linux-kernel - [PATCH v2 16/23] KVM: arm64: vgic-its: Rely on RCU to protect translation cache reads

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Date: Tue, 13 Feb 2024 09:40:12 +0000
From: Oliver Upton <oliver.upton@...ux.dev>
To: kvmarm@...ts.linux.dev
Cc: kvm@...r.kernel.org,
	Marc Zyngier <maz@...nel.org>,
	James Morse <james.morse@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-kernel@...r.kernel.org,
	Oliver Upton <oliver.upton@...ux.dev>
Subject: [PATCH v2 16/23] KVM: arm64: vgic-its: Rely on RCU to protect translation cache reads

Stop taking the lpi_list_lock when reading the LPI translation cache.

Signed-off-by: Oliver Upton <oliver.upton@...ux.dev>
---
 arch/arm64/kvm/vgic/vgic-its.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 55463eb84763..0e449f8c1f01 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -593,15 +593,14 @@ static struct vgic_irq *vgic_its_check_cache(struct kvm *kvm, phys_addr_t db,
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
 	struct vgic_irq *irq;
-	unsigned long flags;
 
-	raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
+	rcu_read_lock();
 
 	irq = __vgic_its_check_cache(dist, db, devid, eventid);
 	if (!vgic_try_get_irq_kref(irq))
 		irq = NULL;
 
-	raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
+	rcu_read_unlock();
 
 	return irq;
 }
-- 
2.43.0.687.g38aa6559b0-goog