[PATCH 6/8] dma-mapping: fail early if physical address is mapped through platform callback

[Leon Romanovsky <leon@kernel.org>]

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.

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);
-- 
2.49.0