path: root/virt
diff options
authorChristoffer Dall <christoffer.dall@linaro.org>2015-10-17 19:05:27 +0200
committerChristoffer Dall <christoffer.dall@linaro.org>2015-10-20 18:09:13 +0200
commit0d997491f814c87310a6ad7be30a9049c7150489 (patch)
treee368ad59cc46060514c092f8121bd62f7311e0c4 /virt
parent544c572e03174438b6656ed24a4516b9a9d5f14a (diff)
arm/arm64: KVM: Fix disabled distributor operation
We currently do a single update of the vgic state when the distributor enable/disable control register is accessed and then bypass updating the state for as long as the distributor remains disabled. This is incorrect, because updating the state does not consider the distributor enable bit, and this you can end up in a situation where an interrupt is marked as pending on the CPU interface, but not pending on the distributor, which is an impossible state to be in, and triggers a warning. Consider for example the following sequence of events: 1. An interrupt is marked as pending on the distributor - the interrupt is also forwarded to the CPU interface 2. The guest turns off the distributor (it's about to do a reboot) - we stop updating the CPU interface state from now on 3. The guest disables the pending interrupt - we remove the pending state from the distributor, but don't touch the CPU interface, see point 2. Since the distributor disable bit really means that no interrupts should be forwarded to the CPU interface, we modify the code to keep updating the internal VGIC state, but always set the CPU interface pending bits to zero when the distributor is disabled. Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Diffstat (limited to 'virt')
1 files changed, 6 insertions, 5 deletions
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 58b125676785..66c66165e712 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1012,6 +1012,12 @@ static int compute_pending_for_cpu(struct kvm_vcpu *vcpu)
pend_percpu = vcpu->arch.vgic_cpu.pending_percpu;
pend_shared = vcpu->arch.vgic_cpu.pending_shared;
+ if (!dist->enabled) {
+ bitmap_zero(pend_percpu, VGIC_NR_PRIVATE_IRQS);
+ bitmap_zero(pend_shared, nr_shared);
+ return 0;
+ }
pending = vgic_bitmap_get_cpu_map(&dist->irq_pending, vcpu_id);
enabled = vgic_bitmap_get_cpu_map(&dist->irq_enabled, vcpu_id);
bitmap_and(pend_percpu, pending, enabled, VGIC_NR_PRIVATE_IRQS);
@@ -1039,11 +1045,6 @@ void vgic_update_state(struct kvm *kvm)
struct kvm_vcpu *vcpu;
int c;
- if (!dist->enabled) {
- set_bit(0, dist->irq_pending_on_cpu);
- return;
- }
kvm_for_each_vcpu(c, vcpu, kvm) {
if (compute_pending_for_cpu(vcpu))
set_bit(c, dist->irq_pending_on_cpu);