iommu/arm-smmu: Disable interrupts whilst holding the cmdq lock
The cmdq lock is taken whenever we issue commands into the command queue,
which can occur in IRQ context (as a result of unmap) or in process
context (as a result of a threaded IRQ handler or device probe).
This can lead to a theoretical deadlock if the interrupt handler
performing the unmap hits whilst the lock is taken, so explicitly use
the {irqsave,irqrestore} spin_lock accessors for the cmdq lock.
Tested-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index c040e24..5db6931 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -893,6 +893,7 @@
struct arm_smmu_cmdq_ent *ent)
{
u64 cmd[CMDQ_ENT_DWORDS];
+ unsigned long flags;
bool wfe = !!(smmu->features & ARM_SMMU_FEAT_SEV);
struct arm_smmu_queue *q = &smmu->cmdq.q;
@@ -902,7 +903,7 @@
return;
}
- spin_lock(&smmu->cmdq.lock);
+ spin_lock_irqsave(&smmu->cmdq.lock, flags);
while (queue_insert_raw(q, cmd) == -ENOSPC) {
if (queue_poll_cons(q, false, wfe))
dev_err_ratelimited(smmu->dev, "CMDQ timeout\n");
@@ -910,7 +911,7 @@
if (ent->opcode == CMDQ_OP_CMD_SYNC && queue_poll_cons(q, true, wfe))
dev_err_ratelimited(smmu->dev, "CMD_SYNC timeout\n");
- spin_unlock(&smmu->cmdq.lock);
+ spin_unlock_irqrestore(&smmu->cmdq.lock, flags);
}
/* Context descriptor manipulation functions */