On Thu, 4 Jun 2026 14:09:42 +0530 "Aneesh Kumar K.V (Arm)" <[email protected]> wrote:
> Propagate force_dma_unencrypted() into DMA_ATTR_CC_SHARED in the > dma-direct allocation path and use the attribute to drive the related > decisions. > > This updates dma_direct_alloc(), dma_direct_free(), and > dma_direct_alloc_pages() to fold the forced unencrypted case into attrs. > > Tested-by: Jiri Pirko <[email protected]> > Tested-by: Michael Kelley <[email protected]> > Tested-by: Mostafa Saleh <[email protected]> > Signed-off-by: Aneesh Kumar K.V (Arm) <[email protected]> Reviewed-by: Petr Tesarik <[email protected]> Petr T > --- > kernel/dma/direct.c | 53 +++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 44 insertions(+), 9 deletions(-) > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index a741c8a2ee66..90dc5057a0c0 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -193,16 +193,31 @@ void *dma_direct_alloc(struct device *dev, size_t size, > dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) > { > bool remap = false, set_uncached = false; > - bool mark_mem_decrypt = true; > + bool mark_mem_decrypt = false; > struct page *page; > void *ret; > > + /* > + * DMA_ATTR_CC_SHARED is not a caller-visible dma_alloc_*() > + * attribute. The direct allocator uses it internally after it has > + * decided that the backing pages must be shared/decrypted, so the > + * rest of the allocation path can consistently select DMA addresses, > + * choose compatible pools and restore encryption on free. > + */ > + if (attrs & DMA_ATTR_CC_SHARED) > + return NULL; > + > + if (force_dma_unencrypted(dev)) { > + attrs |= DMA_ATTR_CC_SHARED; > + mark_mem_decrypt = true; > + } > + > size = PAGE_ALIGN(size); > if (attrs & DMA_ATTR_NO_WARN) > gfp |= __GFP_NOWARN; > > - if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) && > - !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) > + if (((attrs & (DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_CC_SHARED)) == > + DMA_ATTR_NO_KERNEL_MAPPING) && !is_swiotlb_for_alloc(dev)) > return dma_direct_alloc_no_mapping(dev, size, dma_handle, gfp); > > if (!dev_is_dma_coherent(dev)) { > @@ -236,7 +251,7 @@ void *dma_direct_alloc(struct device *dev, size_t size, > * Remapping or decrypting memory may block, allocate the memory from > * the atomic pools instead if we aren't allowed block. > */ > - if ((remap || force_dma_unencrypted(dev)) && > + if ((remap || (attrs & DMA_ATTR_CC_SHARED)) && > dma_direct_use_pool(dev, gfp)) > return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp); > > @@ -312,12 +327,24 @@ void dma_direct_free(struct device *dev, size_t size, > void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs) > { > phys_addr_t phys; > - bool mark_mem_encrypted = true; > + bool mark_mem_encrypted = false; > struct io_tlb_pool *swiotlb_pool; > unsigned int page_order = get_order(size); > > - if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) && > - !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) { > + /* see dma_direct_alloc() for details */ > + WARN_ON(attrs & DMA_ATTR_CC_SHARED); > + > + /* > + * if the device had requested for an unencrypted buffer, > + * convert it to encrypted on free > + */ > + if (force_dma_unencrypted(dev)) { > + attrs |= DMA_ATTR_CC_SHARED; > + mark_mem_encrypted = true; > + } > + > + if (((attrs & (DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_CC_SHARED)) == > + DMA_ATTR_NO_KERNEL_MAPPING) && !is_swiotlb_for_alloc(dev)) { > /* cpu_addr is a struct page cookie, not a kernel address */ > dma_free_contiguous(dev, cpu_addr, size); > return; > @@ -366,10 +393,14 @@ void dma_direct_free(struct device *dev, size_t size, > struct page *dma_direct_alloc_pages(struct device *dev, size_t size, > dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp) > { > + unsigned long attrs = 0; > struct page *page; > void *ret; > > - if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp)) > + if (force_dma_unencrypted(dev)) > + attrs |= DMA_ATTR_CC_SHARED; > + > + if ((attrs & DMA_ATTR_CC_SHARED) && dma_direct_use_pool(dev, gfp)) > return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp); > > if (is_swiotlb_for_alloc(dev)) { > @@ -403,7 +434,11 @@ void dma_direct_free_pages(struct device *dev, size_t > size, > phys_addr_t phys; > void *vaddr = page_address(page); > struct io_tlb_pool *swiotlb_pool; > - bool mark_mem_encrypted = true; > + /* > + * if the device had requested for an unencrypted buffer, > + * convert it to encrypted on free > + */ > + bool mark_mem_encrypted = force_dma_unencrypted(dev); > > /* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */ > if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
