KVM: SVM: Skip instruction on a task switch only when appropriate

If a task switch was initiated because off a task gate in IDT and IDT
was accessed because of an external even the instruction should not
be skipped.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index bba67b70c4b0..8fc6eea148e7 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1828,6 +1828,7 @@ static int task_switch_interception(struct vcpu_svm *svm,
         int reason;
         int int_type = svm->vmcb->control.exit_int_info &
                 SVM_EXITINTINFO_TYPE_MASK;
+        int int_vec = svm->vmcb->control.exit_int_info & SVM_EVTINJ_VEC_MASK;
 
         tss_selector = (u16)svm->vmcb->control.exit_info_1;
 
@@ -1843,8 +1844,14 @@ static int task_switch_interception(struct vcpu_svm *svm,
                 reason = TASK_SWITCH_CALL;
 
 
-        if (reason != TASK_SWITCH_GATE || int_type == SVM_EXITINTINFO_TYPE_SOFT)
-                skip_emulated_instruction(&svm->vcpu);
+        if (reason != TASK_SWITCH_GATE ||
+            int_type == SVM_EXITINTINFO_TYPE_SOFT ||
+            (int_type == SVM_EXITINTINFO_TYPE_EXEPT &&
+             (int_vec == OF_VECTOR || int_vec == BP_VECTOR))) {
+                if (emulate_instruction(&svm->vcpu, kvm_run, 0, 0,
+                                        EMULTYPE_SKIP) != EMULATE_DONE)
+                        return 0;
+        }
 
         return kvm_task_switch(&svm->vcpu, tss_selector, reason);
 }