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b=ht2Sg2t2ndCjMGA6QKO2lqpTrzx5fDYVZJW7Ovgfr1eplx4adbkUHrvVY0Fu92JLt mU5W84MEOLzWeruLzCzFJBMcezP+9RWb4w2qbxVzYCrWWzfG7s4lg/Gv7+t1mLvgfO 2fdSWrA5Q1UyDcQM7GTChwnkpqlcbSPsNUt/V748Qr4OW0E18YwIXE9gUZ8xqbm3Pa QZ5HR5+kS74PefChnaUbAqlutm/0zUWk4Ir6koict+0o/SIMktXHfmKvALkPRAwy7e 60A1hFUaIMAvaXkUU5Xx3C78C3VfTgwAozfACG4DXiep2AGvT26MouaYytY3hJ3pYn tSYLgRXYv+5hA== Date: Fri, 5 Jul 2024 21:48:46 +0300 From: Leon Romanovsky To: Christoph Hellwig Cc: Robin Murphy , Jens Axboe , Jason Gunthorpe , Joerg Roedel , Will Deacon , Keith Busch , "Zeng, Oak" , Chaitanya Kulkarni , Sagi Grimberg , Bjorn Helgaas , Logan Gunthorpe , Yishai Hadas , Shameer Kolothum , Kevin Tian , Alex Williamson , Marek Szyprowski , =?iso-8859-1?B?Suly9G1l?= Glisse , Andrew Morton , linux-block@vger.kernel.org, linux-kernel@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 Subject: Re: [RFC PATCH v1 18/18] nvme-pci: use new dma API Message-ID: <20240705184846.GF95824@unreal> References: <47eb0510b0a6aa52d9f5665d75fa7093dd6af53f.1719909395.git.leon@kernel.org> <249ec228-4ffd-4121-bd51-f4a19275fee1@arm.com> <20240704171602.GE95824@unreal> <20240705055806.GA11885@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240705055806.GA11885@lst.de> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: DBBC680015 X-Stat-Signature: kxtm8oryr1m1jkiybk5qap3df47do834 X-HE-Tag: 1720205335-680053 X-HE-Meta: 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 qsW3nKMl 9dtPQ+D4wVR/jblO8HSWbIW9vF7ABotnLhwovr1c4b7aiwi6KxT4E+fw3BByQ2H0UEAxovhz9G6WEWhbK6HsFkgQARgQhTBJcIeXzK5Iu5eYcFgoZT91yViU7T5Y7oPN/RKTAHMcXgxAGb1uoysIV0DR0fwuDoLDNhms9593Ak6aA1T6eVnYaeqGjJ7LklZ8ItHHsrYFFI6W/8Mg4/i18e0Urcng5RKrEJVYq 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 Fri, Jul 05, 2024 at 07:58:06AM +0200, Christoph Hellwig wrote: > > This is exactly how dma_map_sg() works. > > Which dma_map_sg? swiotlb handling is implemented in the underlying > ops, dma-direct and dma-iommu specifically. > > dma-direct just iterates over the entries and calls dma_direct_map_page, > which does a per-entry decision to bounce based on > is_swiotlb_force_bounce, dma_capable and dma_kmalloc_needs_bounce. dma-direct is not going to have "use_iova" flag. Robin pointed to dma-iommu path. In that case the flow is dma_map_sg()->iommu_dma_map_sg()->dev_use_sg_swiotlb(). Thanks > >