KVM: x86 emulator: fix cli/sti instruction emulation

If IOPL check fail, the cli/sti emulate GP and then we should
skip writeback since the default write OP is OP_REG.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8337567a0f44..286572a5675b 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2979,17 +2979,19 @@ special_insn:
                 c->dst.type = OP_NONE;  /* Disable writeback. */
                 break;
         case 0xfa: /* cli */
-                if (emulator_bad_iopl(ctxt, ops))
+                if (emulator_bad_iopl(ctxt, ops)) {
                         emulate_gp(ctxt, 0);
-                else {
+                        goto done;
+                } else {
                         ctxt->eflags &= ~X86_EFLAGS_IF;
                         c->dst.type = OP_NONE;  /* Disable writeback. */
                 }
                 break;
         case 0xfb: /* sti */
-                if (emulator_bad_iopl(ctxt, ops))
+                if (emulator_bad_iopl(ctxt, ops)) {
                         emulate_gp(ctxt, 0);
-                else {
+                        goto done;
+                } else {
                         ctxt->interruptibility = KVM_X86_SHADOW_INT_STI;
                         ctxt->eflags |= X86_EFLAGS_IF;
                         c->dst.type = OP_NONE;  /* Disable writeback. */