From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=210.118.77.11 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793700652; b=Cgei7lPN5+t2dVxhMVZ5/ObK4NMby72cLsVQslL3akBkPsU7EsBXaHP+Ay4w99iaJbmT izLtGx7t1zqsYf+x5byTkcmL5P2v4M1vK3ROcdGTORsfZ0nz/88vetkhPUg+jnryyobFO 90FN2WiHXD1rosnAlNjWhw5StlXqLgXCtMJ0XOiIuZLlOCJ8RFq1jej1hL31I4v5b6AwF U1TbVAxh+ZjA2MTVcmazOw6fTeIop1zTjJLSzKzStS8Q3C922SBBWZ/M6K4h8ZlhgRfml 3ZIAVISEWRwtsFAWkcF8AQ7zqJBk6X4F+OoZkFPyJMgvPk+LNhnnEZ8895KRevlivUg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793700652; h=DMARC-Filter:Received:DKIM-Filter:DKIM-Signature:Received:Received: Message-ID:Date:MIME-Version:User-Agent:Subject:To:Cc: Content-Language:From:In-Reply-To:Content-Transfer-Encoding: X-CMS-MailID:X-Msg-Generator:Content-Type:X-RootMTR:X-EPHeader: X-CMS-RootMailID:References; bh=2miWXckXEf9/8fJq2kLZ6HHXh4pF31ZiQShBy3CvvJQ=; b=0vqA1xsCQdWEOsrE+Y0Ka/3zeI2dCha3WDaMg3XDDIsy253uGufajHOE+VI6fb8Hj7FN j1w9kzQuUkotmQSnleutq+Yl/qJ4ICUoKN9BxLqg7ykYPCO8QRHiDYLcthrG0TpHigsge Yn7vCF4WOD3PgDjev3LAJM2kPqDeEduqTdUdsv923rvm+4M9uILxfOmzOzTcD99KujPGI wHxRrJD6gKlMzZO6j8eK+aBNITbFyegfPCH+RA4mOTb4vkTo+DgAFo985EFZ+yDwXBSSk jkiEo/+wa7VuCuJlu5S/MdnE4IqT2lD3du9MmCnnAG9Z+pZKFCLhbo3EOcV+BKQFJhg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass header.d=samsung.com header.i=@samsung.com header.a=rsa-sha256 header.s=mail20170921 header.b=P6D9rRFE; arc=none smtp.remote-ip=210.118.77.11 Received: from mailout1.w1.samsung.com (mailout1.w1.samsung.com [210.118.77.11]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3CFBB606BF80 for ; Tue, 3 Nov 2026 10:10:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 3CFBB606BF80 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=samsung.com header.i=@samsung.com header.a=rsa-sha256 header.s=mail20170921 header.b=P6D9rRFE Received: from eucas1p2.samsung.com (unknown [182.198.249.207]) by mailout1.w1.samsung.com (KnoxPortal) with ESMTP id 20261103101049euoutp010c615962723e107c0e0d8e6b0ccf6326~kgTy7DldV2803328033euoutp01v for ; Tue, 3 Nov 2026 10:10:49 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout1.w1.samsung.com 20261103101049euoutp010c615962723e107c0e0d8e6b0ccf6326~kgTy7DldV2803328033euoutp01v DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1793700649; bh=2miWXckXEf9/8fJq2kLZ6HHXh4pF31ZiQShBy3CvvJQ=; h=Date:Subject:To:Cc:From:In-Reply-To:References:From; b=P6D9rRFELTCereOoTaTTR2BoDm2AQJAUCJ6qJ5pqGgWyKUfcU21VeGmGdIZI3rjfq 7/2xZdKsbuncpMyFJOdceQBRXZMEY2rZ+aLKUN/oK24x2foISLnuqxqgtwun76h4ML +6ju2atQwwopT1FHXFTchGy8kFEZOXsKRZPom06Y= Received: from eusmtip2.samsung.com (unknown [203.254.199.222]) by eucas1p2.samsung.com (KnoxPortal) with ESMTPA id 20261103101048eucas1p2192952d7ccdf6cee02830269510aca7e~kgTyPtkgV1245512455eucas1p2H; Tue, 3 Nov 2026 10:10:48 +0000 (GMT) Received: from [106.210.134.192] (unknown [106.210.134.192]) by eusmtip2.samsung.com (KnoxPortal) with ESMTPA id 20261103101047eusmtip2f99b012249277f80088899badb6f04af~kgTwxvNxT3115731157eusmtip2h; Tue, 3 Nov 2026 10:10:46 +0000 (GMT) Message-ID: Date: Tue, 3 Nov 2026 11:10:46 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Betterbird (Windows) Subject: Re: [PATCH v2 3/7] dma-mapping: Keep DMA memory private for capable devices To: Nicolin Chen , Jason Gunthorpe , joro@8bytes.org, Will Deacon , Robin Murphy , Catalin Marinas , rafael@kernel.org, Danilo Krummrich , Johan Hovold Cc: Mark Rutland , Greg Kroah-Hartman , Pranjal Shrivastava , Mostafa Saleh , linux-kernel@vger.kernel.org, iommu@lists.linux.dev, driver-core@lists.linux.dev, Sonang Patel , Ankit Agrawal , shameerali.kolothum.thodi@huawei.com Content-Language: en-US From: Marek Szyprowski In-Reply-To: Content-Transfer-Encoding: 8bit X-CMS-MailID: 20261103101048eucas1p2192952d7ccdf6cee02830269510aca7e X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20261103035025eucas1p2e556ed6dee063a472de0102b87fda0e3 X-EPHeader: CA X-CMS-RootMailID: 20261103035025eucas1p2e556ed6dee063a472de0102b87fda0e3 References: On 03.11.2026 04:49, Nicolin Chen wrote: > Architecture code can require devices to use unencrypted memory. This makes > the DMA API use shared memory for coherent allocations and bounce streaming > mappings through SWIOTLB. > > A device marked with DEV_FLAG_DMA_CC_PRIVATE can reach private memory > directly. Add dma_require_decrypted() to combine force_dma_unencrypted() > with the new device flag, and use it throughout the generic DMA code. > > Signed-off-by: Nicolin Chen The change look good, but I'm not really happy to see the mix of unencrypted and decrypted terms. Wasn't there a consensus which one will be used? > --- > include/linux/dma-direct.h | 7 ++++++- > kernel/dma/direct.c | 16 ++++++++-------- > kernel/dma/mapping.c | 2 +- > kernel/dma/swiotlb.c | 2 +- > 4 files changed, 16 insertions(+), 11 deletions(-) > > diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h > index daa31a1adf7b0..fb35ca27941cc 100644 > --- a/include/linux/dma-direct.h > +++ b/include/linux/dma-direct.h > @@ -134,6 +134,11 @@ static inline bool force_dma_unencrypted(struct device *dev) > } > #endif /* CONFIG_ARCH_HAS_FORCE_DMA_UNENCRYPTED */ > > +static inline bool dma_require_decrypted(struct device *dev) > +{ > + return !dev_dma_cc_private(dev) && force_dma_unencrypted(dev); > +} > + > static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size, > bool is_ram, unsigned long attrs) > { > @@ -146,7 +151,7 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size, > * requires unencrypted DMA addresses. Treat it as not DMA-capable > * so the caller can fall back to a suitable SWIOTLB pool. > */ > - if (!(attrs & DMA_ATTR_CC_SHARED) && force_dma_unencrypted(dev)) > + if (!(attrs & DMA_ATTR_CC_SHARED) && dma_require_decrypted(dev)) > return false; > > if (is_ram && !IS_ENABLED(CONFIG_ARCH_DMA_ADDR_T_64BIT) && > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 25e9a86835fd3..b3b9ff090c590 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -41,7 +41,7 @@ static inline struct page *dma_direct_to_page(struct device *dev, > > u64 dma_direct_get_required_mask(struct device *dev) > { > - bool require_decrypted = force_dma_unencrypted(dev); > + bool require_decrypted = dma_require_decrypted(dev); > phys_addr_t phys = ((phys_addr_t)max_pfn << PAGE_SHIFT) - 1; > u64 max_dma = phys_to_dma_direct(dev, phys, require_decrypted); > > @@ -72,7 +72,7 @@ static gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 *phys_limit) > > bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) > { > - bool require_decrypted = force_dma_unencrypted(dev); > + bool