6.6-stable review patch. If anyone has any objections, please let me know.
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From: Eugene Koira eugkoira@amazon.com
commit dce043c07ca1ac19cfbe2844a6dc71e35c322353 upstream.
switch_to_super_page() assumes the memory range it's working on is aligned to the target large page level. Unfortunately, __domain_mapping() doesn't take this into account when using it, and will pass unaligned ranges ultimately freeing a PTE range larger than expected.
Take for example a mapping with the following iov_pfn range [0x3fe400, 0x4c0600), which should be backed by the following mappings:
iov_pfn [0x3fe400, 0x3fffff] covered by 2MiB pages iov_pfn [0x400000, 0x4bffff] covered by 1GiB pages iov_pfn [0x4c0000, 0x4c05ff] covered by 2MiB pages
Under this circumstance, __domain_mapping() will pass [0x400000, 0x4c05ff] to switch_to_super_page() at a 1 GiB granularity, which will in turn free PTEs all the way to iov_pfn 0x4fffff.
Mitigate this by rounding down the iov_pfn range passed to switch_to_super_page() in __domain_mapping() to the target large page level.
Additionally add range alignment checks to switch_to_super_page.
Fixes: 9906b9352a35 ("iommu/vt-d: Avoid duplicate removing in __domain_mapping()") Signed-off-by: Eugene Koira eugkoira@amazon.com Cc: stable@vger.kernel.org Reviewed-by: Nicolas Saenz Julienne nsaenz@amazon.com Reviewed-by: David Woodhouse dwmw@amazon.co.uk Link: https://lore.kernel.org/r/20250826143816.38686-1-eugkoira@amazon.com Signed-off-by: Lu Baolu baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel joerg.roedel@amd.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iommu/intel/iommu.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -2168,6 +2168,10 @@ static void switch_to_super_page(struct struct dma_pte *pte = NULL; unsigned long i;
+ if (WARN_ON(!IS_ALIGNED(start_pfn, lvl_pages) || + !IS_ALIGNED(end_pfn + 1, lvl_pages))) + return; + while (start_pfn <= end_pfn) { if (!pte) pte = pfn_to_dma_pte(domain, start_pfn, &level, @@ -2241,7 +2245,8 @@ __domain_mapping(struct dmar_domain *dom unsigned long pages_to_remove;
pteval |= DMA_PTE_LARGE_PAGE; - pages_to_remove = min_t(unsigned long, nr_pages, + pages_to_remove = min_t(unsigned long, + round_down(nr_pages, lvl_pages), nr_pte_to_next_page(pte) * lvl_pages); end_pfn = iov_pfn + pages_to_remove - 1; switch_to_super_page(domain, iov_pfn, end_pfn, largepage_lvl);