KVM: x86 emulator: add support for writing back the source operand
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>
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8db0010..a4c266e 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -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 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 @@
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