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KVM: arm64: vgic: Check the interrupt is still ours before migrating it

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vgic_prune_ap_list() drops both ap_list_lock and irq_lock while migrating
an interrupt to another vCPU. After reacquiring the locks it only checks
that the affinity is unchanged (target_vcpu == vgic_target_oracle(irq))
before moving the interrupt, which assumes that an interrupt whose affinity
is preserved is still queued on this vCPU's ap_list.

That assumption no longer holds if the interrupt is taken off the ap_list
while the locks are dropped. vgic_flush_pending_lpis() removes the
interrupt from the list and sets irq->vcpu to NULL, but leaves
enabled/pending/target_vcpu untouched. As the interrupt is still enabled
and pending, vgic_target_oracle() returns the same target_vcpu, so the
affinity check passes and list_del() is run a second time on an entry that
has already been removed.

Also check that the interrupt is still assigned to this vCPU
(irq->vcpu == vcpu) before moving it.

Fixes: 0919e84c0f ("KVM: arm/arm64: vgic-new: Add IRQ sync/flush framework")
Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
Link: https://patch.msgid.link/aiHnI1mu6SGQrgnz@v4bel
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
This commit is contained in:
Hyunwoo Kim 2026-06-05 05:59:15 +09:00 committed by Marc Zyngier
parent 7258770e58
commit 0074b82cdf
1 changed files with 6 additions and 5 deletions
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11
arch/arm64/kvm/vgic/vgic.c
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@ -820,15 +820,16 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
raw_spin_lock(&irq->irq_lock);
/*
* If the affinity has been preserved, move the
* interrupt around. Otherwise, it means things have
* changed while the interrupt was unlocked, and we
* need to replay this.
* If the interrupt is still ours and its affinity has
* been preserved, move it around. Otherwise, it means
* things have changed while the interrupt was unlocked
* (it may even have been taken off the list with its
* affinity left untouched), and we need to replay this.
*
* In all cases, we cannot trust the list not to have
* changed, so we restart from the beginning.
*/
if (target_vcpu == vgic_target_oracle(irq)) {
if (irq->vcpu == vcpu && target_vcpu == vgic_target_oracle(irq)) {
struct vgic_cpu *new_cpu = &target_vcpu->arch.vgic_cpu;
list_del(&irq->ap_list);