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Fri, 22 May 2026 04:29:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779424153; bh=XzNUfuSsVIAYZs66SuzTocA+H2G8cNxm1JUvnlC50Gw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=igaRhG3Fk+QrZB5QIMIHo9UEo10rvWO62VQbeVrlG+1DKAlRtl7YvtV/YorKdk/SR QjdGSX4OLX4hNF2YRB0PfJqJzkI3jcZDR76lUz9I+EAQxWWSc3ykJmTVf4+1AXMjlz IVDuroWAsA4x+wlSsDe29o4KhwOHghD3wC8Etc90wcyVVPX8kEeokLxzXOMVt95pGG sW2oH4ydn6pS5UlUa0gza6XErSSZBCjGnO1IGX7EGBFDgPHUQHAIprsdCbSfCEW6lx 9S3RUM0vSUPddF7CBrslgvxePZvSZNcotzES+bYz0szlIIUFIGVfLZBwQl5UZTcEis +6KmxV0iynWXA== From: "Aneesh Kumar K.V (Arm)" To: iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev Cc: "Aneesh Kumar K.V (Arm)" , Robin Murphy , Marek Szyprowski , Will Deacon , Marc Zyngier , Steven Price , Suzuki K Poulose , Catalin Marinas , Jiri Pirko , Jason Gunthorpe , Mostafa Saleh , Petr Tesarik , Alexey Kardashevskiy , Dan Williams , Xu Yilun , linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , x86@kernel.org, Jiri Pirko Subject: [PATCH v5 03/20] dma-direct: swiotlb: handle swiotlb alloc/free outside __dma_direct_alloc_pages Date: Fri, 22 May 2026 09:57:58 +0530 Message-ID: <20260522042815.370873-4-aneesh.kumar@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260522042815.370873-1-aneesh.kumar@kernel.org> References: <20260522042815.370873-1-aneesh.kumar@kernel.org> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Move swiotlb allocation out of __dma_direct_alloc_pages() and handle it in dma_direct_alloc() / dma_direct_alloc_pages(). This is needed for follow-up changes that simplify the handling of memory encryption/decryption based on the DMA attribute flags. swiotlb backing pages are already mapped decrypted by swiotlb_update_mem_attributes() and rmem_swiotlb_device_init(), so dma-direct should not call dma_set_decrypted() on allocation nor dma_set_encrypted() on free for swiotlb-backed memory. Update alloc/free paths to detect swiotlb-backed pages and skip encrypt/decrypt transitions for those paths. Keep the existing highmem rejection in dma_direct_alloc_pages() for swiotlb allocations. Only for "restricted-dma-pool", we currently set `for_alloc = true`, while rmem_swiotlb_device_init() decrypts the whole pool up front. This pool is typically used together with "shared-dma-pool", where the shared region is accessed after remap/ioremap and the returned address is suitable for decrypted memory access. So existing code paths remain valid. Tested-by: Jiri Pirko Signed-off-by: Aneesh Kumar K.V (Arm) --- include/linux/swiotlb.h | 6 ++++ kernel/dma/direct.c | 71 ++++++++++++++++++++++++++++++----------- kernel/dma/swiotlb.c | 6 ++++ 3 files changed, 65 insertions(+), 18 deletions(-) diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 3dae0f592063..133bb8ca9032 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -284,6 +284,8 @@ extern void swiotlb_print_info(void); #ifdef CONFIG_DMA_RESTRICTED_POOL struct page *swiotlb_alloc(struct device *dev, size_t size); bool swiotlb_free(struct device *dev, struct page *page, size_t size); +void swiotlb_free_from_pool(struct device *dev, phys_addr_t tlb_addr, + size_t size, struct io_tlb_pool *pool); static inline bool is_swiotlb_for_alloc(struct device *dev) { @@ -299,6 +301,10 @@ static inline bool swiotlb_free(struct device *dev, struct page *page, { return false; } +static inline void swiotlb_free_from_pool(struct device *dev, phys_addr_t tlb_addr, + size_t size, struct io_tlb_pool *pool) +{ +} static inline bool is_swiotlb_for_alloc(struct device *dev) { return false; diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index ec887f443741..fe8e83a36058 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -96,14 +96,6 @@ static int dma_set_encrypted(struct device *dev, void *vaddr, size_t size) return ret; } -static void __dma_direct_free_pages(struct device *dev, struct page *page, - size_t size) -{ - if (swiotlb_free(dev, page, size)) - return; - dma_free_contiguous(dev, page, size); -} - static struct page *dma_direct_alloc_swiotlb(struct device *dev, size_t size) { struct page *page = swiotlb_alloc(dev, size); @@ -125,9 +117,6 @@ static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size, WARN_ON_ONCE(!PAGE_ALIGNED(size)); - if (is_swiotlb_for_alloc(dev)) - return dma_direct_alloc_swiotlb(dev, size); - gfp |= dma_direct_optimal_gfp_mask(dev, &phys_limit); page = dma_alloc_contiguous(dev, size, gfp); if (page) { @@ -204,6 +193,7 @@ 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; struct page *page; void *ret; @@ -250,11 +240,21 @@ void *dma_direct_alloc(struct device *dev, size_t size, dma_direct_use_pool(dev, gfp)) return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp); + if (is_swiotlb_for_alloc(dev)) { + page = dma_direct_alloc_swiotlb(dev, size); + if (page) { + mark_mem_decrypt = false; + goto setup_page; + } + return NULL; + } + /* we always manually zero the memory once we are done */ page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, true); if (!page) return NULL; +setup_page: /* * dma_alloc_contiguous can return highmem pages depending on a * combination the cma= arguments and per-arch setup. These need to be @@ -281,7 +281,7 @@ void *dma_direct_alloc(struct device *dev, size_t size, goto out_free_pages; } else { ret = page_address(page); - if (dma_set_decrypted(dev, ret, size)) + if (mark_mem_decrypt && dma_set_decrypted(dev, ret, size)) goto out_leak_pages; } @@ -298,10 +298,11 @@ void *dma_direct_alloc(struct device *dev, size_t size, return ret; out_encrypt_pages: - if (dma_set_encrypted(dev, page_address(page), size)) + if (mark_mem_decrypt && dma_set_encrypted(dev, page_address(page), size)) return NULL; out_free_pages: - __dma_direct_free_pages(dev, page, size); + if (!swiotlb_free(dev, page, size)) + dma_free_contiguous(dev, page, size); return NULL; out_leak_pages: return NULL; @@ -310,6 +311,9 @@ void *dma_direct_alloc(struct device *dev, size_t size, 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; + struct io_tlb_pool *swiotlb_pool; unsigned int page_order = get_order(size); if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) && @@ -338,16 +342,25 @@ void dma_direct_free(struct device *dev, size_t size, dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size))) return; + phys = dma_to_phys(dev, dma_addr); + swiotlb_pool = swiotlb_find_pool(dev, phys); + if (swiotlb_pool) + /* Swiotlb doesn't need a page attribute update on free */ + mark_mem_encrypted = false; + if (is_vmalloc_addr(cpu_addr)) { vunmap(cpu_addr); } else { if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED)) arch_dma_clear_uncached(cpu_addr, size); - if (dma_set_encrypted(dev, cpu_addr, size)) + if (mark_mem_encrypted && dma_set_encrypted(dev, cpu_addr, size)) return; } - __dma_direct_free_pages(dev, dma_direct_to_page(dev, dma_addr), size); + if (swiotlb_pool) + swiotlb_free_from_pool(dev, phys, size, swiotlb_pool); + else + dma_free_contiguous(dev, dma_direct_to_page(dev, dma_addr), size); } struct page *dma_direct_alloc_pages(struct device *dev, size_t size, @@ -359,6 +372,15 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size, if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp)) return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp); + if (is_swiotlb_for_alloc(dev)) { + page = dma_direct_alloc_swiotlb(dev, size); + if (!page) + return NULL; + + ret = page_address(page); + goto setup_page; + } + page = __dma_direct_alloc_pages(dev, size, gfp, false); if (!page) return NULL; @@ -366,6 +388,7 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size, ret = page_address(page); if (dma_set_decrypted(dev, ret, size)) goto out_leak_pages; +setup_page: memset(ret, 0, size); *dma_handle = phys_to_dma_direct(dev, page_to_phys(page)); return page; @@ -377,16 +400,28 @@ void dma_direct_free_pages(struct device *dev, size_t size, struct page *page, dma_addr_t dma_addr, enum dma_data_direction dir) { + phys_addr_t phys; void *vaddr = page_address(page); + struct io_tlb_pool *swiotlb_pool; + bool mark_mem_encrypted = true; /* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */ if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) && dma_free_from_pool(dev, vaddr, size)) return; - if (dma_set_encrypted(dev, vaddr, size)) + phys = page_to_phys(page); + swiotlb_pool = swiotlb_find_pool(dev, phys); + if (swiotlb_pool) + mark_mem_encrypted = false; + + if (mark_mem_encrypted && dma_set_encrypted(dev, vaddr, size)) return; - __dma_direct_free_pages(dev, page, size); + + if (swiotlb_pool) + swiotlb_free_from_pool(dev, phys, size, swiotlb_pool); + else + dma_free_contiguous(dev, page, size); } #if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \ diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 1abd3e6146f4..ac03a6856c2e 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -1809,6 +1809,12 @@ bool swiotlb_free(struct device *dev, struct page *page, size_t size) return true; } +void swiotlb_free_from_pool(struct device *dev, phys_addr_t tlb_addr, size_t size, + struct io_tlb_pool *pool) +{ + swiotlb_release_slots(dev, tlb_addr, pool); +} + static int rmem_swiotlb_device_init(struct reserved_mem *rmem, struct device *dev) { -- 2.43.0