KVM: x86: svm: make sure NMI is injected after nmi_singlestep
authorVitaly Kuznetsov <vkuznets@redhat.com>
Wed, 3 Apr 2019 14:06:42 +0000 (16:06 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 27 Apr 2019 07:36:33 +0000 (09:36 +0200)
commitc9e34935a3514d083cc2787f874fee786c775c6c
tree23eda0e1b5528794c9b71a538523e970a778733b
parent18cf09a817714d7702f4dfa0956abefd4b4e2f63
KVM: x86: svm: make sure NMI is injected after nmi_singlestep

commit 99c221796a810055974b54c02e8f53297e48d146 upstream.

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@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/x86/kvm/svm.c