From: Lu Baolu <baolu.lu@linux.intel.com> To: "Tian, Kevin" <kevin.tian@intel.com>, Jason Gunthorpe <jgg@nvidia.com> Cc: "Raj, Ashok" <ashok.raj@intel.com>, Will Deacon <will@kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>, Christoph Hellwig <hch@infradead.org>, "Alex Williamson \(alex.williamson@redhat.com\)" <alex.williamson@redhat.com>, "Pan, Jacob jun" <jacob.jun.pan@intel.com>, Robin Murphy <robin.murphy@arm.com>, Jean-Philippe Brucker <jean-philippe@linaro.com> Subject: Re: [PATCH RFC v2 02/11] iommu: Add iommu_group_singleton_lockdown() Date: Wed, 6 Apr 2022 19:03:12 +0800 [thread overview] Message-ID: <a5542ef5-bacc-f527-0295-ffdedefcbdd9@linux.intel.com> (raw) In-Reply-To: <BN9PR11MB527646AB4F3FE8E9F97ECB8D8CE79@BN9PR11MB5276.namprd11.prod.outlook.com> On 2022/4/6 18:44, Tian, Kevin wrote: >> From: Lu Baolu <baolu.lu@linux.intel.com> >> Sent: Wednesday, April 6, 2022 6:02 PM >> >> Hi Kevin, >> >> On 2022/4/2 15:12, Tian, Kevin wrote: >>>>>> Add a flag to the group that positively indicates the group can never >>>>>> have more than one member, even after hot plug. eg because it is >>>>>> impossible due to ACS, or lack of bridges, and so on. >>>>> OK, I see your point. It essentially refers to a singleton group which >>>>> is immutable to hotplug. >>>> Yes, known at creation time, not retroactively enforced because >>>> someone used SVA >>>> >>> We may check following conditions to set the immutable flag when >>> a new group is created for a device in pci_device_group(): >>> >>> 1) ACS is enabled in the upstream path of the device; >>> 2) the device is single function or ACS is enabled on a multi-function device; >>> 3) the device type is PCI_EXP_TYPE_ENDPOINT (thus no hotplug); >>> 4) no 'dma aliasing' on this device; >>> >>> The last one is a bit conservative as it also precludes a device which aliasing >>> dma due to quirks from being treated as a singleton group. But doing so >>> saves the effort on trying to separate different aliasing scenarios as defined >>> in pci_for_each_dma_alias(). Probably we can go this way as the first step. >>> >>> Once the flag is set on a group no other event can change it. If a new >>> identified device hits an existing singleton group in pci_device_group() >>> then it's a bug. >> >> How about below implementation? >> >> /* callback for pci_for_each_dma_alias() */ >> static int has_pci_alias(struct pci_dev *pdev, u16 alias, void *opaque) >> { >> return -EEXIST; >> } >> >> static bool pci_dev_is_immutably_isolated(struct pci_dev *pdev) >> { >> /* Skip bridges. */ >> if (pci_is_bridge(pdev)) >> return false; >> >> /* Either connect to root bridge or the ACS-enabled bridge. */ >> if (!pci_is_root_bus(pdev->bus) && >> !pci_acs_enabled(pdev->bus->self, REQ_ACS_FLAGS)) >> return false; > > it's not sufficient to just check the non-root bridge itself. This needs to > cover the entire path from the bridge to the root port, as pci_device_group() > does. Yes! You are right. > >> >> /* ACS is required for MFD. */ >> if (pdev->multifunction && !pci_acs_enabled(pdev, REQ_ACS_FLAGS)) >> return false; > > Above two checks be replaced by a simple check as below: > > if (!pci_acs_path_enabled(pdev, NULL, REQ_ACS_FLAGS)) > return false; If !pdev->multifunction, do we still need to start from the device itself? ACS is only for MFDs and bridges, do I understand it right? Do we need to consider the SRIOV case? > >> >> /* Make sure no PCI alias. */ >> if (pci_for_each_dma_alias(pdev, has_pci_alias, NULL)) >> return false; >> >> return true; >> } >> >> I didn't get why do we need to check the PCI_EXP_TYPE_ENDPOINT device >> type. Can you please elaborate a bit more? >> > > I didn't know there is a pci_is_bridge() facility thus be conservative > to restrict it to only endpoint device. If checking pci_is_bridge() alone > excludes any hotplug possibility, then it's definitely better. Okay! Thanks! > Thanks > Kevin Best regards, baolu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
WARNING: multiple messages have this Message-ID (diff)
From: Lu Baolu <baolu.lu@linux.intel.com> To: "Tian, Kevin" <kevin.tian@intel.com>, Jason Gunthorpe <jgg@nvidia.com> Cc: baolu.lu@linux.intel.com, "Alex Williamson (alex.williamson@redhat.com)" <alex.williamson@redhat.com>, "Raj, Ashok" <ashok.raj@intel.com>, Jean-Philippe Brucker <jean-philippe@linaro.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Christoph Hellwig <hch@infradead.org>, "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>, "Pan, Jacob jun" <jacob.jun.pan@intel.com>, Will Deacon <will@kernel.org>, Robin Murphy <robin.murphy@arm.com> Subject: Re: [PATCH RFC v2 02/11] iommu: Add iommu_group_singleton_lockdown() Date: Wed, 6 Apr 2022 19:03:12 +0800 [thread overview] Message-ID: <a5542ef5-bacc-f527-0295-ffdedefcbdd9@linux.intel.com> (raw) In-Reply-To: <BN9PR11MB527646AB4F3FE8E9F97ECB8D8CE79@BN9PR11MB5276.namprd11.prod.outlook.com> On 2022/4/6 18:44, Tian, Kevin wrote: >> From: Lu Baolu <baolu.lu@linux.intel.com> >> Sent: Wednesday, April 6, 2022 6:02 PM >> >> Hi Kevin, >> >> On 2022/4/2 15:12, Tian, Kevin wrote: >>>>>> Add a flag to the group that positively indicates the group can never >>>>>> have more than one member, even after hot plug. eg because it is >>>>>> impossible due to ACS, or lack of bridges, and so on. >>>>> OK, I see your point. It essentially refers to a singleton group which >>>>> is immutable to hotplug. >>>> Yes, known at creation time, not retroactively enforced because >>>> someone used SVA >>>> >>> We may check following conditions to set the immutable flag when >>> a new group is created for a device in pci_device_group(): >>> >>> 1) ACS is enabled in the upstream path of the device; >>> 2) the device is single function or ACS is enabled on a multi-function device; >>> 3) the device type is PCI_EXP_TYPE_ENDPOINT (thus no hotplug); >>> 4) no 'dma aliasing' on this device; >>> >>> The last one is a bit conservative as it also precludes a device which aliasing >>> dma due to quirks from being treated as a singleton group. But doing so >>> saves the effort on trying to separate different aliasing scenarios as defined >>> in pci_for_each_dma_alias(). Probably we can go this way as the first step. >>> >>> Once the flag is set on a group no other event can change it. If a new >>> identified device hits an existing singleton group in pci_device_group() >>> then it's a bug. >> >> How about below implementation? >> >> /* callback for pci_for_each_dma_alias() */ >> static int has_pci_alias(struct pci_dev *pdev, u16 alias, void *opaque) >> { >> return -EEXIST; >> } >> >> static bool pci_dev_is_immutably_isolated(struct pci_dev *pdev) >> { >> /* Skip bridges. */ >> if (pci_is_bridge(pdev)) >> return false; >> >> /* Either connect to root bridge or the ACS-enabled bridge. */ >> if (!pci_is_root_bus(pdev->bus) && >> !pci_acs_enabled(pdev->bus->self, REQ_ACS_FLAGS)) >> return false; > > it's not sufficient to just check the non-root bridge itself. This needs to > cover the entire path from the bridge to the root port, as pci_device_group() > does. Yes! You are right. > >> >> /* ACS is required for MFD. */ >> if (pdev->multifunction && !pci_acs_enabled(pdev, REQ_ACS_FLAGS)) >> return false; > > Above two checks be replaced by a simple check as below: > > if (!pci_acs_path_enabled(pdev, NULL, REQ_ACS_FLAGS)) > return false; If !pdev->multifunction, do we still need to start from the device itself? ACS is only for MFDs and bridges, do I understand it right? Do we need to consider the SRIOV case? > >> >> /* Make sure no PCI alias. */ >> if (pci_for_each_dma_alias(pdev, has_pci_alias, NULL)) >> return false; >> >> return true; >> } >> >> I didn't get why do we need to check the PCI_EXP_TYPE_ENDPOINT device >> type. Can you please elaborate a bit more? >> > > I didn't know there is a pci_is_bridge() facility thus be conservative > to restrict it to only endpoint device. If checking pci_is_bridge() alone > excludes any hotplug possibility, then it's definitely better. Okay! Thanks! > Thanks > Kevin Best regards, baolu
next prev parent reply other threads:[~2022-04-06 11:03 UTC|newest] Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-29 5:37 [PATCH RFC v2 00/11] iommu: SVA and IOPF refactoring Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-29 5:37 ` [PATCH RFC v2 01/11] iommu: Add pasid_bits field in struct dev_iommu Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-29 21:00 ` Jacob Pan 2022-03-29 21:00 ` Jacob Pan 2022-03-30 4:30 ` Lu Baolu 2022-03-30 4:30 ` Lu Baolu 2022-03-30 7:05 ` Tian, Kevin 2022-03-30 7:05 ` Tian, Kevin 2022-03-30 11:58 ` Lu Baolu 2022-03-30 11:58 ` Lu Baolu 2022-03-29 5:37 ` [PATCH RFC v2 02/11] iommu: Add iommu_group_singleton_lockdown() Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-29 8:42 ` Tian, Kevin 2022-03-29 8:42 ` Tian, Kevin 2022-03-29 11:42 ` Jason Gunthorpe 2022-03-29 11:42 ` Jason Gunthorpe via iommu 2022-03-30 6:50 ` Tian, Kevin 2022-03-30 6:50 ` Tian, Kevin 2022-03-30 11:57 ` Lu Baolu 2022-03-30 11:57 ` Lu Baolu 2022-03-30 11:58 ` Jason Gunthorpe via iommu 2022-03-30 11:58 ` Jason Gunthorpe 2022-03-30 14:12 ` Tian, Kevin 2022-03-30 14:12 ` Tian, Kevin 2022-03-30 14:30 ` Jason Gunthorpe 2022-03-30 14:30 ` Jason Gunthorpe via iommu 2022-04-02 7:12 ` Tian, Kevin 2022-04-02 7:12 ` Tian, Kevin 2022-04-02 23:29 ` Jason Gunthorpe 2022-04-02 23:29 ` Jason Gunthorpe via iommu 2022-04-06 10:02 ` Lu Baolu 2022-04-06 10:02 ` Lu Baolu 2022-04-06 10:44 ` Tian, Kevin 2022-04-06 10:44 ` Tian, Kevin 2022-04-06 11:03 ` Lu Baolu [this message] 2022-04-06 11:03 ` Lu Baolu 2022-04-06 23:56 ` Tian, Kevin 2022-04-06 23:56 ` Tian, Kevin 2022-03-30 14:18 ` Tian, Kevin 2022-03-30 14:18 ` Tian, Kevin 2022-03-30 