Patch "kvm: x86: correctly reset dest_map->vector when restoring LAPIC state" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
kvm-x86-correctly-reset-dest_map-vector-when-restoring-lapic-state.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Paolo Bonzini <[email protected]>
Date: Wed, 14 Sep 2016 23:39:12 +0200
Subject: kvm: x86: correctly reset dest_map->vector when restoring LAPIC state
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From: Paolo Bonzini <[email protected]>

commit b0eaf4506f5f95d15d6731d72c0ddf4a2179eefa upstream.

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.

---
 arch/x86/kvm/ioapic.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

@@ -109,6 +109,7 @@ static void __rtc_irq_eoi_tracking_resto
 {
 	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_resto
 		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);
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/mips-kvm-check-for-pfn-noslot-case.patch queue-4.7/kvm-x86-correctly-reset-dest_map-vector-when-restoring-lapic-state.patch