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.

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 <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lu Baolu <[e-mail]>
Signed-off-by: Joerg Roedel <[e-mail]>

drivers/iommu/intel/iommu.c

···
 
 /* 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)
 {
···
 
 		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;
 		}
···
 				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;
 		}
···
 				       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) {
···
 	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,