15:04 ` Alex Williamson 2022-03-30 15:04 ` Alex Williamson 2022-04-04 5:43 ` Lu Baolu 2022-04-04 5:43 ` Lu Baolu 2022-04-04 17:24 ` Jason Gunthorpe via iommu 2022-04-04 17:24 ` Jason Gunthorpe 2022-04-05 6:12 ` Lu Baolu 2022-04-05 6:12 ` Lu Baolu 2022-04-05 14:10 ` Jason Gunthorpe via iommu 2022-04-05 14:10 ` Jason Gunthorpe 2022-04-06 9:51 ` Lu Baolu 2022-04-06 9:51 ` Lu Baolu 2022-04-01 6:20 ` Yi Liu 2022-04-01 6:20 ` Yi Liu 2022-04-01 11:52 ` Jason Gunthorpe 2022-04-01 11:52 ` Jason Gunthorpe via iommu 2022-03-30 4:59 ` Lu Baolu 2022-03-30 4:59 ` Lu Baolu 2022-03-30 6:55 ` Tian, Kevin 2022-03-30 6:55 ` Tian, Kevin 2022-04-01 5:49 ` Yi Liu 2022-04-01 5:49 ` Yi Liu 2022-03-29 5:37 ` [PATCH RFC v2 03/11] iommu/sva: Add iommu_domain type for SVA Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-29 21:38 ` Jacob Pan 2022-03-29 21:38 ` Jacob Pan 2022-03-30 4:35 ` Lu Baolu 2022-03-30 4:35 ` Lu Baolu 2022-03-30 19:02 ` Jason Gunthorpe 2022-03-30 19:02 ` Jason Gunthorpe via iommu 2022-04-02 8:43 ` Tian, Kevin 2022-04-02 8:43 ` Tian, Kevin 2022-04-02 23:32 ` Jason Gunthorpe 2022-04-02 23:32 ` Jason Gunthorpe via iommu 2022-04-04 6:09 ` Lu Baolu 2022-04-04 6:09 ` Lu Baolu 2022-04-06 1:00 ` Tian, Kevin 2022-04-06 1:00 ` Tian, Kevin 2022-04-06 1:23 ` Jason Gunthorpe via iommu 2022-04-06 1:23 ` Jason Gunthorpe 2022-04-06 5:58 ` Tian, Kevin 2022-04-06 5:58 ` Tian, Kevin 2022-04-06 12:32 ` Robin Murphy 2022-04-06 12:32 ` Robin Murphy 2022-04-06 13:06 ` Jason Gunthorpe via iommu 2022-04-06 13:06 ` Jason Gunthorpe 2022-04-06 13:37 ` Robin Murphy 2022-04-06 13:37 ` Robin Murphy 2022-04-06 14:01 ` Jason Gunthorpe via iommu 2022-04-06 14:01 ` Jason Gunthorpe 2022-04-07 0:11 ` Tian, Kevin 2022-04-07 0:11 ` Tian, Kevin 2022-03-29 5:37 ` [PATCH RFC v2 04/11] iommu: Add attach/detach_dev_pasid domain ops Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-30 19:08 ` Jason Gunthorpe 2022-03-30 19:08 ` Jason Gunthorpe via iommu 2022-04-04 6:47 ` Lu Baolu 2022-04-04 6:47 ` Lu Baolu 2022-03-29 5:37 ` [PATCH RFC v2 05/11] iommu/vt-d: Remove SVM_FLAG_SUPERVISOR_MODE suport Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-29 5:37 ` [PATCH RFC v2 06/11] iommu/vt-d: Add SVA domain support Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-30 19:09 ` Jason Gunthorpe 2022-03-30 19:09 ` Jason Gunthorpe via iommu 2022-04-04 6:52 ` Lu Baolu 2022-04-04 6:52 ` Lu Baolu 2022-03-29 5:37 ` [PATCH RFC v2 07/11] arm-smmu-v3/sva: " Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-29 5:37 ` [PATCH RFC v2 08/11] iommu/sva: Use attach/detach_pasid_dev in SVA interfaces Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-31 20:59 ` Jacob Pan 2022-03-31 20:59 ` Jacob Pan 2022-03-31 22:26 ` Jason Gunthorpe 2022-03-31 22:26 ` Jason Gunthorpe via iommu 2022-04-04 5:55 ` Lu Baolu 2022-04-04 5:55 ` Lu Baolu 2022-03-29 5:37 ` [PATCH RFC v2 09/11] iommu: Remove SVA related callbacks from iommu ops Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-29 5:37 ` [PATCH RFC v2 10/11] iommu: Per-domain I/O page fault handling Lu Baolu 2022-03-29 5:37 ` Lu Baolu 2022-03-29 5:38 ` [PATCH RFC v2 11/11] iommu: Rename iommu-sva-lib.{c,h} Lu Baolu 2022-03-29 5:38 ` Lu Baolu
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