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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8b02aa4f1f9sm257474006d6.0.2026.04.27.06.49.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Apr 2026 06:49:04 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wHMKd-00000003T5r-43dX; Mon, 27 Apr 2026 10:49:03 -0300 Date: Mon, 27 Apr 2026 10:49:03 -0300 From: Jason Gunthorpe To: "Aneesh Kumar K.V (Arm)" Cc: linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-coco@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, Catalin Marinas , Marc Zyngier , Marek Szyprowski , Robin Murphy , Steven Price , Suzuki K Poulose , Thomas Gleixner , Will Deacon Subject: Re: [PATCH v4 2/3] swiotlb: dma: its: Enforce host page-size alignment for shared buffers Message-ID: <20260427134903.GA740385@ziepe.ca> References: <20260427063108.909019-1-aneesh.kumar@kernel.org> <20260427063108.909019-3-aneesh.kumar@kernel.org> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260427063108.909019-3-aneesh.kumar@kernel.org> On Mon, Apr 27, 2026 at 12:01:07PM +0530, Aneesh Kumar K.V (Arm) wrote: > When running private-memory guests, the guest kernel must apply additional > constraints when allocating buffers that are shared with the hypervisor. This patch has way too much stuff in it. I think your patch structure should be changed around 1) Patch to add mem_decrypt_granule_size(), and explain it as the alignment & size of what can be passed to set_memory_encrypted/decrypted() 2) Add support for mem_decrypt_granule_size() to ARM Then patches going caller by caller of set_memory_decrypted() to make them follow the new rule: 3) its 4) swiotlb 3) dma_alloc_coherent etc. don't forget about the new dma buf heaps too: drivers/dma-buf/heaps/system_heap.c: ret = set_memory_decrypted(addr, nr_pages); It is worth calling out in the cover letter that all the ARM CCA relevant places are fixed but drivers/hv/ is left for future. > @@ -33,18 +32,30 @@ int arm64_mem_crypt_ops_register(const struct arm64_mem_crypt_ops *ops) > > int set_memory_encrypted(unsigned long addr, int numpages) > { > - if (likely(!crypt_ops) || WARN_ON(!PAGE_ALIGNED(addr))) > + if (likely(!crypt_ops)) > return 0; > > + if (WARN_ON(!IS_ALIGNED(addr, mem_decrypt_granule_size()))) > + return -EINVAL; > + > + if (WARN_ON(!IS_ALIGNED(numpages << PAGE_SHIFT, mem_decrypt_granule_size()))) > + return -EINVAL; > + > return crypt_ops->encrypt(addr, numpages); > } > EXPORT_SYMBOL_GPL(set_memory_encrypted); > > int set_memory_decrypted(unsigned long addr, int numpages) > { > - if (likely(!crypt_ops) || WARN_ON(!PAGE_ALIGNED(addr))) > + if (likely(!crypt_ops)) > return 0; > > + if (WARN_ON(!IS_ALIGNED(addr, mem_decrypt_granule_size()))) > + return -EINVAL; > + > + if (WARN_ON(!IS_ALIGNED(numpages << PAGE_SHIFT, mem_decrypt_granule_size()))) > + return -EINVAL; > + > return crypt_ops->decrypt(addr, numpages); > } > EXPORT_SYMBOL_GPL(set_memory_decrypted); This should go in the ARM patch adding mem_decrypt_granule_size() to CCA > diff --git a/include/linux/mem_encrypt.h b/include/linux/mem_encrypt.h > index 07584c5e36fb..1e01c9ac697f 100644 > --- a/include/linux/mem_encrypt.h > +++ b/include/linux/mem_encrypt.h > @@ -11,6 +11,8 @@ > #define __MEM_ENCRYPT_H__ > > #ifndef __ASSEMBLY__ > +#include > +#include > > #ifdef CONFIG_ARCH_HAS_MEM_ENCRYPT > > @@ -54,6 +56,18 @@ > #define dma_addr_canonical(x) (x) > #endif > > +#ifndef mem_decrypt_granule_size > +static inline size_t mem_decrypt_granule_size(void) > +{ > + return PAGE_SIZE; > +} > +#endif > + > +static inline size_t mem_decrypt_align(size_t size) > +{ > + return ALIGN(size, mem_decrypt_granule_size()); > +} > + > #endif /* __ASSEMBLY__ */ > > #endif /* __MEM_ENCRYPT_H__ */ I know it seems a bit small, but put this in its own patch and explain how it works. I'd also like to see a kdoc here, and add a kdoc to set_memory_decrypted() that links back so people have a better chance to know about this. Jason