From: Jacob Pan <jacob.jun.pan@linux.intel.com> To: iommu@lists.linux-foundation.org, LKML <linux-kernel@vger.kernel.org>, "Lu Baolu" <baolu.lu@linux.intel.com>, Joerg Roedel <joro@8bytes.org>, David Woodhouse <dwmw2@infradead.org> Cc: Yi Liu <yi.l.liu@intel.com>, "Tian, Kevin" <kevin.tian@intel.com>, Raj Ashok <ashok.raj@intel.com>, Eric Auger <eric.auger@redhat.com>, Jacob Pan <jacob.jun.pan@linux.intel.com> Subject: [PATCH v4 7/7] iommu/vt-d: Disable multiple GPASID-dev bind Date: Mon, 6 Jul 2020 17:12:54 -0700 [thread overview] Message-ID: <1594080774-33413-8-git-send-email-jacob.jun.pan@linux.intel.com> (raw) In-Reply-To: <1594080774-33413-1-git-send-email-jacob.jun.pan@linux.intel.com> For the unlikely use case where multiple aux domains from the same pdev are attached to a single guest and then bound to a single process (thus same PASID) within that guest, we cannot easily support this case by refcounting the number of users. As there is only one SL page table per PASID while we have multiple aux domains thus multiple SL page tables for the same PASID. Extra unbinding guest PASID can happen due to race between normal and exception cases. Termination of one aux domain may affect others unless we actively track and switch aux domains to ensure the validity of SL page tables and TLB states in the shared PASID entry. Support for sharing second level PGDs across domains can reduce the complexity but this is not available due to the limitations on VFIO container architecture. We can revisit this decision once sharing PGDs are available. Overall, the complexity and potential glitch do not warrant this unlikely use case thereby removed by this patch. Fixes: 56722a4398a30 ("iommu/vt-d: Add bind guest PASID support") Acked-by: Lu Baolu <baolu.lu@linux.intel.com> Cc: Kevin Tian <kevin.tian@intel.com> Cc: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Liu Yi L <yi.l.liu@intel.com> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> --- drivers/iommu/intel/svm.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c index 6c87c807a0ab..d386853121a2 100644 --- a/drivers/iommu/intel/svm.c +++ b/drivers/iommu/intel/svm.c @@ -277,20 +277,16 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev, goto out; } + /* + * Do not allow multiple bindings of the same device-PASID since + * there is only one SL page tables per PASID. We may revisit + * once sharing PGD across domains are supported. + */ for_each_svm_dev(sdev, svm, dev) { - /* - * For devices with aux domains, we should allow - * multiple bind calls with the same PASID and pdev. - */ - if (iommu_dev_feature_enabled(dev, - IOMMU_DEV_FEAT_AUX)) { - sdev->users++; - } else { - dev_warn_ratelimited(dev, - "Already bound with PASID %u\n", - svm->pasid); - ret = -EBUSY; - } + dev_warn_ratelimited(dev, + "Already bound with PASID %u\n", + svm->pasid); + ret = -EBUSY; goto out; } } else { -- 2.7.4
WARNING: multiple messages have this Message-ID (diff)
From: Jacob Pan <jacob.jun.pan@linux.intel.com> To: iommu@lists.linux-foundation.org, LKML <linux-kernel@vger.kernel.org>, "Lu Baolu" <baolu.lu@linux.intel.com>, Joerg Roedel <joro@8bytes.org>, David Woodhouse <dwmw2@infradead.org> Cc: "Tian, Kevin" <kevin.tian@intel.com>, Raj Ashok <ashok.raj@intel.com> Subject: [PATCH v4 7/7] iommu/vt-d: Disable multiple GPASID-dev bind Date: Mon, 6 Jul 2020 17:12:54 -0700 [thread overview] Message-ID: <1594080774-33413-8-git-send-email-jacob.jun.pan@linux.intel.com> (raw) In-Reply-To: <1594080774-33413-1-git-send-email-jacob.jun.pan@linux.intel.com> For the unlikely use case where multiple aux domains from the same pdev are attached to a single guest and then bound to a single process (thus same PASID) within that