From ba2374fd2bf379f933773811fdb06cb6a5445f41 Mon Sep 17 00:00:00 2001 From: Christian Zander Date: Wed, 10 Jun 2015 09:41:45 -0700 Subject: [PATCH] iommu/vt-d: fix range computation when making room for large pages In preparation for the installation of a large page, any small page tables that may still exist in the target IOV address range are removed. However, if a scatter/gather list entry is large enough to fit more than one large page, the address space for any subsequent large pages is not cleared of conflicting small page tables. This can cause legitimate mapping requests to fail with errors of the form below, potentially followed by a series of IOMMU faults: ERROR: DMA PTE for vPFN 0xfde00 already set (to 7f83a4003 not 7e9e00083) In this example, a 4MiB scatter/gather list entry resulted in the successful installation of a large page @ vPFN 0xfdc00, followed by a failed attempt to install another large page @ vPFN 0xfde00, due to the presence of a pointer to a small page table @ 0x7f83a4000. To address this problem, compute the number of large pages that fit into a given scatter/gather list entry, and use it to derive the last vPFN covered by the large page(s). Cc: stable@vger.kernel.org Signed-off-by: Christian Zander Signed-off-by: David Woodhouse --- drivers/iommu/intel-iommu.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 041bc18..df53855 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -2115,15 +2115,19 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn, return -ENOMEM; /* It is large page*/ if (largepage_lvl > 1) { + unsigned long nr_superpages, end_pfn; + pteval |= DMA_PTE_LARGE_PAGE; lvl_pages = lvl_to_nr_pages(largepage_lvl); + + nr_superpages = sg_res / lvl_pages; + end_pfn = iov_pfn + nr_superpages * lvl_pages - 1; + /* * Ensure that old small page tables are - * removed to make room for superpage, - * if they exist. + * removed to make room for superpage(s). */ - dma_pte_free_pagetable(domain, iov_pfn, - iov_pfn + lvl_pages - 1); + dma_pte_free_pagetable(domain, iov_pfn, end_pfn); } else { pteval &= ~(uint64_t)DMA_PTE_LARGE_PAGE; } -- 2.7.4