dst type in case the decoding will be reused