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

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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: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240422200158.2606761-13-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Oliver Upton 2024-04-22 20:01:51 +00:00 committed by Marc Zyngier
parent ec39bbfd55
commit 481c9ee846
4 changed files with 5 additions and 10 deletions
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1
arch/arm64/kvm/vgic/vgic-init.c
View File

@ -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);
}

6
arch/arm64/kvm/vgic/vgic-its.c
View File

@ -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);

5
arch/arm64/kvm/vgic/vgic.c
View File

@ -29,9 +29,8 @@ 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
* vgic_dist->lpi_xa.xa_lock must be taken with IRQs disabled
* vgic_irq->irq_lock must be taken with IRQs disabled
*
* As the ap_list_lock might be taken from the timer interrupt handler,
* we have to disable IRQs before taking this lock and everything lower

3
include/kvm/arm_vgic.h
View File

@ -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;