From: Lu Baolu <baolu.lu@linux.intel.com>
To: Joerg Roedel <joro@8bytes.org>, Kevin Tian <kevin.tian@intel.com>,
Ashok Raj <ashok.raj@intel.com>,
Christoph Hellwig <hch@infradead.org>,
Jason Gunthorpe <jgg@nvidia.com>
Cc: Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Liu Yi L <yi.l.liu@intel.com>,
Jacob jun Pan <jacob.jun.pan@intel.com>,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
Lu Baolu <baolu.lu@linux.intel.com>
Subject: [PATCH v2 01/12] iommu/vt-d: debugfs: Remove device_domain_lock usage
Date: Tue, 14 Jun 2022 10:51:26 +0800 [thread overview]
Message-ID: <20220614025137.1632762-2-baolu.lu@linux.intel.com> (raw)
In-Reply-To: <20220614025137.1632762-1-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 a global spinlock device_domain_lock to
avoid the races, but this is problematical as this lock is only used to
protect the device tracking lists of each domain.
This replaces device_domain_lock with group->mutex to protect page tables
from setting a new domain. This also makes device_domain_lock static as
it is now only used inside the file.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/intel/iommu.h | 1 -
drivers/iommu/intel/debugfs.c | 49 +++++++++++++++++++++++++----------
drivers/iommu/intel/iommu.c | 2 +-
3 files changed, 36 insertions(+), 16 deletions(-)
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index a22adfbdf870..8a6d64d726c0 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..5ebfe32265d5 100644
--- a/drivers/iommu/intel/debugfs.c
+++ b/drivers/iommu/intel/debugfs.c
@@ -342,15 +342,23 @@ static void pgtable_walk_level(struct seq_file *m, struct dma_pte *pde,
}
}
-static int show_device_domain_translation(struct device *dev, void *data)
+struct show_domain_opaque {
+ struct device *dev;
+ struct seq_file *m;
+};
+
+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 seq_file *m = data;
+ struct show_domain_opaque *opaque = data;
+ struct device_domain_info *info;
+ struct seq_file *m = opaque->m;
+ struct dmar_domain *domain;
u64 path[6] = { 0 };
- if (!domain)
+ if (dev != opaque->dev)
return 0;
+ info = dev_iommu_priv_get(dev);
+ domain = info->domain;
seq_printf(m, "Device %s @0x%llx\n", dev_name(dev),
(u64)virt_to_phys(domain->pgd));
@@ -359,20 +367,33 @@ 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;
+ 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 show_domain_opaque opaque = {dev, data};
+ 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.
+ */
+ iommu_group_for_each_dev(group, &opaque,
+ __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 19024dc52735..a39d72a9d1cf 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);
/*
--
2.25.1
next prev parent reply other threads:[~2022-06-14 3:00 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-14 2:51 [PATCH v2 00/12] iommu/vt-d: Optimize the use of locks Lu Baolu
2022-06-14 2:51 ` Lu Baolu [this message]
2022-06-14 6:43 ` [PATCH v2 01/12] iommu/vt-d: debugfs: Remove device_domain_lock usage Tian, Kevin
2022-06-14 7:15 ` Baolu Lu
2022-06-15 1:53 ` Baolu Lu
2022-06-15 6:13 ` Tian, Kevin
2022-06-15 13:02 ` Baolu Lu
2022-06-14 2:51 ` [PATCH v2 02/12] iommu/vt-d: Remove for_each_device_domain() Lu Baolu
2022-06-14 2:51 ` [PATCH v2 03/12] iommu/vt-d: Remove clearing translation data in disable_dmar_iommu() Lu Baolu
2022-06-14 6:49 ` Tian, Kevin
2022-06-14 7:21 ` Baolu Lu
2022-06-15 6:22 ` Tian, Kevin
2022-06-15 13:10 ` Baolu Lu
2022-06-16 4:00 ` Tian, Kevin
2022-06-14 2:51 ` [PATCH v2 04/12] iommu/vt-d: Use pci_get_domain_bus_and_slot() in pgtable_walk() Lu Baolu
2022-06-14 2:51 ` [PATCH v2 05/12] iommu/vt-d: Unnecessary spinlock for root table alloc and free Lu Baolu
2022-06-14 2:51 ` [PATCH v2 06/12] iommu/vt-d: Acquiring lock in domain ID allocation helpers Lu Baolu
2022-06-14 6:52 ` Tian, Kevin
2022-06-14 7:22 ` Baolu Lu
2022-06-14 2:51 ` [PATCH v2 07/12] iommu/vt-d: Acquiring lock in pasid manipulation helpers Lu Baolu
2022-06-14 2:51 ` [PATCH v2 08/12] iommu/vt-d: Replace spin_lock_irqsave() with spin_lock() Lu Baolu
2022-06-14 6:56 ` Tian, Kevin
2022-06-14 2:51 ` [PATCH v2 09/12] iommu/vt-d: Check device list of domain in domain free path Lu Baolu
2022-06-14 6:57 ` Tian, Kevin
2022-06-14 2:51 ` [PATCH v2 10/12] iommu/vt-d: Fold __dmar_remove_one_dev_info() into its caller Lu Baolu
2022-06-14 7:07 ` Tian, Kevin
2022-06-14 7:44 ` Baolu Lu
2022-06-14 2:51 ` [PATCH v2 11/12] iommu/vt-d: Use device_domain_lock accurately Lu Baolu
2022-06-14 7:16 ` Tian, Kevin
2022-06-14 7:47 ` Baolu Lu
2022-06-14 2:51 ` [PATCH v2 12/12] iommu/vt-d: Convert global spinlock into per domain ones Lu Baolu
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