iommu/arm-smmu-v3: Remove io-pgtable spinlock

As for SMMUv2, take advantage of io-pgtable's newfound tolerance for
concurrency. Unfortunately in this case the command queue lock remains a
point of serialisation for the unmap path, but there may be a little
more we can do to ameliorate that in future.

Signed-off-by: Robin Murphy <robin.murphy@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 d50c8d4b9af9f400b0d15004598d278c0d3cd750..884b1a49a52a24b87dc548dce3122ce2fd687c6d 100644 (file)
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -646,7 +646,6 @@ struct arm_smmu_domain {
        struct mutex                    init_mutex; /* Protects smmu pointer */
 
        struct io_pgtable_ops           *pgtbl_ops;
-       spinlock_t                      pgtbl_lock;
 
        enum arm_smmu_domain_stage      stage;
        union {
@@ -1414,7 +1413,6 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
        }
 
        mutex_init(&smmu_domain->init_mutex);
-       spin_lock_init(&smmu_domain->pgtbl_lock);
        return &smmu_domain->domain;
 }
 
@@ -1686,44 +1684,29 @@ out_unlock:
 static int arm_smmu_map(struct iommu_domain *domain, unsigned long iova,
                        phys_addr_t paddr, size_t size, int prot)
 {
-       int ret;
-       unsigned long flags;
-       struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
-       struct io_pgtable_ops *ops = smmu_domain->pgtbl_ops;
+       struct io_pgtable_ops *ops = to_smmu_domain(domain)->pgtbl_ops;
 
        if (!ops)
                return -ENODEV;
 
-       spin_lock_irqsave(&smmu_domain->pgtbl_lock, flags);
-       ret = ops->map(ops, iova, paddr, size, prot);
-       spin_unlock_irqrestore(&smmu_domain->pgtbl_lock, flags);
-       return ret;
+       return ops->map(ops, iova, paddr, size, prot);
 }
 
 static size_t
 arm_smmu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
 {
-       size_t ret;
-       unsigned long flags;
-       struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
-       struct io_pgtable_ops *ops = smmu_domain->pgtbl_ops;
+       struct io_pgtable_ops *ops = to_smmu_domain(domain)->pgtbl_ops;
 
        if (!ops)
                return 0;
 
-       spin_lock_irqsave(&smmu_domain->pgtbl_lock, flags);
-       ret = ops->unmap(ops, iova, size);
-       spin_unlock_irqrestore(&smmu_domain->pgtbl_lock, flags);
-       return ret;
+       return ops->unmap(ops, iova, size);
 }
 
 static phys_addr_t
 arm_smmu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova)
 {
-       phys_addr_t ret;
-       unsigned long flags;
-       struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
-       struct io_pgtable_ops *ops = smmu_domain->pgtbl_ops;
+       struct io_pgtable_ops *ops = to_smmu_domain(domain)->pgtbl_ops;
 
        if (domain->type == IOMMU_DOMAIN_IDENTITY)
                return iova;
@@ -1731,11 +1714,7 @@ arm_smmu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova)
        if (!ops)
                return 0;
 
-       spin_lock_irqsave(&smmu_domain->pgtbl_lock, flags);
-       ret = ops->iova_to_phys(ops, iova);
-       spin_unlock_irqrestore(&smmu_domain->pgtbl_lock, flags);
-
-       return ret;
+       return ops->iova_to_phys(ops, iova);
 }
 
 static struct platform_driver arm_smmu_driver;