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Commit 8ded2909 authored by Will Deacon's avatar Will Deacon
Browse files

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: default avatarJean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent bcfced15

drivers/iommu/arm-smmu-v3.c

+3 −2
Original line number Diff line number Diff line
@@ -893,6 +893,7 @@ static void arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu, 
				    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 @@ static void arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu, 
		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 @@ static void arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu, 


	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 */