KVM: arm/arm64: vgic: Kick new VCPU on interrupt migration

When vgic_prune_ap_list() finds an interrupt that needs to be migrated
to a new VCPU, we should notify this VCPU of the pending interrupt,
since it requires immediate action.
Kick this VCPU once we have added the new IRQ to the list, but only
after dropping the locks.

Reported-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index e74baec76361..4b6d72939c42 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -594,6 +594,7 @@ retry:
 
         list_for_each_entry_safe(irq, tmp, &vgic_cpu->ap_list_head, ap_list) {
                 struct kvm_vcpu *target_vcpu, *vcpuA, *vcpuB;
+                bool target_vcpu_needs_kick = false;
 
                 spin_lock(&irq->irq_lock);
 
@@ -664,11 +665,18 @@ retry:
                         list_del(&irq->ap_list);
                         irq->vcpu = target_vcpu;
                         list_add_tail(&irq->ap_list, &new_cpu->ap_list_head);
+                        target_vcpu_needs_kick = true;
                 }
 
                 spin_unlock(&irq->irq_lock);
                 spin_unlock(&vcpuB->arch.vgic_cpu.ap_list_lock);
                 spin_unlock_irqrestore(&vcpuA->arch.vgic_cpu.ap_list_lock, flags);
+
+                if (target_vcpu_needs_kick) {
+                        kvm_make_request(KVM_REQ_IRQ_PENDING, target_vcpu);
+                        kvm_vcpu_kick(target_vcpu);
+                }
+
                 goto retry;
         }