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Fri, 27 Aug 2021 09:53:53 +0100 From: John Garry Subject: Re: [PATCH v11 10/12] vduse: Implement an MMU-based software IOTLB To: Xie Yongji , , , , , , , , , , , , , , , , , , , , , References: <20210818120642.165-1-xieyongji@bytedance.com> <20210818120642.165-11-xieyongji@bytedance.com> Message-ID: <2d807de3-e245-c2fb-ae5d-7cacbe35dfcb@huawei.com> Date: Fri, 27 Aug 2021 09:57:42 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <20210818120642.165-11-xieyongji@bytedance.com> Content-Language: en-US X-Originating-IP: [10.47.92.37] X-ClientProxiedBy: lhreml706-chm.china.huawei.com (10.201.108.55) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Cc: kvm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, songmuchun@bytedance.com, linux-fsdevel@vger.kernel.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 18/08/2021 13:06, Xie Yongji wrote: > + > +static dma_addr_t > +vduse_domain_alloc_iova(struct iova_domain *iovad, > + unsigned long size, unsigned long limit) > +{ > + unsigned long shift = iova_shift(iovad); > + unsigned long iova_len = iova_align(iovad, size) >> shift; > + unsigned long iova_pfn; > + > + /* > + * Freeing non-power-of-two-sized allocations back into the IOVA caches > + * will come back to bite us badly, so we have to waste a bit of space > + * rounding up anything cacheable to make sure that can't happen. The > + * order of the unadjusted size will still match upon freeing. > + */ > + if (iova_len < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1))) > + iova_len = roundup_pow_of_two(iova_len); Whether it's proper to use this "fast" API or not here, this seems to be copied verbatim from dma-iommu.c, which tells me that something should be factored out. Indeed, this rounding up seems a requirement of the rcache, so not sure why this is not done there. > + iova_pfn = alloc_iova_fast(iovad, iova_len, limit >> shift, true); _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu