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b=P67NkgKpagD5QPwkoLn48IDjtjZ7XiI7hB74ktXAOzTjzFx25SdPGIQTsJPn3c/+1 7mKXhe/08HVsqBRSEOx0tOKdadCpjOBrUyOGIzap4a8CF3tcQQzVYOpA4KCKlbL9eG FZDNA127wqunzK1pyu+ixL9pn3cpHGQTiZ/HklwS4zlyqRfWpfZR7WpwvZo4s6XE1b 33uAWW/5I0UcpudrKi/56u1/L85PdWYLjkcUUGZXni1xcq/PN0bKJ29dpyNBUK3NkQ hg7XGXtOx8q1P8cuRCDFQtSWlcXwLibDCDFZaRJ8t0FlQaoTBba1d1kPOW8eXaQxfI AghFYrjiJkifw== Date: Mon, 18 Nov 2024 20:55:33 +0200 From: Leon Romanovsky To: Will Deacon Cc: Jens Axboe , Jason Gunthorpe , Robin Murphy , Joerg Roedel , Christoph Hellwig , Sagi Grimberg , Keith Busch , Bjorn Helgaas , Logan Gunthorpe , Yishai Hadas , Shameer Kolothum , Kevin Tian , Alex Williamson , Marek Szyprowski , =?iso-8859-1?B?Suly9G1l?= Glisse , Andrew Morton , Jonathan Corbet , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-rdma@vger.kernel.org, iommu@lists.linux.dev, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, Randy Dunlap Subject: Re: [PATCH v3 07/17] dma-mapping: Implement link/unlink ranges API Message-ID: <20241118185533.GA24154@unreal> References: <20241118145929.GB27795@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241118145929.GB27795@willie-the-truck> X-Rspamd-Queue-Id: 0E61B16001B X-Stat-Signature: r6jjoq67tpuhf6f48wke64am59r5f8me X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1731956106-578901 X-HE-Meta: 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 wEqK7nzT zozGiDU7V/zW5ZKIMjcbg8Hhwv/y5D9Csobxw3HFC3/N/4bAqryE7/oLVwzIkvMLnCE358Tp8OEJEDtJXT0yTwM5eptPiBz/RF4jFLXe1blIGDYh0+bw+ZW0+/fj7cQ9RO/5eACbzSFDA83/mIp5RnXZDiI2RvJggTM0VVnOW/PPp5ZhAxUnNIoIPb14WzvRaWjKs1ivQ03G5yj6zJ9fox+BhvcJeqsghLLL9ebkZrJxmbZZILqOdKU8OJd2I2GUTrgxdLUzY/Sq/oxfvZ8kDezI1sEYbhN2mOKlqxJm99kArILE= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Nov 18, 2024 at 02:59:30PM +0000, Will Deacon wrote: > On Sun, Nov 10, 2024 at 03:46:54PM +0200, Leon Romanovsky wrote: > > From: Leon Romanovsky > > > > Introduce new DMA APIs to perform DMA linkage of buffers > > in layers higher than DMA. > > > > In proposed API, the callers will perform the following steps. > > In map path: > > if (dma_can_use_iova(...)) > > dma_iova_alloc() > > for (page in range) > > dma_iova_link_next(...) > > dma_iova_sync(...) > > else > > /* Fallback to legacy map pages */ > > for (all pages) > > dma_map_page(...) > > > > In unmap path: > > if (dma_can_use_iova(...)) > > dma_iova_destroy() > > else > > for (all pages) > > dma_unmap_page(...) > > > > Signed-off-by: Leon Romanovsky > > --- > > drivers/iommu/dma-iommu.c | 259 ++++++++++++++++++++++++++++++++++++ > > include/linux/dma-mapping.h | 32 +++++ > > 2 files changed, 291 insertions(+) > <...> > > +static void __iommu_dma_iova_unlink(struct device *dev, > > + struct dma_iova_state *state, size_t offset, size_t size, > > + enum dma_data_direction dir, unsigned long attrs, > > + bool free_iova) > > +{ > > + struct iommu_domain *domain = iommu_get_dma_domain(dev); > > + struct iommu_dma_cookie *cookie = domain->iova_cookie; > > + struct iova_domain *iovad = &cookie->iovad; > > + dma_addr_t addr = state->addr + offset; > > + size_t iova_start_pad = iova_offset(iovad, addr); > > + struct iommu_iotlb_gather iotlb_gather; > > + size_t unmapped; > > + > > + if ((state->__size & DMA_IOVA_USE_SWIOTLB) || > > + (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))) > > + iommu_dma_iova_unlink_range_slow(dev, addr, size, dir, attrs); > > + > > + iommu_iotlb_gather_init(&iotlb_gather); > > + iotlb_gather.queued = free_iova && READ_ONCE(cookie->fq_domain); > > + > > + size = iova_align(iovad, size + iova_start_pad); > > + addr -= iova_start_pad; > > + unmapped = iommu_unmap_fast(domain, addr, size, &iotlb_gather); > > + WARN_ON(unmapped != size); > > Does the new API require that the 'size' passed to dma_iova_unlink() > exactly match the 'size' passed to the corresponding call to > dma_iova_link()? I ask because the IOMMU page-table code is built around > the assumption that partial unmap() operations never occur (i.e. > operations which could require splitting a huge mapping). We just > removed [1] that code from the Arm IO page-table implementations, so it > would be good to avoid adding it back for this. dma_iova_link/dma_iova_unlink() don't have any assumptions in addition to already existing for dma_map_sg/dma_unmap_sg(). In reality, it means that all calls to unlink will have same size as for link. Thanks > > Will > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux.git/commit/?h=arm/smmu&id=33729a5fc0caf7a97d20507acbeee6b012e7e519