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Thu, 19 Sep 2019 08:10:04 -0700 (PDT) Date: Thu, 19 Sep 2019 17:10:02 +0200 From: Jean-Philippe Brucker To: Auger Eric Subject: Re: [PATCH 8/8] iommu/arm-smmu-v3: Add support for PCI PASID Message-ID: <20190919151002.GF1013538@lophozonia> References: <20190610184714.6786-1-jean-philippe.brucker@arm.com> <20190610184714.6786-9-jean-philippe.brucker@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190919_081006_826799_38CAA906 X-CRM114-Status: GOOD ( 17.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, jacob.jun.pan@linux.intel.com, Jean-Philippe Brucker , joro@8bytes.org, will.deacon@arm.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, robh+dt@kernel.org, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jul 08, 2019 at 09:58:16AM +0200, Auger Eric wrote: > > + ret = pci_enable_pasid(pdev, features); > > + if (!ret) > > + master->ssid_bits = min_t(u8, ilog2(num_pasids), > > + master->smmu->ssid_bits); > I don't really get why this setting is conditional to the success of > pci_enabled_pasid and not num_pasids > 0. num_pasids only contains the value of the PCIe PASID capability. If pci_enable_pasid() fails then we want to leave master->ssid_bits to 0 so that we report to users that SVA and AUXD aren't supported. > If it fails the ssid_bits is set to min(smmu->ssid_bits, > fwspec->num_pasid_bits) anyway. > > > + return ret; > > +} > > + > > +static void arm_smmu_disable_pasid(struct arm_smmu_master *master) > > +{ > > + struct pci_dev *pdev; > > + > > + if (!dev_is_pci(master->dev)) > > + return; > > + > > + pdev = to_pci_dev(master->dev); > > + > > + if (!pdev->pasid_enabled) > > + return; > > + > > + pci_disable_pasid(pdev); > > + master->ssid_bits = 0; > in case of a platform device you leave the ssid_bits to a value != 0. Is > that what you want? Yes, this is only for PCI devices, there is no standard way of disabling PASID in platform devices. We just take whatever the firmware gives us. > > +} > > + > > static void arm_smmu_detach_dev(struct arm_smmu_master *master) > > { > > unsigned long flags; > > @@ -2413,6 +2456,9 @@ static int arm_smmu_add_device(struct device *dev) > > > > master->ssid_bits = min(smmu->ssid_bits, fwspec->num_pasid_bits); > > > > + /* Note that PASID must be enabled before, and disabled after ATS */ > > + arm_smmu_enable_pasid(master); > In case the call fails, don't you want to handle the error and reset the > ssid_bits? This function fails if the device doesn't support PASID, and we leave ssid_bits to 0. That said, I think it would be nicer to move the above line (that deals with fwspec) into arm_smmu_enable_pasid() Thanks, Jean _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel