Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a44a9791 authored by Will Deacon's avatar Will Deacon
Browse files

iommu/arm-smmu: use mutex instead of spinlock for locking page tables 



When creating IO mappings, we lazily allocate our page tables using the
standard, non-atomic allocator functions. This presents us with a
problem, since our page tables are protected with a spinlock.

This patch reworks the smmu_domain lock to use a mutex instead of a
spinlock. iova_to_phys is then reworked so that it only reads the page
tables, and can run in a lockless fashion, leaving the mutex to guard
against concurrent mapping threads.

Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent dc1ccc48

drivers/iommu/arm-smmu.c

+26 −36
Original line number Diff line number Diff line
@@ -392,7 +392,7 @@ struct arm_smmu_domain { 
	struct arm_smmu_cfg		root_cfg;

	phys_addr_t			output_mask;



	spinlock_t			lock;

	struct mutex			lock;

};



static DEFINE_SPINLOCK(arm_smmu_devices_lock);
@@ -900,7 +900,7 @@ static int arm_smmu_domain_init(struct iommu_domain *domain) 
		goto out_free_domain;

	smmu_domain->root_cfg.pgd = pgd;



	spin_lock_init(&smmu_domain->lock);

	mutex_init(&smmu_domain->lock);

	domain->priv = smmu_domain;

	return 0;
@@ -1137,7 +1137,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) 
	 * Sanity check the domain. We don't currently support domains

	 * that cross between different SMMU chains.

	 */

	spin_lock(&smmu_domain->lock);

	mutex_lock(&smmu_domain->lock);

	if (!smmu_domain->leaf_smmu) {

		/* Now that we have a master, we can finalise the domain */

		ret = arm_smmu_init_domain_context(domain, dev);
@@ -1152,7 +1152,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) 
			dev_name(device_smmu->dev));

		goto err_unlock;

	}

	spin_unlock(&smmu_domain->lock);

	mutex_unlock(&smmu_domain->lock);



	/* Looks ok, so add the device to the domain */

	master = find_smmu_master(smmu_domain->leaf_smmu, dev->of_node);
@@ -1162,7 +1162,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) 
	return arm_smmu_domain_add_master(smmu_domain, master);



err_unlock:

	spin_unlock(&smmu_domain->lock);

	mutex_unlock(&smmu_domain->lock);

	return ret;

}
@@ -1394,7 +1394,7 @@ static int arm_smmu_handle_mapping(struct arm_smmu_domain *smmu_domain, 
	if (paddr & ~output_mask)

		return -ERANGE;



	spin_lock(&smmu_domain->lock);

	mutex_lock(&smmu_domain->lock);

	pgd += pgd_index(iova);

	end = iova + size;

	do {
@@ -1410,7 +1410,7 @@ static int arm_smmu_handle_mapping(struct arm_smmu_domain *smmu_domain, 
	} while (pgd++, iova != end);



out_unlock:

	spin_unlock(&smmu_domain->lock);

	mutex_unlock(&smmu_domain->lock);



	/* Ensure new page tables are visible to the hardware walker */

	if (smmu->features & ARM_SMMU_FEAT_COHERENT_WALK)
@@ -1449,44 +1449,34 @@ static size_t arm_smmu_unmap(struct iommu_domain *domain, unsigned long iova, 
static phys_addr_t arm_smmu_iova_to_phys(struct iommu_domain *domain,

					 dma_addr_t iova)

{

	pgd_t *pgd;

	pud_t *pud;

	pmd_t *pmd;

	pte_t *pte;

	pgd_t *pgdp, pgd;

	pud_t pud;

	pmd_t pmd;

	pte_t pte;

	struct arm_smmu_domain *smmu_domain = domain->priv;

	struct arm_smmu_cfg *root_cfg = &smmu_domain->root_cfg;

	struct arm_smmu_device *smmu = root_cfg->smmu;



	spin_lock(&smmu_domain->lock);

	pgd = root_cfg->pgd;

	if (!pgd)

		goto err_unlock;

	pgdp = root_cfg->pgd;

	if (!pgdp)

		return 0;



	pgd += pgd_index(iova);

	if (pgd_none_or_clear_bad(pgd))

		goto err_unlock;

	pgd = *(pgdp + pgd_index(iova));

	if (pgd_none(pgd))

		return 0;



	pud = pud_offset(pgd, iova);

	if (pud_none_or_clear_bad(pud))

		goto err_unlock;

	pud = *pud_offset(&pgd, iova);

	if (pud_none(pud))

		return 0;



	pmd = pmd_offset(pud, iova);

	if (pmd_none_or_clear_bad(pmd))

		goto err_unlock;

	pmd = *pmd_offset(&pud, iova);

	if (pmd_none(pmd))

		return 0;



	pte = pmd_page_vaddr(*pmd) + pte_index(iova);

	pte = *(pmd_page_vaddr(pmd) + pte_index(iova));

	if (pte_none(pte))

		goto err_unlock;



	spin_unlock(&smmu_domain->lock);

	return __pfn_to_phys(pte_pfn(*pte)) | (iova & ~PAGE_MASK);

		return 0;



err_unlock:

	spin_unlock(&smmu_domain->lock);

	dev_warn(smmu->dev,

		 "invalid (corrupt?) page tables detected for iova 0x%llx\n",

		 (unsigned long long)iova);

	return -EINVAL;

	return __pfn_to_phys(pte_pfn(pte)) | (iova & ~PAGE_MASK);

}



static int arm_smmu_domain_has_cap(struct iommu_domain *domain,