Re: [PATCH 6/8] dma-mapping: fail early if physical address is mapped through platform callback
From: Robin Murphy <robin.murphy@arm.com>
Date: 2025-07-25 20:04:59
Also in:
linux-doc, linux-iommu, linux-mm, linuxppc-dev, lkml, virtualization
On 2025-06-25 2:19 pm, Leon Romanovsky wrote:
From: Leon Romanovsky <leonro@nvidia.com> All platforms which implement map_page interface don't support physical addresses without real struct page. Add condition to check it.
As-is, the condition also needs to cover iommu-dma, because that also still doesn't support non-page-backed addresses. You can't just do a simple s/page/phys/ rename and hope it's OK because you happen to get away with it for coherent, 64-bit, trusted devices. Thanks, Robin.
quoted hunk ↗ jump to hunk
Signed-off-by: Leon Romanovsky <leonro@nvidia.com> --- kernel/dma/mapping.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 709405d46b2b..74efb6909103 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c@@ -158,6 +158,7 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page, { const struct dma_map_ops *ops = get_dma_ops(dev); phys_addr_t phys = page_to_phys(page) + offset; + bool is_pfn_valid = true; dma_addr_t addr; BUG_ON(!valid_dma_direction(dir));@@ -170,8 +171,20 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page, addr = dma_direct_map_phys(dev, phys, size, dir, attrs); else if (use_dma_iommu(dev)) addr = iommu_dma_map_phys(dev, phys, size, dir, attrs); - else + else { + if (IS_ENABLED(CONFIG_DMA_API_DEBUG)) + is_pfn_valid = pfn_valid(PHYS_PFN(phys)); + + if (unlikely(!is_pfn_valid)) + return DMA_MAPPING_ERROR; + + /* + * All platforms which implement .map_page() don't support + * non-struct page backed addresses. + */ addr = ops->map_page(dev, page, offset, size, dir, attrs); + } + kmsan_handle_dma(phys, size, dir); trace_dma_map_phys(dev, phys, addr, size, dir, attrs); debug_dma_map_phys(dev, phys, size, dir, addr, attrs);