linux-kernel - [PATCH] iommu/vt-d: Fix to convert mm pfn to dma pfn

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Message-Id: <20230625082046.979742-1-yanfei.xu@intel.com>
Date:   Sun, 25 Jun 2023 16:20:46 +0800
From:   Yanfei Xu <yanfei.xu@...el.com>
To:     dwmw2@...radead.org, baolu.lu@...ux.intel.com, joro@...tes.org,
        will@...nel.org, robin.murphy@....com
Cc:     iommu@...ts.linux.dev, linux-kernel@...r.kernel.org,
        yanfei.xu@...el.com
Subject: [PATCH] iommu/vt-d: Fix to convert mm pfn to dma pfn

For the case that VT-d page is smaller than mm page, converting dma
pfn should be handled in two cases which are for start pfn and for
end pfn. Currently the calculation of end dma pfn is incorrect and
the result is less than real page frame number which is causing the
mapping of iova always misses some page frames.

Hence rename the mm_to_dma_pfn() to mm_to_dma_pfn_start() and add
a new helper for converting end dma pfn named mm_to_dma_pfn_end()

Signed-off-by: Yanfei Xu <yanfei.xu@...el.com>
---
Found from reading VT-D codes.

 drivers/iommu/intel/iommu.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 8096273b034c..5ceb12b90c1b 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -113,13 +113,17 @@ static inline unsigned long lvl_to_nr_pages(unsigned int lvl)
 
 /* VT-d pages must always be _smaller_ than MM pages. Otherwise things
    are never going to work. */
-static inline unsigned long mm_to_dma_pfn(unsigned long mm_pfn)
+static inline unsigned long mm_to_dma_pfn_start(unsigned long mm_pfn)
 {
 	return mm_pfn << (PAGE_SHIFT - VTD_PAGE_SHIFT);
 }
+static inline unsigned long mm_to_dma_pfn_end(unsigned long mm_pfn)
+{
+	return ((mm_pfn + 1) << (PAGE_SHIFT - VTD_PAGE_SHIFT)) - 1;
+}
 static inline unsigned long page_to_dma_pfn(struct page *pg)
 {
-	return mm_to_dma_pfn(page_to_pfn(pg));
+	return mm_to_dma_pfn_start(page_to_pfn(pg));
 }
 static inline unsigned long virt_to_dma_pfn(void *p)
 {
@@ -2374,8 +2378,8 @@ static int __init si_domain_init(int hw)
 
 		for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
 			ret = iommu_domain_identity_map(si_domain,
-					mm_to_dma_pfn(start_pfn),
-					mm_to_dma_pfn(end_pfn));
+					mm_to_dma_pfn_start(start_pfn),
+					mm_to_dma_pfn_end(end_pfn));
 			if (ret)
 				return ret;
 		}
@@ -2396,8 +2400,8 @@ static int __init si_domain_init(int hw)
 				continue;
 
 			ret = iommu_domain_identity_map(si_domain,
-					mm_to_dma_pfn(start >> PAGE_SHIFT),
-					mm_to_dma_pfn(end >> PAGE_SHIFT));
+					mm_to_dma_pfn_start(start >> PAGE_SHIFT),
+					mm_to_dma_pfn_end(end >> PAGE_SHIFT));
 			if (ret)
 				return ret;
 		}
@@ -3567,8 +3571,8 @@ static int intel_iommu_memory_notifier(struct notifier_block *nb,
 				       unsigned long val, void *v)
 {
 	struct memory_notify *mhp = v;
-	unsigned long start_vpfn = mm_to_dma_pfn(mhp->start_pfn);
-	unsigned long last_vpfn = mm_to_dma_pfn(mhp->start_pfn +
+	unsigned long start_vpfn = mm_to_dma_pfn_start(mhp->start_pfn);
+	unsigned long last_vpfn = mm_to_dma_pfn_end(mhp->start_pfn +
 			mhp->nr_pages - 1);
 
 	switch (val) {
@@ -4278,7 +4282,7 @@ static void intel_iommu_tlb_sync(struct iommu_domain *domain,
 	unsigned long i;
 
 	nrpages = aligned_nrpages(gather->start, size);
-	start_pfn = mm_to_dma_pfn(iova_pfn);
+	start_pfn = mm_to_dma_pfn_start(iova_pfn);
 
 	xa_for_each(&dmar_domain->iommu_array, i, info)
 		iommu_flush_iotlb_psi(info->iommu, dmar_domain,
-- 
2.34.1