unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
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KVM: arm64: vgic: Use atomics to count LPIs

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Switch to using atomics for LPI accounting, allowing vgic_irq references
to be dropped in parallel.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240221054253.3848076-7-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Oliver Upton 2024-02-21 05:42:49 +00:00
parent 9880835af7
commit 05f4d4f5d4
4 changed files with 6 additions and 6 deletions
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2
arch/arm64/kvm/vgic/vgic-debug.c
View file

@ -149,7 +149,7 @@ static void print_dist_state(struct seq_file *s, struct vgic_dist *dist)
seq_printf(s, "vgic_model:\t%s\n", v3 ? "GICv3" : "GICv2");
seq_printf(s, "nr_spis:\t%d\n", dist->nr_spis);
if (v3)
seq_printf(s, "nr_lpis:\t%d\n", dist->lpi_list_count);
seq_printf(s, "nr_lpis:\t%d\n", atomic_read(&dist->lpi_count));
seq_printf(s, "enabled:\t%d\n", dist->enabled);
seq_printf(s, "\n");

4
arch/arm64/kvm/vgic/vgic-its.c
View file

@ -96,7 +96,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
goto out_unlock;
}
dist->lpi_list_count++;
atomic_inc(&dist->lpi_count);
out_unlock:
raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
@ -346,7 +346,7 @@ int vgic_copy_lpi_list(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 **intid_ptr)
* command). If coming from another path (such as enabling LPIs),
* we must be careful not to overrun the array.
*/
irq_count = READ_ONCE(dist->lpi_list_count);
irq_count = atomic_read(&dist->lpi_count);
intids = kmalloc_array(irq_count, sizeof(intids[0]), GFP_KERNEL_ACCOUNT);
if (!intids)
return -ENOMEM;

2
arch/arm64/kvm/vgic/vgic.c
View file

@ -123,7 +123,7 @@ void __vgic_put_lpi_locked(struct kvm *kvm, struct vgic_irq *irq)
return;
xa_erase(&dist->lpi_xa, irq->intid);
dist->lpi_list_count--;
atomic_dec(&dist->lpi_count);
kfree(irq);
}

4
include/kvm/arm_vgic.h
View file

@ -273,10 +273,10 @@ struct vgic_dist {
*/
u64 propbaser;
/* Protects the lpi_list and the count value below. */
/* Protects the lpi_list. */
raw_spinlock_t lpi_list_lock;
struct xarray lpi_xa;
int lpi_list_count;
atomic_t lpi_count;
/* LPI translation cache */
struct list_head lpi_translation_cache;