linux-kernel - [PATCH v4 04/10] KVM: arm64: vgic-its: Walk the LPI xarray in vgic_copy_lpi

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Message-ID: <20240221054253.3848076-5-oliver.upton@linux.dev>
Date: Wed, 21 Feb 2024 05:42:47 +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,
	Eric Auger <eric.auger@...hat.com>,
	Oliver Upton <oliver.upton@...ux.dev>
Subject: [PATCH v4 04/10] KVM: arm64: vgic-its: Walk the LPI xarray in vgic_copy_lpi_list()

Start iterating the LPI xarray in anticipation of removing the LPI
linked-list.

Signed-off-by: Oliver Upton <oliver.upton@...ux.dev>
---
 arch/arm64/kvm/vgic/vgic-its.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index fb2d3c356984..b9874dc04608 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -327,6 +327,8 @@ static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
 	return 0;
 }
 
+#define GIC_LPI_MAX_INTID	((1 << INTERRUPT_ID_BITS_ITS) - 1)
+
 /*
  * Create a snapshot of the current LPIs targeting @vcpu, so that we can
  * enumerate those LPIs without holding any lock.
@@ -335,6 +337,7 @@ static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
 int vgic_copy_lpi_list(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 **intid_ptr)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
+	XA_STATE(xas, &dist->lpi_xa, GIC_LPI_OFFSET);
 	struct vgic_irq *irq;
 	unsigned long flags;
 	u32 *intids;
@@ -353,7 +356,9 @@ int vgic_copy_lpi_list(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 **intid_ptr)
 		return -ENOMEM;
 
 	raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
-	list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) {
+	rcu_read_lock();
+
+	xas_for_each(&xas, irq, GIC_LPI_MAX_INTID) {
 		if (i == irq_count)
 			break;
 		/* We don't need to "get" the IRQ, as we hold the list lock. */
@@ -361,6 +366,8 @@ int vgic_copy_lpi_list(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 **intid_ptr)
 			continue;
 		intids[i++] = irq->intid;
 	}
+
+	rcu_read_unlock();
 	raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
 
 	*intid_ptr = intids;
-- 
2.44.0.rc0.258.g7320e95886-goog