Commit 481c9ee8 authored by Oliver Upton's avatar Oliver Upton Committed by Marc Zyngier
Browse files

KVM: arm64: vgic-its: Get rid of the lpi_list_lock 



The last genuine use case for the lpi_list_lock was the global LPI
translation cache, which has been removed in favor of a per-ITS xarray.
Remove a layer from the locking puzzle by getting rid of it.

vgic_add_lpi() still has a critical section that needs to protect
against the insertion of other LPIs; change it to take the LPI xarray's
xa_lock to retain this property.

Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240422200158.2606761-13-oliver.upton@linux.dev


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent ec39bbfd

arch/arm64/kvm/vgic/vgic-init.c

+0 −1
Original line number Diff line number Diff line
@@ -53,7 +53,6 @@ void kvm_vgic_early_init(struct kvm *kvm) 
{

	struct vgic_dist *dist = &kvm->arch.vgic;



	raw_spin_lock_init(&dist->lpi_list_lock);

	xa_init_flags(&dist->lpi_xa, XA_FLAGS_LOCK_IRQ);

}

arch/arm64/kvm/vgic/vgic-its.c

+3 −3
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid, 
	irq->target_vcpu = vcpu;

	irq->group = 1;



	raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);

	xa_lock_irqsave(&dist->lpi_xa, flags);



	/*

	 * There could be a race with another vgic_add_lpi(), so we need to
@@ -84,14 +84,14 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid, 
		goto out_unlock;

	}



	ret = xa_err(xa_store(&dist->lpi_xa, intid, irq, 0));

	ret = xa_err(__xa_store(&dist->lpi_xa, intid, irq, 0));

	if (ret) {

		xa_release(&dist->lpi_xa, intid);

		kfree(irq);

	}



out_unlock:

	raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);

	xa_unlock_irqrestore(&dist->lpi_xa, flags);



	if (ret)

		return ERR_PTR(ret);

arch/arm64/kvm/vgic/vgic.c

+2 −3
Original line number Diff line number Diff line
@@ -29,7 +29,6 @@ struct vgic_global kvm_vgic_global_state __ro_after_init = { 
 *       its->cmd_lock (mutex)

 *         its->its_lock (mutex)

 *           vgic_cpu->ap_list_lock		must be taken with IRQs disabled

 *             kvm->lpi_list_lock		must be taken with IRQs disabled

 *             vgic_dist->lpi_xa.xa_lock	must be taken with IRQs disabled

 *               vgic_irq->irq_lock		must be taken with IRQs disabled

 *

include/kvm/arm_vgic.h

+0 −3
Original line number Diff line number Diff line
@@ -280,9 +280,6 @@ struct vgic_dist { 
	 */

	u64			propbaser;



	/* Protects the lpi_list. */

	raw_spinlock_t		lpi_list_lock;



#define LPI_XA_MARK_DEBUG_ITER	XA_MARK_0

	struct xarray		lpi_xa;