KVM: x86: zero apic_arb_prio on reset

BSP doesn't get INIT so its apic_arb_prio isn't zeroed after reboot.
BSP won't get lowest priority interrupts until other VCPUs get enough
interrupts to match their pre-reboot apic_arb_prio.

That behavior doesn't fit into KVM's round-robin-like interpretation of
lowest priority delivery ... userspace should KVM_SET_LAPIC on reset, so
just zero apic_arb_prio there.

Reported-by: Yuki Shibuya <shibuya.yk@ncos.nec.co.jp>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 168b8759bd736e6020f83b97e90fc1c03af02fba..ecd4ea1d28a8ce01b5b693f5b7d8a953e50131a1 100644 (file)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1918,6 +1918,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
        kvm_make_request(KVM_REQ_EVENT, vcpu);
        if (ioapic_in_kernel(vcpu->kvm))
                kvm_rtc_eoi_tracking_restore_one(vcpu);
+
+       vcpu->arch.apic_arb_prio = 0;
 }
 
 void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)