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iommu/arm-smmu: convert atos spinlock to a mutex

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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: Mitchel Humpherys <mitchelh@codeaurora.org>
This commit is contained in:
Mitchel Humpherys 2015-03-13 16:55:23 -07:00 • committed by David Keitel
parent 9c66ec1477
commit 7ed677cb8e
1 changed files with 5 additions and 6 deletions
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11
drivers/iommu/arm-smmu.c
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@ -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;