[RFC PATCH 3/5] iommu: Add support for the unmap_pages IOMMU callback

["Isaac J. Manjarres" <isaacm@codeaurora.org>]

The IOMMU framework currently unmaps memory one page block at a time,
per the page block sizes that are supported by the IOMMU hardware.
Now that IOMMU drivers can supply a callback for unmapping multiple
in one call, add support in the IOMMU framework to calculate how many
page mappings of the same size can be unmapped in one shot, and invoke the
IOMMU driver's unmap_pages callback if it has one. Otherwise, the
existing behavior will be used.

Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
Suggested-by: Will Deacon <will@kernel.org>
---
 drivers/iommu/iommu.c | 44 +++++++++++++++++++++++++++++++++++++------
 1 file changed, 38 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index d0b0a15dba84..dc4295f6bc7f 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2356,8 +2356,8 @@ phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova)
 }
 EXPORT_SYMBOL_GPL(iommu_iova_to_phys);
 
-static size_t iommu_pgsize(struct iommu_domain *domain,
-			   unsigned long addr_merge, size_t size)
+static size_t __iommu_pgsize(struct iommu_domain *domain,
+			     unsigned long addr_merge, size_t size)
 {
 	unsigned int pgsize_idx;
 	size_t pgsize;
@@ -2388,6 +2388,24 @@ static size_t iommu_pgsize(struct iommu_domain *domain,
 	return pgsize;
 }
 
+static size_t iommu_pgsize(struct iommu_domain *domain,
+			   unsigned long addr_merge, size_t size,
+			   size_t *pgcount)
+{
+	size_t pgsize = __iommu_pgsize(domain, addr_merge, size);
+	size_t pgs = 0;
+
+	do {
+		pgs++;
+		size -= pgsize;
+		addr_merge += pgsize;
+	} while (size && __iommu_pgsize(domain, addr_merge, size) == pgsize);
+
+	*pgcount = pgs;
+
+	return pgsize;
+}
+
 static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
 		       phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
 {
@@ -2422,7 +2440,7 @@ static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
 	pr_debug("map: iova 0x%lx pa %pa size 0x%zx\n", iova, &paddr, size);
 
 	while (size) {
-		size_t pgsize = iommu_pgsize(domain, iova | paddr, size);
+		size_t pgsize = __iommu_pgsize(domain, iova | paddr, size);
 
 		pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx\n",
 			 iova, &paddr, pgsize);
@@ -2473,6 +2491,21 @@ int iommu_map_atomic(struct iommu_domain *domain, unsigned long iova,
 }
 EXPORT_SYMBOL_GPL(iommu_map_atomic);
 
+static size_t __iommu_unmap_pages(struct iommu_domain *domain, unsigned long iova,
+				  size_t size, struct iommu_iotlb_gather *iotlb_gather)
+{
+	const struct iommu_ops *ops = domain->ops;
+	size_t pgsize, pgcount;
+
+	if (ops->unmap_pages) {
+		pgsize = iommu_pgsize(domain, iova, size, &pgcount);
+		return ops->unmap_pages(domain, iova, pgsize, pgcount, iotlb_gather);
+	}
+
+	pgsize = __iommu_pgsize(domain, iova, size);
+	return ops->unmap(domain, iova, pgsize, iotlb_gather);
+}
+
 static size_t __iommu_unmap(struct iommu_domain *domain,
 			    unsigned long iova, size_t size,
 			    struct iommu_iotlb_gather *iotlb_gather)
@@ -2510,9 +2543,8 @@ static size_t __iommu_unmap(struct iommu_domain *domain,
 	 * or we hit an area that isn't mapped.
 	 */
 	while (unmapped < size) {
-		size_t pgsize = iommu_pgsize(domain, iova, size - unmapped);
-
-		unmapped_page = ops->unmap(domain, iova, pgsize, iotlb_gather);
+		unmapped_page = __iommu_unmap_pages(domain, iova, size - unmapped,
+						    iotlb_gather);
 		if (!unmapped_page)
 			break;
 
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

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