If bit offset operands is a negative number, BitOp instruction will return wrong value. This patch fix it. Signed-off-by: Wei Yongjun <yjwei@xxxxxxxxxxxxxx> --- arch/x86/kvm/emulate.c | 24 ++++++++++++++++++------ 1 files changed, 18 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 0e360c6..f48890d 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -724,6 +724,22 @@ done: return rc; } +static void fetch_bit_operand(struct decode_cache *c) +{ + long sv, mask; + + if (c->dst.type == OP_MEM) { + mask = ~(c->dst.bytes * 8 - 1); + + if (c->src.bytes == 2) + sv = (s16)c->src.val & (s16)mask; + else if (c->src.bytes == 4) + sv = (s32)c->src.val & (s32)mask; + + c->dst.addr.mem += (sv >> 3); + } +} + static int read_emulated(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops, unsigned long addr, void *dest, unsigned size) @@ -2646,12 +2662,8 @@ done_prefixes: c->dst.bytes = 8; else c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes; - if (c->dst.type == OP_MEM && (c->d & BitOp)) { - unsigned long mask = ~(c->dst.bytes * 8 - 1); - - c->dst.addr.mem = c->dst.addr.mem + - (c->src.val & mask) / 8; - } + if (c->d & BitOp) + fetch_bit_operand(c); c->dst.orig_val = c->dst.val; break; case DstAcc: -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html