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[35.189.192.250]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47f85c6ef25sm54228115f8f.36.2026.07.28.07.31.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jul 2026 07:31:36 -0700 (PDT) Date: Tue, 28 Jul 2026 14:31:30 +0000 From: Mostafa Saleh To: "Aneesh Kumar K.V (Arm)" Cc: iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, Robin Murphy , Marek Szyprowski , Will Deacon , Marc Zyngier , Steven Price , Suzuki K Poulose , Catalin Marinas , Jiri Pirko , Jason Gunthorpe , 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, Jason Gunthorpe , Jiri Pirko , Michael Kelley Subject: Re: [PATCH v8 19/23] dma-direct: select DMA address encoding from __DMA_ATTR_ALLOC_CC_SHARED Message-ID: References: <20260717180442.110954-1-aneesh.kumar@kernel.org> <20260717180442.110954-20-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-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260717180442.110954-20-aneesh.kumar@kernel.org> On Fri, Jul 17, 2026 at 11:34:37PM +0530, Aneesh Kumar K.V (Arm) wrote: > Make the dma-direct helpers derive the DMA address encoding from > __DMA_ATTR_ALLOC_CC_SHARED instead of implicitly relying on > force_dma_unencrypted() inside phys_to_dma_direct() > > Pass an explicit unencrypted/decrypted state into phys_to_dma_direct(), > make the alloc paths return DMA addresses that match the requested buffer > encryption state. Also only call dma_set_decrypted() when > __DMA_ATTR_ALLOC_CC_SHARED is actually set. > > Reviewed-by: Jason Gunthorpe > Tested-by: Jiri Pirko > Tested-by: Michael Kelley > Tested-by: Mostafa Saleh > Signed-off-by: Aneesh Kumar K.V (Arm) Reviewed-by: Mostafa Saleh Thanks, Mostafa > --- > kernel/dma/direct.c | 43 ++++++++++++++++++++++++++----------------- > 1 file changed, 26 insertions(+), 17 deletions(-) > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index f7f064323bd9..eb0ce0787885 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -26,11 +26,11 @@ > u64 zone_dma_limit __ro_after_init = DMA_BIT_MASK(24); > > static inline dma_addr_t phys_to_dma_direct(struct device *dev, > - phys_addr_t phys) > + phys_addr_t phys, bool unencrypted) > { > - if (force_dma_unencrypted(dev)) > + if (unencrypted) > return phys_to_dma_unencrypted(dev, phys); > - return phys_to_dma(dev, phys); > + return phys_to_dma_encrypted(dev, phys); > } > > static inline struct page *dma_direct_to_page(struct device *dev, > @@ -41,8 +41,9 @@ 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); > phys_addr_t phys = ((phys_addr_t)max_pfn << PAGE_SHIFT) - 1; > - u64 max_dma = phys_to_dma_direct(dev, phys); > + u64 max_dma = phys_to_dma_direct(dev, phys, require_decrypted); > > return (1ULL << (fls64(max_dma) - 1)) * 2 - 1; > } > @@ -71,7 +72,8 @@ 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) > { > - dma_addr_t dma_addr = phys_to_dma_direct(dev, phys); > + bool require_decrypted = force_dma_unencrypted(dev); > + dma_addr_t dma_addr = phys_to_dma_direct(dev, phys, require_decrypted); > > if (dma_addr == DMA_MAPPING_ERROR) > return false; > @@ -81,17 +83,18 @@ bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) > > static int dma_set_decrypted(struct device *dev, void *vaddr, size_t size) > { > - if (!force_dma_unencrypted(dev)) > - return 0; > - return set_memory_decrypted((unsigned long)vaddr, PFN_UP(size)); > + int ret; > + > + ret = set_memory_decrypted((unsigned long)vaddr, PFN_UP(size)); > + if (ret) > + pr_warn_ratelimited("leaking DMA memory that can't be decrypted\n"); > + return ret; > } > > static int dma_set_encrypted(struct device *dev, void *vaddr, size_t size) > { > int ret; > > - if (!force_dma_unencrypted(dev)) > - return 0; > ret = set_memory_encrypted((unsigned long)vaddr, PFN_UP(size)); > if (ret) > pr_warn_ratelimited("leaking DMA memory that can't be re-encrypted\n"); > @@ -171,7 +174,8 @@ static struct page *dma_direct_alloc_from_pool(struct device *dev, size_t size, > dma_coherent_ok); > if (!page) > return NULL; > - *dma_handle = phys_to_dma_direct(dev, page_to_phys(page)); > + *dma_handle = phys_to_dma_direct(dev, page_to_phys(page), > + attrs & __DMA_ATTR_ALLOC_CC_SHARED); > return page; > } > > @@ -187,9 +191,11 @@ static void *dma_direct_alloc_no_mapping(struct device *dev, size_t size, > /* remove any dirty cache lines on the kernel alias */ > if (!PageHighMem(page)) > arch_dma_prep_coherent(page, size); > - > - /* return the page pointer as the opaque cookie */ > - *dma_handle = phys_to_dma_direct(dev, page_to_phys(page)); > + /* > + * return the page pointer as the opaque cookie. > + * Never used for unencrypted allocation > + */ > + *dma_handle = phys_to_dma_encrypted(dev, page_to_phys(page)); > return page; > } > > @@ -329,7 +335,8 @@ void *dma_direct_alloc(struct device *dev, size_t size, > ret = uncached_cpu_addr; > } > > - *dma_handle = phys_to_dma_direct(dev, page_to_phys(page)); > + *dma_handle = phys_to_dma_direct(dev, page_to_phys(page), > + attrs & __DMA_ATTR_ALLOC_CC_SHARED); > return ret; > > > @@ -450,11 +457,13 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size, > return NULL; > > ret = page_address(page); > - if (dma_set_decrypted(dev, ret, size)) > + if ((attrs & __DMA_ATTR_ALLOC_CC_SHARED) && > + 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)); > + *dma_handle = phys_to_dma_direct(dev, page_to_phys(page), > + attrs & __DMA_ATTR_ALLOC_CC_SHARED); > return page; > out_leak_pages: > return NULL; > -- > 2.43.0 >