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From: Oliver Upton <oliver.upton@linux.dev>
To: kvmarm@lists.linux.dev
Cc: Marc Zyngier <maz@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Oliver Upton <oliver.upton@linux.dev>
Subject: [PATCH 5/5] KVM: arm64: vgic-v3: Indicate vgic_put_irq() may take LPI xarray lock
Date: Wed,  3 Sep 2025 23:23:48 -0700	[thread overview]
Message-ID: <20250904062348.223976-6-oliver.upton@linux.dev> (raw)
In-Reply-To: <20250904062348.223976-1-oliver.upton@linux.dev>

The release path on LPIs is quite rare, meaning it can be difficult to
find lock ordering bugs on the LPI xarray's spinlock. Tell lockdep that
vgic_put_irq() might acquire the xa_lock to make unsafe patterns more
obvious.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/vgic/vgic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index a21b482844ce..e61b95167ed1 100644
--- a/arch/arm64/kvm/vgic/vgic.c
+++ b/arch/arm64/kvm/vgic/vgic.c
@@ -142,6 +142,9 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
 
+	if (irq->intid > VGIC_MIN_LPI)
+		might_lock(&dist->lpi_xa.xa_lock);
+
 	if (!__vgic_put_irq(kvm, irq))
 		return;
 
-- 
2.39.5


  parent reply	other threads:[~2025-09-04  7:28 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-04  6:23 [PATCH 0/5] KVM: arm64: vgic-v3: Fix yet another lock ordering turd Oliver Upton
2025-09-04  6:23 ` [PATCH 1/5] KVM: arm64: vgic-v3: Use bare refcount for VGIC LPIs Oliver Upton
2025-09-04  6:23 ` [PATCH 2/5] KVM: arm64: Spin off release helper from vgic_put_irq() Oliver Upton
2025-09-04  6:23 ` [PATCH 3/5] KVM: arm64: vgic-v3: Erase LPIs from xarray outside of raw spinlocks Oliver Upton
2025-09-05  7:44   ` Marc Zyngier
2025-09-05  7:19     ` Oliver Upton
2025-09-04  6:23 ` [PATCH 4/5] KVM: arm64: vgic-v3: Don't require IRQs be disabled for LPI xarray lock Oliver Upton
2025-09-05  8:13   ` Marc Zyngier
2025-09-05  8:55     ` Oliver Upton
2025-09-04  6:23 ` Oliver Upton [this message]
2025-09-04 10:25   ` [PATCH 5/5] KVM: arm64: vgic-v3: Indicate vgic_put_irq() may take " Ben Horgan
2025-09-04  8:19     ` Oliver Upton
2025-09-05  8:29 ` [PATCH 0/5] KVM: arm64: vgic-v3: Fix yet another lock ordering turd Marc Zyngier

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