Re: [PATCH 6/8] dma-mapping: fail early if physical address is mapped through platform callback
From: Leon Romanovsky <leon@kernel.org>
Date: 2025-07-27 06:30:32
Also in:
linux-doc, linux-iommu, linux-mm, linux-trace-kernel, lkml, virtualization
Subsystem:
dma mapping helpers, the rest · Maintainers:
Marek Szyprowski, Linus Torvalds
On Fri, Jul 25, 2025 at 09:04:50PM +0100, Robin Murphy wrote:
On 2025-06-25 2:19 pm, Leon Romanovsky wrote:quoted
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.
It needs to be follow up patch. Is this what you envision?
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index e1586eb52ab34..31214fde88124 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c@@ -167,6 +167,12 @@ dma_addr_t dma_map_phys(struct device *dev, phys_addr_t phys, size_t size, arch_dma_map_phys_direct(dev, phys + size)) addr = dma_direct_map_phys(dev, phys, size, dir, attrs); else if (use_dma_iommu(dev)) + if (IS_ENABLED(CONFIG_DMA_API_DEBUG) && + !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) + is_pfn_valid = pfn_valid(PHYS_PFN(phys)); + + if (unlikely(!is_pfn_valid)) + return DMA_MAPPING_ERROR; addr = iommu_dma_map_phys(dev, phys, size, dir, attrs); else { struct page *page = phys_to_page(phys);
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