We do not need to check for reg == RAX for opcodes 0x91...0x97.
Signed-off-by: Denys Vlasenko <dvlas...@redhat.com>
CC: Paolo Bonzini <pbonz...@redhat.com>
CC: Avi Kivity <avi.kiv...@gmail.com>
Signed-off-by: Denys Vlasenko <dvlas...@redhat.com>
CC: Paolo Bonzini <pbonz...@redhat.com>
CC: Avi Kivity <avi.kiv...@gmail.com>
---
arch/x86/kvm/emulate.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 2bc1e81..2dc48a1 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -4544,9 +4544,14 @@ special_insn:
case 0x8d: /* lea r16/r32, m */
ctxt->dst.val = ctxt->src.addr.mem.ea;
break;
- case 0x90 ... 0x97: /* nop / xchg reg, rax */
+ case 0x90: /* nop / xchg reg, rax */
+ /* Not all opcodes 90 are NOPs, only ones which refer to RAX */
+ /* For example, 49 90 is xchg %rax,%r8 */
+ /* Bare 90 and 40 90 (redundant REX prefix) are nop */
if (ctxt->dst.addr.reg == reg_rmw(ctxt, VCPU_REGS_RAX))
break;
+ /* Fall through */
+ case 0x91 ... 0x97: /* xchg reg, rax */
rc = em_xchg(ctxt);
break;
case 0x98: /* cbw/cwde/cdqe */
--
1.8.1.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
