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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>,
	Ben Horgan <ben.horgan@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>
Subject: [PATCH v2 6/6] KVM: arm64: vgic-v3: Indicate vgic_put_irq() may take LPI xarray lock
Date: Fri,  5 Sep 2025 03:05:31 -0700	[thread overview]
Message-ID: <20250905100531.282980-7-oliver.upton@linux.dev> (raw)
In-Reply-To: <20250905100531.282980-1-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.

Reviewed-by: Marc Zyngier <maz@kernel.org>
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..3b247041a130 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:[~2025-09-05 14:21 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-05 10:05 [PATCH v2 0/6] KVM: arm64: vgic-v3: Fix yet another lock ordering turd Oliver Upton
2025-09-05 10:05 ` [PATCH v2 1/6] KVM: arm64: vgic: Drop stale comment on IRQ active state Oliver Upton
2025-09-05 10:05 ` [PATCH v2 2/6] KVM: arm64: vgic-v3: Use bare refcount for VGIC LPIs Oliver Upton
2025-09-05 10:05 ` [PATCH v2 3/6] KVM: arm64: Spin off release helper from vgic_put_irq() Oliver Upton
2025-09-05 10:05 ` [PATCH v2 4/6] KVM: arm64: vgic-v3: Erase LPIs from xarray outside of raw spinlocks Oliver Upton
2025-09-05 10:05 ` [PATCH v2 5/6] KVM: arm64: vgic-v3: Don't require IRQs be disabled for LPI xarray lock Oliver Upton
2025-09-05 10:05 ` Oliver Upton [this message]
2025-11-05  9:37   ` [PATCH v2 6/6] KVM: arm64: vgic-v3: Indicate vgic_put_irq() may take " Zenghui Yu
2025-11-05 10:28     ` Marc Zyngier
2025-11-06  0:46       ` Oliver Upton
2025-11-06  0:58         ` Oliver Upton
2025-11-06  3:34           ` Zenghui Yu
2025-09-06  6:11 ` [PATCH v2 0/6] KVM: arm64: vgic-v3: Fix yet another lock ordering turd Oliver Upton

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