require_decrypted = dma_require_decrypted(dev); > dma_addr_t dma_addr = phys_to_dma_direct(dev, phys, require_decrypted); > > if (dma_addr == DMA_MAPPING_ERROR) > @@ -226,7 +226,7 @@ void *dma_direct_alloc(struct device *dev, size_t size, > struct page *page; > void *cpu_addr; > > - if (force_dma_unencrypted(dev)) > + if (dma_require_decrypted(dev)) > attrs |= __DMA_ATTR_ALLOC_CC_SHARED; > > if (attrs & __DMA_ATTR_ALLOC_CC_SHARED) { > @@ -385,7 +385,7 @@ void dma_direct_free(struct device *dev, size_t size, > * If the allocation used decrypted/shared backing pages, restore > * the encryption state on free. > */ > - if (force_dma_unencrypted(dev)) > + if (dma_require_decrypted(dev)) > attrs |= __DMA_ATTR_ALLOC_CC_SHARED; > > if (attrs & __DMA_ATTR_ALLOC_CC_SHARED) > @@ -452,7 +452,7 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size, > struct page *page; > void *cpu_addr; > > - if (force_dma_unencrypted(dev)) > + if (dma_require_decrypted(dev)) > attrs |= __DMA_ATTR_ALLOC_CC_SHARED; > > if ((attrs & __DMA_ATTR_ALLOC_CC_SHARED) && dma_direct_use_pool(dev, gfp)) > @@ -496,7 +496,7 @@ void dma_direct_free_pages(struct device *dev, size_t size, > * if the device had requested for an unencrypted buffer, > * convert it to encrypted on free > */ > - bool mark_mem_encrypted = force_dma_unencrypted(dev); > + bool mark_mem_encrypted = dma_require_decrypted(dev); > > /* If page is not from an atomic pool, dma_free_from_pool_page() fails */ > if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) && > @@ -665,7 +665,7 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma, > const pgoff_t pgoff_end = vma_end_pgoff(vma); > int ret = -ENXIO; > > - if (force_dma_unencrypted(dev)) > + if (dma_require_decrypted(dev)) > attrs |= DMA_ATTR_CC_SHARED; > > vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs); > @@ -814,7 +814,7 @@ size_t dma_direct_max_mapping_size(struct device *dev) > /* If SWIOTLB is active, use its maximum mapping size */ > if (is_swiotlb_active(dev) && > (dma_addressing_limited(dev) || is_swiotlb_force_bounce(dev) || > - force_dma_unencrypted(dev))) > + dma_require_decrypted(dev))) > return swiotlb_max_mapping_size(dev); > > return SIZE_MAX; > diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c > index ded585b39fb92..0252473edd0b5 100644 > --- a/kernel/dma/mapping.c > +++ b/kernel/dma/mapping.c > @@ -673,7 +673,7 @@ void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, > return NULL; > } > > - if (force_dma_unencrypted(dev)) > + if (dma_require_decrypted(dev)) > attrs |= __DMA_ATTR_ALLOC_CC_SHARED; > > if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr)) { > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index 2c57b49ac7c06..ddfc4533934a2 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -1550,7 +1550,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr, > if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) { > > /* swiotlb pool is incorrect for this device */ > - if (unlikely(mem->cc_shared != force_dma_unencrypted(dev))) > + if (unlikely(mem->cc_shared != dma_require_decrypted(dev))) > return (phys_addr_t)DMA_MAPPING_ERROR; > > } else if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) { Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland