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: NGleb Natapov <gleb@redhat.com>

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;