From: Lu Baolu <baolu.lu@linux.intel.com> To: iommu@lists.linux-foundation.org, iommu@lists.linux.dev Cc: Kevin Tian <kevin.tian@intel.com>, Ashok Raj <ashok.raj@intel.com>, Liu Yi L <yi.l.liu@intel.com>, Jacob jun Pan <jacob.jun.pan@intel.com>, linux-kernel@vger.kernel.org, Lu Baolu <baolu.lu@linux.intel.com> Subject: [PATCH v4 01/11] iommu/vt-d: debugfs: Remove device_domain_lock usage Date: Wed, 6 Jul 2022 10:55:14 +0800 [thread overview] Message-ID: <20220706025524.2904370-2-baolu.lu@linux.intel.com> (raw) In-Reply-To: <20220706025524.2904370-1-baolu.lu@linux.intel.com> The domain_translation_struct debugfs node is used to dump the DMAR page tables for the PCI devices. It potentially races with setting domains to devices. The existing code uses the global spinlock device_domain_lock to avoid the races. This removes the use of device_domain_lock outside of iommu.c by replacing it with the group mutex lock. Using the group mutex lock is cleaner and more compatible to following cleanups. Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> --- drivers/iommu/intel/iommu.h | 1 - drivers/iommu/intel/debugfs.c | 43 +++++++++++++++++++++++++---------- drivers/iommu/intel/iommu.c | 2 +- 3 files changed, 32 insertions(+), 14 deletions(-) diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h index 8285fcfa5fea..8deb745d8b36 100644 --- a/drivers/iommu/intel/iommu.h +++ b/drivers/iommu/intel/iommu.h @@ -480,7 +480,6 @@ enum { #define VTD_FLAG_SVM_CAPABLE (1 << 2) extern int intel_iommu_sm; -extern spinlock_t device_domain_lock; #define sm_supported(iommu) (intel_iommu_sm && ecap_smts((iommu)->ecap)) #define pasid_supported(iommu) (sm_supported(iommu) && \ diff --git a/drivers/iommu/intel/debugfs.c b/drivers/iommu/intel/debugfs.c index d927ef10641b..6e1a3f88abc8 100644 --- a/drivers/iommu/intel/debugfs.c +++ b/drivers/iommu/intel/debugfs.c @@ -342,13 +342,13 @@ static void pgtable_walk_level(struct seq_file *m, struct dma_pte *pde, } } -static int show_device_domain_translation(struct device *dev, void *data) +static int __show_device_domain_translation(struct device *dev, void *data) { - struct device_domain_info *info = dev_iommu_priv_get(dev); - struct dmar_domain *domain = info->domain; + struct dmar_domain *domain; struct seq_file *m = data; u64 path[6] = { 0 }; + domain = to_dmar_domain(iommu_get_domain_for_dev(dev)); if (!domain) return 0; @@ -359,20 +359,39 @@ static int show_device_domain_translation(struct device *dev, void *data) pgtable_walk_level(m, domain->pgd, domain->agaw + 2, 0, path); seq_putc(m, '\n'); - return 0; + /* Don't iterate */ + return 1; } -static int domain_translation_struct_show(struct seq_file *m, void *unused) +static int show_device_domain_translation(struct device *dev, void *data) { - unsigned long flags; - int ret; + struct iommu_group *group; - spin_lock_irqsave(&device_domain_lock, flags); - ret = bus_for_each_dev(&pci_bus_type, NULL, m, - show_device_domain_translation); - spin_unlock_irqrestore(&device_domain_lock, flags); + group = iommu_group_get(dev); + if (group) { + /* + * The group->mutex is held across the callback, which will + * block calls to iommu_attach/detach_group/device. Hence, + * the domain of the device will not change during traversal. + * + * All devices in an iommu group share a single domain, hence + * we only dump the domain of the first device. Even though, + * this code still possibly races with the iommu_unmap() + * interface. This could be solved by