irqchip/gic-v4: Fix ordering between vmapp and vpe locks
The recently established lock ordering mandates that the per-VM
vmapp_lock is acquired before taking the per-VPE lock.
As it turns out, its_vpe_set_affinity() takes the VPE lock, and
then calls into its_send_vmovp(), which itself takes the vmapp
lock. Obviously, this is a lock order violation.
As its_send_vmovp() is only called from its_vpe_set_affinity(),
hoist the vmapp locking from the former into the latter, restoring
the expected order.
Fixes: f0eb154c39471 ("irqchip/gic-v4: Substitute vmovp_lock for a per-VM lock")
Reported-by: Zhou Wang <wangzhou1@hisilicon.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240818171625.3030584-1-maz@kernel.org
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 9b34596..fdec478 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1330,12 +1330,6 @@ static void its_send_vmovp(struct its_vpe *vpe)
}
/*
- * Protect against concurrent updates of the mapping state on
- * individual VMs.
- */
- guard(raw_spinlock_irqsave)(&vpe->its_vm->vmapp_lock);
-
- /*
* Yet another marvel of the architecture. If using the
* its_list "feature", we need to make sure that all ITSs
* receive all VMOVP commands in the same order. The only way
@@ -3824,7 +3818,14 @@ static int its_vpe_set_affinity(struct irq_data *d,
* protect us, and that we must ensure nobody samples vpe->col_idx
* during the update, hence the lock below which must also be
* taken on any vLPI handling path that evaluates vpe->col_idx.
+ *
+ * Finally, we must protect ourselves against concurrent updates of
+ * the mapping state on this VM should the ITS list be in use (see
+ * the shortcut in its_send_vmovp() otherewise).
*/
+ if (its_list_map)
+ raw_spin_lock(&vpe->its_vm->vmapp_lock);
+
from = vpe_to_cpuid_lock(vpe, &flags);
table_mask = gic_data_rdist_cpu(from)->vpe_table_mask;
@@ -3854,6 +3855,9 @@ static int its_vpe_set_affinity(struct irq_data *d,
irq_data_update_effective_affinity(d, cpumask_of(cpu));
vpe_to_cpuid_unlock(vpe, flags);
+ if (its_list_map)
+ raw_spin_unlock(&vpe->its_vm->vmapp_lock);
+
return IRQ_SET_MASK_OK_DONE;
}
