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([2404:f801:9000:1a:efea::4b1]) by smtp.gmail.com with ESMTPSA id j6sm23210086pji.23.2021.07.21.08.11.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 21 Jul 2021 08:11:41 -0700 (PDT) Subject: Re: [Resend RFC PATCH V4 09/13] x86/Swiotlb/HV: Add Swiotlb bounce buffer remap function for HV IVM To: Christoph Hellwig Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, joro@8bytes.org, will@kernel.org, davem@davemloft.net, kuba@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com, arnd@arndb.de, m.szyprowski@samsung.com, robin.murphy@arm.com, kirill.shutemov@linux.intel.com, akpm@linux-foundation.org, rppt@kernel.org, Tianyu.Lan@microsoft.com, thomas.lendacky@amd.com, ardb@kernel.org, robh@kernel.org, nramas@linux.microsoft.com, pgonda@google.com, martin.b.radev@gmail.com, david@redhat.com, krish.sadhukhan@oracle.com, saravanand@fb.com, xen-devel@lists.xenproject.org, keescook@chromium.org, rientjes@google.com, hannes@cmpxchg.org, michael.h.kelley@microsoft.com, iommu@lists.linux-foundation.org, linux-arch@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, netdev@vger.kernel.org, vkuznets@redhat.com, brijesh.singh@amd.com, anparri@microsoft.com References: <20210707154629.3977369-1-ltykernel@gmail.com> <20210707154629.3977369-10-ltykernel@gmail.com> <20210720135437.GA13554@lst.de> <8f1a285d-4b67-8041-d326-af565b2756c0@gmail.com> <20210721143355.GA10848@lst.de> From: Tianyu Lan Message-ID: <0e2ca0e2-201d-68d4-5dc0-7341f8e9106a@gmail.com> Date: Wed, 21 Jul 2021 23:11:26 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210721143355.GA10848@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On 7/21/2021 10:33 PM, Christoph Hellwig wrote: > On Wed, Jul 21, 2021 at 06:28:48PM +0800, Tianyu Lan wrote: >> dma_mmap_attrs() and dma_get_sgtable_attrs() get input virtual address >> belonging to backing memory with struct page and returns bounce buffer >> dma physical address which is below shared_gpa_boundary(vTOM) and passed >> to Hyper-V via vmbus protocol. >> >> The new map virtual address is only to access bounce buffer in swiotlb >> code and will not be used other places. It's stored in the mem->vstart. >> So the new API set_memory_decrypted_map() in this series is only called >> in the swiotlb code. Other platforms may replace set_memory_decrypted() >> with set_memory_decrypted_map() as requested. > > It seems like you are indeed not using these new helpers in > dma_direct_alloc. How is dma_alloc_attrs/dma_alloc_coherent going to > work on these systems? > Current vmbus device drivers don't use dma_alloc_attrs/dma_alloc _coherent() because vmbus driver allocates ring buffer for all devices. Ring buffer has been marked decrypted and remapped in vmbus driver. Netvsc and storvsc drivers just need to use dma_map_single/dma_map_page().