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

Leon Romanovsky posted 8 patches 3 months, 2 weeks ago
There is a newer version of this series
[PATCH 6/8] dma-mapping: fail early if physical address is mapped through platform callback
Posted by Leon Romanovsky 3 months, 2 weeks ago 
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
Re: [PATCH 6/8] dma-mapping: fail early if physical address is mapped through platform callback
Posted by Robin Murphy 2 months, 2 weeks ago 
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.

> 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);
Re: [PATCH 6/8] dma-mapping: fail early if physical address is mapped through platform callback
Posted by Leon Romanovsky 2 months, 1 week ago 
On Fri, Jul 25, 2025 at 09:04:50PM +0100, Robin Murphy wrote:
> 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.

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);
~
~
~

Thanks

Patchew 2.1-devel-b67e4c2

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