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Commit 989471cc authored by Mitchel Humpherys's avatar Mitchel Humpherys Committed by Matt Wagantall
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iommu/arm-smmu: convert atos spinlock to a mutex 



Because of a hardware errata, arm_smmu_iova_to_phys_hard will soon be
making a TZ call to do a workaround.  However, we're currently using a
spinlock to ensure atomicity of ATOS due to another hardware errata, but
scm_call is a sleeping function, so this results in a sleeping BUG.  Fix
this by making the atos lock a mutex instead of a spinlock.

This isn't exactly correct since iommu_iova_to_phys itself might be
called from atomic context, so we really shouldn't be taking a mutex.
However, we don't seem to have any use cases where it will be called
from atomic context, but we should revert all of this and go back to a
spinlock as soon as this hardware errata goes away (which will happen
when Thulium v1 dies).

Change-Id: I61ea37bb3e6989fe5db43c4e828fc6473885db1e
Signed-off-by: default avatarMitchel Humpherys <mitchelh@codeaurora.org>
parent 27e7a6ba

drivers/iommu/arm-smmu.c

+5 −6
Original line number Diff line number Diff line
@@ -463,7 +463,7 @@ struct arm_smmu_device { 
	struct arm_smmu_impl_def_reg	*impl_def_attach_registers;

	unsigned int			num_impl_def_attach_registers;



	spinlock_t			atos_lock;

	struct mutex			atos_lock;

};



struct arm_smmu_cfg {
@@ -1948,7 +1948,6 @@ static phys_addr_t arm_smmu_iova_to_phys_hard(struct iommu_domain *domain, 
	void __iomem *cb_base;

	u32 tmp;

	u64 phys;

	unsigned long flags;

	bool need_halt_and_tlb =

		smmu->options & ARM_SMMU_OPT_HALT_AND_TLB_ON_ATOS;
@@ -1956,7 +1955,7 @@ static phys_addr_t arm_smmu_iova_to_phys_hard(struct iommu_domain *domain, 


	cb_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, cfg->cbndx);



	spin_lock_irqsave(&smmu->atos_lock, flags);

	mutex_lock(&smmu->atos_lock);



	if (need_halt_and_tlb) {

		if (arm_smmu_halt(smmu))
@@ -1985,7 +1984,7 @@ static phys_addr_t arm_smmu_iova_to_phys_hard(struct iommu_domain *domain, 
	if (need_halt_and_tlb)

		arm_smmu_resume(smmu);



	spin_unlock_irqrestore(&smmu->atos_lock, flags);

	mutex_unlock(&smmu->atos_lock);



	if (phys & CB_PAR_F) {

		dev_err(dev, "translation fault on %s!\n", dev_name(dev));
@@ -2002,7 +2001,7 @@ err_resume: 
	if (need_halt_and_tlb)

		arm_smmu_resume(smmu);

err_unlock:

	spin_unlock_irqrestore(&smmu->atos_lock, flags);

	mutex_unlock(&smmu->atos_lock);

	arm_smmu_disable_clocks(smmu);

	phys = arm_smmu_iova_to_phys_soft(domain, iova);

	dev_err(dev,
@@ -2549,7 +2548,7 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev) 
	}

	smmu->dev = dev;

	mutex_init(&smmu->attach_lock);

	spin_lock_init(&smmu->atos_lock);

	mutex_init(&smmu->atos_lock);



	of_id = of_match_node(arm_smmu_of_match, dev->of_node);

	smmu->version = (enum arm_smmu_arch_version)of_id->data;