KVM: arm/arm64: vgic: Only set underflow when actually out of LRs

We currently assume that all the interrupts in our AP list will be
queued to LRs, but that's not necessarily the case, because some of them
could have been migrated away to different VCPUs and only the VCPU
thread itself can remove interrupts from its AP list.

Therefore, slightly change the logic to only setting the underflow
interrupt when we actually run out of LRs.

As it turns out, this allows us to further simplify the handling in
vgic_sync_hwstate in later patches.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 104329139f24b3723ea9d7ba73c13929f43f92f4..442f7df2a46a173d8d7fd28c11ea6a4a799d8d75 100644 (file)
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -601,10 +601,8 @@ static void vgic_flush_lr_state(struct kvm_vcpu *vcpu)
 
        DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
 
-       if (compute_ap_list_depth(vcpu) > kvm_vgic_global_state.nr_lr) {
-               vgic_set_underflow(vcpu);
+       if (compute_ap_list_depth(vcpu) > kvm_vgic_global_state.nr_lr)
                vgic_sort_ap_list(vcpu);
-       }
 
        list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
                spin_lock(&irq->irq_lock);
@@ -623,8 +621,12 @@ static void vgic_flush_lr_state(struct kvm_vcpu *vcpu)
 next:
                spin_unlock(&irq->irq_lock);
 
-               if (count == kvm_vgic_global_state.nr_lr)
+               if (count == kvm_vgic_global_state.nr_lr) {
+                       if (!list_is_last(&irq->ap_list,
+                                         &vgic_cpu->ap_list_head))
+                               vgic_set_underflow(vcpu);
                        break;
+               }
        }
 
        vcpu->arch.vgic_cpu.used_lrs = count;