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...@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
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