kvm: x86: correctly reset dest_map->vector when restoring LAPIC state

When userspace sends KVM_SET_LAPIC, KVM schedules a check between
the vCPU's IRR and ISR and the IOAPIC redirection table, in order
to re-establish the IOAPIC's dest_map (the list of CPUs servicing
the real-time clock interrupt with the corresponding vectors).

However, __rtc_irq_eoi_tracking_restore_one was forgetting to
set dest_map->vectors.  Because of this, the IOAPIC did not process
the real-time clock interrupt EOI, ioapic->rtc_status.pending_eoi
got stuck at a non-zero value, and further RTC interrupts were
reported to userspace as coalesced.

Fixes: 9e4aabe2bb3454c83dac8139cf9974503ee044db
Fixes: 4d99ba898dd0c521ca6cdfdde55c9b58aea3cb3d
Cc: stable@vger.kernel.org
Cc: Joerg Roedel <jroedel@suse.de>
Cc: David Gilbert <dgilbert@redhat.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index 5f42d038fcb4..c7220ba94aa7 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -109,6 +109,7 @@ static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
 {
         bool new_val, old_val;
         struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
+        struct dest_map *dest_map = &ioapic->rtc_status.dest_map;
         union kvm_ioapic_redirect_entry *e;
 
         e = &ioapic->redirtbl[RTC_GSI];
@@ -117,16 +118,17 @@ static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
                 return;
 
         new_val = kvm_apic_pending_eoi(vcpu, e->fields.vector);
-        old_val = test_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map.map);
+        old_val = test_bit(vcpu->vcpu_id, dest_map->map);
 
         if (new_val == old_val)
                 return;
 
         if (new_val) {
-                __set_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map.map);
+                __set_bit(vcpu->vcpu_id, dest_map->map);
+                dest_map->vectors[vcpu->vcpu_id] = e->fields.vector;
                 ioapic->rtc_status.pending_eoi++;
         } else {
-                __clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map.map);
+                __clear_bit(vcpu->vcpu_id, dest_map->map);
                 ioapic->rtc_status.pending_eoi--;
                 rtc_status_pending_eoi_check_valid(ioapic);
         }