linux-kernel - [PATCH v7 08/15] iommu: Add support for the map

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Date:   Wed, 16 Jun 2021 06:38:49 -0700
From:   Georgi Djakov <quic_c_gdjako@...cinc.com>
To:     <will@...nel.org>, <robin.murphy@....com>
CC:     <joro@...tes.org>, <isaacm@...eaurora.org>,
        <baolu.lu@...ux.intel.com>, <pratikp@...eaurora.org>,
        <iommu@...ts.linux-foundation.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <djakov@...nel.org>
Subject: [PATCH v7 08/15] iommu: Add support for the map_pages() callback

From: "Isaac J. Manjarres" <isaacm@...eaurora.org>

Since iommu_pgsize can calculate how many pages of the
same size can be mapped/unmapped before the next largest
page size boundary, add support for invoking an IOMMU
driver's map_pages() callback, if it provides one.

Signed-off-by: Isaac J. Manjarres <isaacm@...eaurora.org>
Suggested-by: Will Deacon <will@...nel.org>
Signed-off-by: Georgi Djakov <quic_c_gdjako@...cinc.com>
---
 drivers/iommu/iommu.c | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 725622c7e603..70a729ce88b1 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2429,6 +2429,30 @@ static size_t iommu_pgsize(struct iommu_domain *domain, unsigned long iova,
 	return pgsize;
 }
 
+static int __iommu_map_pages(struct iommu_domain *domain, unsigned long iova,
+			     phys_addr_t paddr, size_t size, int prot,
+			     gfp_t gfp, size_t *mapped)
+{
+	const struct iommu_ops *ops = domain->ops;
+	size_t pgsize, count;
+	int ret;
+
+	pgsize = iommu_pgsize(domain, iova, paddr, size, &count);
+
+	pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx count %zu\n",
+		 iova, &paddr, pgsize, count);
+
+	if (ops->map_pages) {
+		ret = ops->map_pages(domain, iova, paddr, pgsize, count, prot,
+				     gfp, mapped);
+	} else {
+		ret = ops->map(domain, iova, paddr, pgsize, prot, gfp);
+		*mapped = ret ? 0 : pgsize;
+	}
+
+	return ret;
+}
+
 static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
 		       phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
 {
@@ -2439,7 +2463,7 @@ static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
 	phys_addr_t orig_paddr = paddr;
 	int ret = 0;
 
-	if (unlikely(ops->map == NULL ||
+	if (unlikely(!(ops->map || ops->map_pages) ||
 		     domain->pgsize_bitmap == 0UL))
 		return -ENODEV;
 
@@ -2463,18 +2487,21 @@ 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, NULL);
+		size_t mapped = 0;
 
-		pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx\n",
-			 iova, &paddr, pgsize);
-		ret = ops->map(domain, iova, paddr, pgsize, prot, gfp);
+		ret = __iommu_map_pages(domain, iova, paddr, size, prot, gfp,
+					&mapped);
+		/*
+		 * Some pages may have been mapped, even if an error occurred,
+		 * so we should account for those so they can be unmapped.
+		 */
+		size -= mapped;
 
 		if (ret)
 			break;
 
-		iova += pgsize;
-		paddr += pgsize;
-		size -= pgsize;
+		iova += mapped;
+		paddr += mapped;
 	}
 
 	/* unroll mapping in case something went wrong */