I noticed that apic test from kvm-unit-tests always hangs on my EPYC 7401P,
the hanging test nmi-after-sti is trying to deliver 30000 NMIs and tracing
shows that we're sometimes able to deliver a few but never all.
When we're trying to inject an NMI we may fail to do so immediately for
various reasons, however, we still need to inject it so enable_nmi_window()
arms nmi_singlestep mode. #DB occurs as expected, but we're not checking
for pending NMIs before entering the guest and unless there's a different
event to process, the NMI will never get delivered.
Make KVM_REQ_EVENT request on the vCPU from db_interception() to make sure
pending NMIs are checked and possibly injected.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
- I have to admit my RFC didn't gain much popularity, re-sending as
non-RFC.
---
arch/x86/kvm/svm.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 426039285fd1..69a0edb23c28 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2692,6 +2692,7 @@ static int npf_interception(struct vcpu_svm *svm)
static int db_interception(struct vcpu_svm *svm)
{
struct kvm_run *kvm_run = svm->vcpu.run;
+ struct kvm_vcpu *vcpu = &svm->vcpu;
if (!(svm->vcpu.guest_debug &
(KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP)) &&
@@ -2702,6 +2703,8 @@ static int db_interception(struct vcpu_svm *svm)
if (svm->nmi_singlestep) {
disable_nmi_singlestep(svm);
+ /* Make sure we check for pending NMIs upon entry */
+ kvm_make_request(KVM_REQ_EVENT, vcpu);
}
if (svm->vcpu.guest_debug &
--
2.20.1
