[PATCH] KVM: arm64: vgic: Use list_del_rcu() when flushing pending LPIs

[Hyunwoo Kim]

vgic_v3_fold_lr_state() walks the ap_list from last_lr_irq without holding
the ap_list_lock, relying on vgic_irq being freed via kfree_rcu() and on
interrupts being disabled. vgic_flush_pending_lpis() removes entries with
list_del(), which clobbers a node's next pointer, so when another vCPU
disables LPIs via GICR_CTLR the walk can follow the clobbered next pointer
from a removed node, or from the node that last_lr_irq points to.

Remove entries with list_del_rcu() so that the next pointer stays valid
until the walk completes.

Fixes: 3cfd59f81e0f ("KVM: arm64: GICv3: Handle LR overflow when EOImode==0")
Signed-off-by: Hyunwoo Kim <imv4bel at gmail.com>
---
 arch/arm64/kvm/vgic/vgic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index 1e9fe8764584d..73efc0f95bfb1 100644
--- a/arch/arm64/kvm/vgic/vgic.c
+++ b/arch/arm64/kvm/vgic/vgic.c
@@ -204,7 +204,7 @@ void vgic_flush_pending_lpis(struct kvm_vcpu *vcpu)
 	list_for_each_entry_safe(irq, tmp, &vgic_cpu->ap_list_head, ap_list) {
 		if (irq_is_lpi(vcpu->kvm, irq->intid)) {
 			raw_spin_lock(&irq->irq_lock);
-			list_del(&irq->ap_list);
+			list_del_rcu(&irq->ap_list);
 			irq->vcpu = NULL;
 			raw_spin_unlock(&irq->irq_lock);
 			deleted |= vgic_put_irq_norelease(vcpu->kvm, irq);
-- 
2.43.0