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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 4/5] KVM: arm64: vgic-v3: Don't require IRQs be disabled for LPI xarray lock
Date: Wed,  3 Sep 2025 23:23:47 -0700	[thread overview]
Message-ID: <20250904062348.223976-5-oliver.upton@linux.dev> (raw)
In-Reply-To: <20250904062348.223976-1-oliver.upton@linux.dev>

Now that the LPI xarray is only read with IRQs disabled, relax the
locking on the xarray to a non-IRQ disabling spinlock.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/vgic/vgic-init.c |  2 +-
 arch/arm64/kvm/vgic/vgic-its.c  |  7 +++----
 arch/arm64/kvm/vgic/vgic.c      | 13 ++++++-------
 3 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index 4c777136ea5f..4c3c0d82e476 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -53,7 +53,7 @@ void kvm_vgic_early_init(struct kvm *kvm)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
 
-	xa_init_flags(&dist->lpi_xa, XA_FLAGS_LOCK_IRQ);
+	xa_init(&dist->lpi_xa);
 }
 
 /* CREATION */
diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index f162206adb48..ce3e3ed3f29f 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -78,7 +78,6 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
 	struct vgic_irq *irq = vgic_get_irq(kvm, intid), *oldirq;
-	unsigned long flags;
 	int ret;
 
 	/* In this case there is no put, since we keep the reference. */
@@ -89,7 +88,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
 	if (!irq)
 		return ERR_PTR(-ENOMEM);
 
-	ret = xa_reserve_irq(&dist->lpi_xa, intid, GFP_KERNEL_ACCOUNT);
+	ret = xa_reserve(&dist->lpi_xa, intid, GFP_KERNEL_ACCOUNT);
 	if (ret) {
 		kfree(irq);
 		return ERR_PTR(ret);
@@ -104,7 +103,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
 	irq->target_vcpu = vcpu;
 	irq->group = 1;
 
-	xa_lock_irqsave(&dist->lpi_xa, flags);
+	xa_lock(&dist->lpi_xa);
 
 	/*
 	 * There could be a race with another vgic_add_lpi(), so we need to
@@ -126,7 +125,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
 	}
 
 out_unlock:
-	xa_unlock_irqrestore(&dist->lpi_xa, flags);
+	xa_unlock(&dist->lpi_xa);
 
 	if (ret)
 		return ERR_PTR(ret);
diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index 480391a0dcad..a21b482844ce 100644
--- a/arch/arm64/kvm/vgic/vgic.c
+++ b/arch/arm64/kvm/vgic/vgic.c
@@ -28,7 +28,7 @@ struct vgic_global kvm_vgic_global_state __ro_after_init = {
  *     kvm->arch.config_lock (mutex)
  *       its->cmd_lock (mutex)
  *         its->its_lock (mutex)
- *           vgic_dist->lpi_xa.xa_lock		must be taken with IRQs disabled
+ *           vgic_dist->lpi_xa.xa_lock
  *             vgic_cpu->ap_list_lock		must be taken with IRQs disabled
  *               vgic_irq->irq_lock		must be taken with IRQs disabled
  *
@@ -141,30 +141,29 @@ static __must_check bool vgic_put_irq_norelease(struct kvm *kvm, struct vgic_irq
 void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
-	unsigned long flags;
 
 	if (!__vgic_put_irq(kvm, irq))
 		return;
 
-	xa_lock_irqsave(&dist->lpi_xa, flags);
+	xa_lock(&dist->lpi_xa);
 	vgic_release_lpi_locked(dist, irq);
-	xa_unlock_irqrestore(&dist->lpi_xa, flags);
+	xa_unlock(&dist->lpi_xa);
 }
 
 static void vgic_release_deleted_lpis(struct kvm *kvm)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
-	unsigned long flags, intid;
+	unsigned long intid;
 	struct vgic_irq *irq;
 
-	xa_lock_irqsave(&dist->lpi_xa, flags);
+	xa_lock(&dist->lpi_xa);
 
 	xa_for_each(&dist->lpi_xa, intid, irq) {
 		if (irq->pending_release)
 			vgic_release_lpi_locked(dist, irq);
 	}
 
-	xa_unlock_irqrestore(&dist->lpi_xa, flags);
+	xa_unlock(&dist->lpi_xa);
 }
 
 void vgic_flush_pending_lpis(struct kvm_vcpu *vcpu)
-- 
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 ` Oliver Upton [this message]
2025-09-05  8:13   ` [PATCH 4/5] KVM: arm64: vgic-v3: Don't require IRQs be disabled for LPI xarray lock Marc Zyngier
2025-09-05  8:55     ` Oliver Upton
2025-09-04  6:23 ` [PATCH 5/5] KVM: arm64: vgic-v3: Indicate vgic_put_irq() may take " Oliver Upton
2025-09-04 10:25   ` 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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