[PATCH v8 12/14] iommu/vt-d: use iommu_num_sg_pages

[Dan Williams]

Use the common helper for accounting the size of the IOVA range for a
scatterlist so that iommu and dma apis agree on the size of a
scatterlist. This is in support for using iommu_unmap() in advance of
dma_unmap_sg() to invalidate an io-mapping in advance of the IOVA range
being deallocated. MAP_DIRECT needs this functionality for force
revoking RDMA access to a DAX mapping when userspace fails to respond to
within a lease break timeout period.

Cc: Ashok Raj <ashok.raj at intel.com>
Cc: David Woodhouse <dwmw2 at infradead.org>
Cc: Joerg Roedel <joro at 8bytes.org>
Signed-off-by: Dan Williams <dan.j.williams at intel.com>
---
 drivers/iommu/intel-iommu.c |   19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index f3f4939cebad..94a5fbe62fb8 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3785,14 +3785,9 @@ static void intel_unmap_sg(struct device *dev, struct scatterlist *sglist,
 			   unsigned long attrs)
 {
 	dma_addr_t startaddr = sg_dma_address(sglist) & PAGE_MASK;
-	unsigned long nrpages = 0;
-	struct scatterlist *sg;
-	int i;
-
-	for_each_sg(sglist, sg, nelems, i) {
-		nrpages += aligned_nrpages(sg_dma_address(sg), sg_dma_len(sg));
-	}
+	unsigned long nrpages;
 
+	nrpages = iommu_sg_num_pages(dev, sglist, nelems);
 	intel_unmap(dev, startaddr, nrpages << VTD_PAGE_SHIFT);
 }
 
@@ -3813,14 +3808,12 @@ static int intel_nontranslate_map_sg(struct device *hddev,
 static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nelems,
 			enum dma_data_direction dir, unsigned long attrs)
 {
-	int i;
 	struct dmar_domain *domain;
 	size_t size = 0;
 	int prot = 0;
 	unsigned long iova_pfn;
 	int ret;
-	struct scatterlist *sg;
-	unsigned long start_vpfn;
+	unsigned long start_vpfn, npages;
 	struct intel_iommu *iommu;
 
 	BUG_ON(dir == DMA_NONE);
@@ -3833,11 +3826,9 @@ static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nele
 
 	iommu = domain_get_iommu(domain);
 
-	for_each_sg(sglist, sg, nelems, i)
-		size += aligned_nrpages(sg->offset, sg->length);
+	npages = iommu_sg_num_pages(dev, sglist, nelems);
 
-	iova_pfn = intel_alloc_iova(dev, domain, dma_to_mm_pfn(size),
-				*dev->dma_mask);
+	iova_pfn = intel_alloc_iova(dev, domain, npages, *dev->dma_mask);
 	if (!iova_pfn) {
 		sglist->dma_length = 0;
 		return 0;