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Commit b0eaf450 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

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: 9e4aabe2
Fixes: 4d99ba89
Cc: stable@vger.kernel.org
Cc: Joerg Roedel <jroedel@suse.de>
Cc: David Gilbert <dgilbert@redhat.com>
Reviewed-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 77e5bdf9

arch/x86/kvm/ioapic.c

+5 −3
Original line number Diff line number Diff line
@@ -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);

	}