RCU-freeing the page + * table pages in the iommu_unmap() path. + */ + iommu_group_for_each_dev(group, data, + __show_device_domain_translation); + iommu_group_put(group); + } - return ret; + return 0; +} + +static int domain_translation_struct_show(struct seq_file *m, void *unused) +{ + return bus_for_each_dev(&pci_bus_type, NULL, m, + show_device_domain_translation); } DEFINE_SHOW_ATTRIBUTE(domain_translation_struct); diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 10bda4bec8fe..3b6571681bdd 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -314,7 +314,7 @@ static int iommu_skip_te_disable; #define IDENTMAP_GFX 2 #define IDENTMAP_AZALIA 4 -DEFINE_SPINLOCK(device_domain_lock); +static DEFINE_SPINLOCK(device_domain_lock); static LIST_HEAD(device_domain_list); const struct iommu_ops intel_iommu_ops; -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Lu Baolu <baolu.lu@linux.intel.com> To: iommu@lists.linux-foundation.org, iommu@lists.linux.dev Cc: Kevin Tian <kevin.tian@intel.com>, Ashok Raj <ashok.raj@intel.com>, linux-kernel@vger.kernel.org, Jacob jun Pan <jacob.jun.pan@intel.com> Subject: [PATCH v4 01/11] iommu/vt-d: debugfs: Remove device_domain_lock usage Date: Wed, 6 Jul 2022 10:55:14 +0800 [thread overview] Message-ID: <20220706025524.2904370-2-baolu.lu@linux.intel.com> (raw) In-Reply-To: <20220706025524.2904370-1-baolu.lu@linux.intel.com> The domain_translation_struct debugfs node is used to dump the DMAR page tables for the PCI devices. It potentially races with setting domains to devices. The existing code uses the global spinlock device_domain_lock to avoid the races. This removes the use of device_domain_lock outside of iommu.c by replacing it with the group mutex lock. Using the group mutex lock is cleaner and more compatible to following cleanups. Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> --- drivers/iommu/intel/iommu.h | 1 - drivers/iommu/intel/debugfs.c | 43 +++++++++++++++++++++++++---------- drivers/iommu/intel/iommu.c | 2 +- 3 files changed, 32 insertions(+), 14 deletions(-) diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h index 8285fcfa5fea..8deb745d8b36 100644 --- a/drivers/iommu/intel/iommu.h +++ b/drivers/iommu/intel/iommu.h @@ -480,7 +480,6 @@ enum { #define VTD_FLAG_SVM_CAPABLE (1 << 2) extern int intel_iommu_sm; -extern spinlock_t device_domain_lock; #define sm_supported(iommu) (intel_iommu_sm && ecap_smts((iommu)->ecap)) #define pasid_supported(iommu) (sm_supported(iommu) && \ diff --git a/drivers/iommu/intel/debugfs.c b/drivers/iommu/intel/debugfs.c index d927ef10641b..6e1a3f88abc8 100644 --- a/drivers/iommu/intel/debugfs.c +++ b/drivers/iommu/intel/debugfs.c @@ -342,13 +342,13 @@ static void pgtable_walk_level(struct seq_file *m, struct dma_pte *pde, } } -static int show_device_domain_translation(struct device *dev, void *data) +static int __show_device_domain_translation(struct device *dev, void *data) { - struct device_domain_info *info = dev_iommu_priv_get(dev); - struct dmar_domain *domain = info->domain; + struct dmar_domain *domain; struct seq_file *m = data; u64 path[6] = { 0 }; + domain = to_dmar_domain(iommu_get_domain_for_dev(dev)); if (!domain) return 0; @@ -359,20 +359,39 @@ static int show_device_domain_translation(struct device *dev, void *data) pgtable_walk_level(m, domain->pgd, domain->agaw + 2, 0, path); seq_putc(m, '\n'); - return 0; + /* Don't iterate */ + return 1; } -static int domain_translation_struct_show(struct seq_file *m, void *unused) +static int show_device_domain_translation(struct device *dev, void *data) { - unsigned long flags; - int ret; + struct iommu_group *group; - spin_lock_irqsave(&device_domain_lock, flags); - ret = bus_for_each_dev(&pci_bus_type, NULL, m, - show_device_domain_translation); - spin_unlock_irqrestore(&device_domain_lock, flags); + group = iommu_group_get(dev); + if (group) { + /* + * The group->mutex is held across the callback, which will + * block calls to iommu_attach/detach_group/device. Hence, + * the domain of the device will not change during traversal. + * + * All devices in an iommu group share a single domain, hence + * we only dump the domain of the first device. Even though, + * this code still possibly races with the iommu_unmap() + * interface. This could be solved by RCU-freeing the page + * table pages in the iommu_unmap() path. + */ + iommu_group_for_each_dev(group, data, + __show_device_domain_translation); + iommu_group_put(group); + } - return ret; + return 0; +} + +static int domain_translation_struct_show(struct seq_file *m, void *unused) +{ + return bus_for_each_dev(&pci_bus_type, NULL, m, + show_device_domain_translation); } DEFINE_SHOW_ATTRIBUTE(domain_translation_struct); diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 10bda4bec8fe..3b6571681bdd 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -314,7 +314,7 @@ static int iommu_skip_te_disable; #define IDENTMAP_GFX 2 #define IDENTMAP_AZALIA 4 -DEFINE_SPINLOCK(device_domain_lock); +static DEFINE_SPINLOCK(device_domain_lock); static LIST_HEAD(device_domain_list); const struct iommu_ops intel_iommu_ops; -- 2.25.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2022-07-06 2:59 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-07-06 2:55 [PATCH v4 00/11] iommu/vt-d: Optimize the use of locks Lu Baolu 2022-07-06 2:55 ` Lu Baolu 2022-07-06 2:55 ` Lu Baolu [this message] 2022-07-06 2:55 ` [PATCH v4 01/11] iommu/vt-d: debugfs: Remove device_domain_lock usage Lu Baolu [not found] ` <849557ab-9c1b-a2ff-6fc6-6564f38d1187@linux.intel.com> 2022-07-07 9:18 ` Baolu Lu 2022-07-06 2:55 ` [PATCH v4 02/11] iommu/vt-d: Remove clearing translation data in disable_dmar_iommu() Lu Baolu 2022-07-06 2:55 ` Lu Baolu 2022-07-07 3:03 ` Tian, Kevin 2022-07-06 2:55 ` [PATCH v4 03/11] iommu/vt-d: Use pci_get_domain_bus_and_slot() in pgtable_walk() Lu Baolu 2022-07-06 2:55 ` Lu Baolu 2022-07-06 2:55 ` [PATCH v4 04/11] iommu/vt-d: Unnecessary spinlock for root table alloc and free Lu Baolu 2022-07-06 2:55 ` Lu Baolu 2022-07-06 2:55 ` [PATCH v4 05/11] iommu/vt-d: Replace spin_lock_irqsave() with spin_lock() Lu Baolu 2022-07-06 2:55 ` Lu Baolu 2022-07-06 2:55 ` [PATCH v4 06/11] iommu/vt-d: Acquiring lock in domain ID allocation helpers Lu Baolu 2022-07-06 2:55 ` Lu Baolu 2022-07-06 2:55 ` [PATCH v4 07/11] iommu/vt-d: Acquiring lock in pasid manipulation helpers Lu Baolu 2022-07-06 2:55 ` Lu Baolu 2022-07-06 2:55 ` [PATCH v4 08/11] iommu/vt-d: Check device list of domain in domain free path Lu Baolu 2022-07-06 2:55 ` Lu Baolu 2022-07-06 2:55 ` [PATCH v4 09/11] iommu/vt-d: Fold __dmar_remove_one_dev_info() into its caller Lu Baolu 2022-07-06 2:55 ` Lu Baolu 2022-07-06 2:55 ` [PATCH v4 10/11] iommu/vt-d: Use device_domain_lock accurately Lu Baolu 2022-07-06 2:55 ` Lu Baolu 2022-07-06 2:55 ` [PATCH v4 11/11] iommu/vt-d: Convert global spinlock into per domain lock Lu Baolu 2022-07-06 2:55 ` Lu Baolu
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