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[34.143.210.2]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b15faded711sm9272213a12.66.2025.04.29.11.03.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Apr 2025 11:03:24 -0700 (PDT) Date: Tue, 29 Apr 2025 18:03:13 +0000 From: Pranjal Shrivastava To: Nicolin Chen Cc: jgg@nvidia.com, kevin.tian@intel.com, corbet@lwn.net, will@kernel.org, bagasdotme@gmail.com, robin.murphy@arm.com, joro@8bytes.org, thierry.reding@gmail.com, vdumpa@nvidia.com, jonathanh@nvidia.com, shuah@kernel.org, jsnitsel@redhat.com, nathan@kernel.org, peterz@infradead.org, yi.l.liu@intel.com, mshavit@google.com, zhangzekun11@huawei.com, iommu@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-tegra@vger.kernel.org, linux-kselftest@vger.kernel.org, patches@lists.linux.dev, mochs@nvidia.com, alok.a.tiwari@oracle.com, vasant.hegde@amd.com Subject: Re: [PATCH v2 08/22] iommufd: Abstract iopt_pin_pages and iopt_unpin_pages helpers Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250429_110325_887195_6330B1E3 X-CRM114-Status: GOOD ( 20.56 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Apr 28, 2025 at 04:34:14PM -0700, Nicolin Chen wrote: > On Mon, Apr 28, 2025 at 03:12:33PM -0700, Nicolin Chen wrote: > > On Mon, Apr 28, 2025 at 08:14:19PM +0000, Pranjal Shrivastava wrote: > > > On Fri, Apr 25, 2025 at 10:58:03PM -0700, Nicolin Chen wrote: > > > > + iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) { > > > > + unsigned long last = min(last_iova, iopt_area_last_iova(area)); > > > > + unsigned long last_index = iopt_area_iova_to_index(area, last); > > > > + unsigned long index = > > > > + iopt_area_iova_to_index(area, iter.cur_iova); > > > > + > > > > + if (area->prevent_access || > > > > > > Nit: > > > Shouldn't we return -EBUSY or something if (area->prevent_access == 1) ? > > > IIUC, this just means that an unmap attempt is in progress, hence avoid > > > accessing the area. > > > > Maybe. But this is what it was. So we need a different patch to > > change that. > > Rereading the code. The prevent_access is set by an unmap(), which > means there shouldn't be any pin() and rw() as the caller should > finish unmap() first. > > In the newer use case of vCMDQ, it's similar. If VMM is unmapping > the stage-2 mapping, it shouldn't try to allocate a vCMDQ. > > -EBUSY makes some sense, but -EINVAL could still stand. > > So, I am leaving it as is, since this patch is just about moving > the functions for sharing. Ack. I don't have a strong preference too. This should be fine, we can re-visit this if needed in the future. Reviewed-by: Pranjal Shrivastava > > Nicolin Thanks!