From: Mostafa Saleh <smostafa@google•com>
To: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel•org>
Cc: iommu@lists•linux.dev, linux-arm-kernel@lists•infradead.org,
linux-kernel@vger•kernel.org, linux-coco@lists•linux.dev,
Robin Murphy <robin.murphy@arm•com>,
Marek Szyprowski <m.szyprowski@samsung•com>,
Will Deacon <will@kernel•org>, Marc Zyngier <maz@kernel•org>,
Steven Price <steven.price@arm•com>,
Suzuki K Poulose <Suzuki.Poulose@arm•com>,
Catalin Marinas <catalin.marinas@arm•com>,
Jiri Pirko <jiri@resnulli•us>, Jason Gunthorpe <jgg@ziepe•ca>,
Petr Tesarik <ptesarik@suse•com>,
Alexey Kardashevskiy <aik@amd•com>,
Dan Williams <dan.j.williams@intel•com>,
Xu Yilun <yilun.xu@linux•intel.com>,
linuxppc-dev@lists•ozlabs.org, linux-s390@vger•kernel.org,
Madhavan Srinivasan <maddy@linux•ibm.com>,
Michael Ellerman <mpe@ellerman•id.au>,
Nicholas Piggin <npiggin@gmail•com>,
"Christophe Leroy (CS GROUP)" <chleroy@kernel•org>,
Alexander Gordeev <agordeev@linux•ibm.com>,
Gerald Schaefer <gerald.schaefer@linux•ibm.com>,
Heiko Carstens <hca@linux•ibm.com>,
Vasily Gorbik <gor@linux•ibm.com>,
Christian Borntraeger <borntraeger@linux•ibm.com>,
Sven Schnelle <svens@linux•ibm.com>,
x86@kernel•org
Subject: Re: [PATCH v4 02/13] dma-direct: use DMA_ATTR_CC_SHARED in alloc/free paths
Date: Wed, 13 May 2026 13:58:43 +0000 [thread overview]
Message-ID: <agSDk0QsEM0ZBCTA@google.com> (raw)
In-Reply-To: <20260512090408.794195-3-aneesh.kumar@kernel.org>
On Tue, May 12, 2026 at 02:33:57PM +0530, Aneesh Kumar K.V (Arm) 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.
>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel•org>
> ---
> kernel/dma/direct.c | 44 ++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 36 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index b958f150718a..0c2e1f8436ce 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -201,16 +201,31 @@ 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)) {
> @@ -244,7 +259,7 @@ 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);
>
> @@ -318,11 +333,20 @@ 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)
> {
> - bool mark_mem_encrypted = true;
> + bool mark_mem_encrypted = false;
> unsigned int page_order = get_order(size);
>
> - if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
> - !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) {
> + /*
> + * 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;
> @@ -365,10 +389,14 @@ 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);
What about dma_direct_free_pages()? Nothing inside uses attrs, but
that’s quite similar to dma_direct_alloc_pages()
Also, at this point, shouldn’t this patch also remove
force_dma_unencrypted() calls from dma_set_decrypted() and
dma_set_encrypted()?
Thanks,
Mostafa
>
> if (is_swiotlb_for_alloc(dev)) {
> --
> 2.43.0
>
next prev parent reply other threads:[~2026-05-13 13:59 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-12 9:03 [PATCH v4 00/13] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
2026-05-12 9:03 ` [PATCH v4 01/13] dma-direct: swiotlb: handle swiotlb alloc/free outside __dma_direct_alloc_pages Aneesh Kumar K.V (Arm)
2026-05-13 13:57 ` Mostafa Saleh
2026-05-14 4:54 ` Aneesh Kumar K.V
2026-05-12 9:03 ` [PATCH v4 02/13] dma-direct: use DMA_ATTR_CC_SHARED in alloc/free paths Aneesh Kumar K.V (Arm)
2026-05-13 13:58 ` Mostafa Saleh [this message]
2026-05-14 5:01 ` Aneesh Kumar K.V
2026-05-12 9:03 ` [PATCH v4 03/13] dma-pool: track decrypted atomic pools and select them via attrs Aneesh Kumar K.V (Arm)
2026-05-13 14:00 ` Mostafa Saleh
2026-05-14 7:00 ` Aneesh Kumar K.V
2026-05-14 8:06 ` Mostafa Saleh
2026-05-16 12:53 ` Alexey Kardashevskiy
2026-05-18 8:19 ` Alexey Kardashevskiy
2026-05-18 8:32 ` Aneesh Kumar K.V
2026-05-12 9:03 ` [PATCH v4 04/13] dma: swiotlb: track pool encryption state and honor DMA_ATTR_CC_SHARED Aneesh Kumar K.V (Arm)
2026-05-13 14:27 ` Mostafa Saleh
2026-05-13 17:24 ` Jason Gunthorpe
2026-05-14 6:24 ` Aneesh Kumar K.V
2026-05-14 11:48 ` Mostafa Saleh
2026-05-14 12:35 ` Jason Gunthorpe
[not found] ` <agXfm3mS_M3fvRrN@google.com>
2026-05-15 22:51 ` Jason Gunthorpe
2026-05-19 11:06 ` Mostafa Saleh
2026-05-19 13:39 ` Jason Gunthorpe
2026-05-14 5:54 ` Aneesh Kumar K.V
2026-05-14 12:02 ` Mostafa Saleh
2026-05-14 12:48 ` Aneesh Kumar K.V
2026-05-14 14:21 ` Mostafa Saleh
2026-05-14 14:43 ` Aneesh Kumar K.V
2026-05-19 11:04 ` Mostafa Saleh
2026-05-19 12:27 ` Aneesh Kumar K.V
2026-05-19 15:07 ` Aneesh Kumar K.V
2026-05-19 15:27 ` Jason Gunthorpe
2026-05-19 16:05 ` Aneesh Kumar K.V
2026-05-19 16:11 ` Jason Gunthorpe
2026-05-20 3:57 ` Aneesh Kumar K.V
2026-05-20 13:40 ` Jason Gunthorpe
2026-05-19 13:29 ` Jason Gunthorpe
2026-05-19 13:41 ` Mostafa Saleh
2026-05-19 14:00 ` Aneesh Kumar K.V
2026-05-19 14:04 ` Mostafa Saleh
2026-05-19 14:17 ` Aneesh Kumar K.V
2026-05-19 14:27 ` Mostafa Saleh
2026-05-19 14:37 ` Jason Gunthorpe
2026-05-19 14:35 ` Jason Gunthorpe
2026-05-19 14:45 ` Mostafa Saleh
2026-05-19 14:49 ` Jason Gunthorpe
2026-05-14 14:37 ` Jason Gunthorpe
2026-05-18 8:19 ` Alexey Kardashevskiy
2026-05-21 17:06 ` Mostafa Saleh
2026-05-21 17:20 ` Aneesh Kumar K.V
2026-05-12 9:04 ` [PATCH v4 05/13] dma-mapping: make dma_pgprot() " Aneesh Kumar K.V (Arm)
2026-05-12 9:04 ` [PATCH v4 06/13] dma-direct: pass attrs to dma_capable() for DMA_ATTR_CC_SHARED checks Aneesh Kumar K.V (Arm)
2026-05-12 9:04 ` [PATCH v4 07/13] dma-direct: make dma_direct_map_phys() honor DMA_ATTR_CC_SHARED Aneesh Kumar K.V (Arm)
2026-05-18 10:04 ` Christian Borntraeger
2026-05-21 15:37 ` Aneesh Kumar K.V
2026-05-12 9:04 ` [PATCH v4 08/13] dma-direct: set decrypted flag for remapped DMA allocations Aneesh Kumar K.V (Arm)
2026-05-12 9:04 ` [PATCH v4 09/13] dma-direct: select DMA address encoding from DMA_ATTR_CC_SHARED Aneesh Kumar K.V (Arm)
2026-05-12 9:04 ` [PATCH v4 10/13] dma-pool: fix page leak in atomic_pool_expand() cleanup Aneesh Kumar K.V (Arm)
2026-05-12 9:04 ` [PATCH v4 11/13] dma-direct: rename ret to cpu_addr in alloc helpers Aneesh Kumar K.V (Arm)
2026-05-12 9:04 ` [PATCH v4 12/13] dma-direct: return struct page from dma_direct_alloc_from_pool() Aneesh Kumar K.V (Arm)
2026-05-12 9:04 ` [PATCH v4 13/13] x86/amd-gart: preserve the direct DMA address until GART mapping succeeds Aneesh Kumar K.V (Arm)
2026-05-21 11:54 ` Aneesh Kumar K.V
2026-05-17 6:19 ` [PATCH v4 00/13] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Jiri Pirko
2026-05-18 8:23 ` Aneesh Kumar K.V
2026-05-18 8:34 ` Jiri Pirko
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