guest, we cannot easily support this case by refcounting the number of users. As there is only one SL page table per PASID while we have multiple aux domains thus multiple SL page tables for the same PASID. Extra unbinding guest PASID can happen due to race between normal and exception cases. Termination of one aux domain may affect others unless we actively track and switch aux domains to ensure the validity of SL page tables and TLB states in the shared PASID entry. Support for sharing second level PGDs across domains can reduce the complexity but this is not available due to the limitations on VFIO container architecture. We can revisit this decision once sharing PGDs are available. Overall, the complexity and potential glitch do not warrant this unlikely use case thereby removed by this patch. Fixes: 56722a4398a30 ("iommu/vt-d: Add bind guest PASID support") Acked-by: Lu Baolu <baolu.lu@linux.intel.com> Cc: Kevin Tian <kevin.tian@intel.com> Cc: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Liu Yi L <yi.l.liu@intel.com> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> --- drivers/iommu/intel/svm.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c index 6c87c807a0ab..d386853121a2 100644 --- a/drivers/iommu/intel/svm.c +++ b/drivers/iommu/intel/svm.c @@ -277,20 +277,16 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev, goto out; } + /* + * Do not allow multiple bindings of the same device-PASID since + * there is only one SL page tables per PASID. We may revisit + * once sharing PGD across domains are supported. + */ for_each_svm_dev(sdev, svm, dev) { - /* - * For devices with aux domains, we should allow - * multiple bind calls with the same PASID and pdev. - */ - if (iommu_dev_feature_enabled(dev, - IOMMU_DEV_FEAT_AUX)) { - sdev->users++; - } else { - dev_warn_ratelimited(dev, - "Already bound with PASID %u\n", - svm->pasid); - ret = -EBUSY; - } + dev_warn_ratelimited(dev, + "Already bound with PASID %u\n", + svm->pasid); + ret = -EBUSY; goto out; } } else { -- 2.7.4 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2020-07-07 0:06 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-07 0:12 [PATCH v4 0/7] iommu/vt-d: Misc tweaks and fixes for vSVA Jacob Pan 2020-07-07 0:12 ` Jacob Pan 2020-07-07 0:12 ` [PATCH v4 1/7] iommu/vt-d: Enforce PASID devTLB field mask Jacob Pan 2020-07-07 0:12 ` Jacob Pan 2020-07-07 0:12 ` [PATCH v4 2/7] iommu/vt-d: Remove global page support in devTLB flush Jacob Pan 2020-07-07 0:12 ` Jacob Pan 2020-07-07 0:12 ` [PATCH v4 3/7] iommu/vt-d: Fix PASID devTLB invalidation Jacob Pan 2020-07-07 0:12 ` Jacob Pan 2020-07-16 7:52 ` Auger Eric 2020-07-16 7:52 ` Auger Eric 2020-07-07 0:12 ` [PATCH v4 4/7] iommu/vt-d: Handle non-page aligned address Jacob Pan 2020-07-07 0:12 ` Jacob Pan 2020-07-07 13:32 ` kernel test robot 2020-07-07 13:32 ` kernel test robot 2020-07-07 13:32 ` kernel test robot 2020-07-09 1:10 ` [kbuild-all] " Li, Philip 2020-07-09 1:10 ` Li, Philip 2020-07-09 1:10 ` [kbuild-all] " Li, Philip 2020-07-16 7:51 ` Auger Eric 2020-07-16 7:51 ` Auger Eric 2020-07-21 16:50 ` Jacob Pan 2020-07-21 16:50 ` Jacob Pan 2020-07-22 1:01 ` Lu Baolu 2020-07-22 1:01 ` Lu Baolu 2020-07-22 18:20 ` Jacob Pan 2020-07-22 18:20 ` Jacob Pan 2020-07-07 0:12 ` [PATCH v4 5/7] iommu/vt-d: Fix devTLB flush for vSVA Jacob Pan 2020-07-07 0:12 ` Jacob Pan 2020-07-07 0:12 ` [PATCH v4 6/7] iommu/vt-d: Warn on out-of-range invalidation address Jacob Pan 2020-07-07 0:12 ` Jacob Pan 2020-07-16 8:40 ` Auger Eric 2020-07-16 8:40 ` Auger Eric 2020-07-07 0:12 ` Jacob Pan [this message] 2020-07-07 0:12 ` [PATCH v4 7/7] iommu/vt-d: Disable multiple GPASID-dev bind Jacob Pan
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