KVM: X86 emulator: fix source operand decoding for 8bit mov[zs]x instructions

Source operand for one byte mov[zs]x is decoded incorrectly if it is in
high byte register. Fix that.

Cc: stable@vger.kernel.org
Signed-off-by: Gleb Natapov <gleb@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 46f63b8d09f43e8887c134f61e347a2181ab3ca3..8e517bba6a7c9434099139ecbb82a5017ca49cbf 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -4172,6 +4172,10 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
                break;
        case OpMem8:
                ctxt->memop.bytes = 1;
+               if (ctxt->memop.type == OP_REG) {
+                       ctxt->memop.addr.reg = decode_register(ctxt, ctxt->modrm_rm, 1);
+                       fetch_register_operand(&ctxt->memop);
+               }
                goto mem_common;
        case OpMem16:
                ctxt->memop.bytes = 2;