KVM: x86: bit-ops emulation ignores offset on 64-bit

The current emulation of bit operations ignores the offset from the destination
on 64-bit target memory operands. This patch fixes this behavior.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/emulate.c

@@ -1220,12 +1220,14 @@ static void fetch_bit_operand(struct x86_emulate_ctxt *ctxt)
 	long sv = 0, mask;
 
 	if (ctxt->dst.type == OP_MEM && ctxt->src.type == OP_REG) {
-		mask = ~(ctxt->dst.bytes * 8 - 1);
+		mask = ~((long)ctxt->dst.bytes * 8 - 1);
 
 		if (ctxt->src.bytes == 2)
 			sv = (s16)ctxt->src.val & (s16)mask;
 		else if (ctxt->src.bytes == 4)
 			sv = (s32)ctxt->src.val & (s32)mask;
+		else
+			sv = (s64)ctxt->src.val & (s64)mask;
 
 		ctxt->dst.addr.mem.ea += (sv >> 3);
 	}