KVM: x86: smsw emulation is incorrect in 64-bit mode

In 64-bit mode, when the destination is a register, the assignment is done
according to the operand size. Otherwise (memory operand or no 64-bit mode), a
16-bit assignment is performed.

Currently, 16-bit assignment is always done to the destination.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a151f8d24a1d..9b5d97db7631 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3235,7 +3235,8 @@ static int em_lidt(struct x86_emulate_ctxt *ctxt)
 
 static int em_smsw(struct x86_emulate_ctxt *ctxt)
 {
-        ctxt->dst.bytes = 2;
+        if (ctxt->dst.type == OP_MEM)
+                ctxt->dst.bytes = 2;
         ctxt->dst.val = ctxt->ops->get_cr(ctxt, 0);
         return X86EMUL_CONTINUE;
 }