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16 Mar 2021 02:23:35 -0700 Date: Tue, 16 Mar 2021 17:17:51 +0800 From: Yi Sun To: Keqian Zhu Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, Alex Williamson , Robin Murphy , Will Deacon , Kirti Wankhede , Cornelia Huck , Marc Zyngier , Catalin Marinas , Mark Rutland , James Morse , Suzuki K Poulose , wanghaibin.wang@huawei.com, jiangkunkun@huawei.com, yuzenghui@huawei.com, lushenming@huawei.com Subject: Re: [PATCH v2 04/11] iommu/arm-smmu-v3: Split block descriptor when start dirty log Message-ID: <20210316091751.GN28580@yi.y.sun> References: <20210310090614.26668-1-zhukeqian1@huawei.com> <20210310090614.26668-5-zhukeqian1@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210310090614.26668-5-zhukeqian1@huawei.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210316_092600_382188_A3AD9A59 X-CRM114-Status: GOOD ( 20.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 21-03-10 17:06:07, Keqian Zhu wrote: > From: jiangkunkun > > Block descriptor is not a proper granule for dirty log tracking. > Take an extreme example, if DMA writes one byte, under 1G mapping, > the dirty amount reported to userspace is 1G, but under 4K mapping, > the dirty amount is just 4K. > > This adds a new interface named start_dirty_log in iommu layer and > arm smmuv3 implements it, which splits block descriptor to an span > of page descriptors. Other types of IOMMU will perform architecture > specific actions to start dirty log. > > To allow code reuse, the split_block operation is realized as an > iommu_ops too. We flush all iotlbs after the whole procedure is > completed to ease the pressure of iommu, as we will hanle a huge > range of mapping in general. > > Spliting block does not simultaneously work with other pgtable ops, > as the only designed user is vfio, which always hold a lock, so race > condition is not considered in the pgtable ops. > > Co-developed-by: Keqian Zhu > Signed-off-by: Kunkun Jiang > --- > > changelog: > > v2: > - Change the return type of split_block(). size_t -> int. > - Change commit message to properly describe race condition. (Robin) > - Change commit message to properly describe the need of split block. > - Add a new interface named start_dirty_log(). (Sun Yi) > - Change commit message to explain the realtionship of split_block() and start_dirty_log(). > > --- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 52 +++++++++ > drivers/iommu/io-pgtable-arm.c | 122 ++++++++++++++++++++ > drivers/iommu/iommu.c | 48 ++++++++ > include/linux/io-pgtable.h | 2 + > include/linux/iommu.h | 24 ++++ > 5 files changed, 248 insertions(+) > Could you please split iommu common interface to a separate patch? This may make review and comments easier. IMHO, I think the start/stop interfaces could be merged into one, e.g: int iommu_domain_set_hwdbm(struct iommu_domain *domain, bool enable, unsigned long iova, size_t size, int prot); Same comments to patch 5. BRs, Yi Sun > -- > 2.19.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel