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| author | Lu Baolu <baolu.lu@linux.intel.com> | 2022-09-11 11:18:45 +0800 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2022-09-11 08:19:24 +0200 |
| commit | 9cd4f1434479f1ac25c440c421fbf52069079914 (patch) | |
| tree | 9af1dd0827dafc9a02679d4cb79eedc311fa84b4 /include | |
| parent | 91c98fe7941499e4127cdc359c30841b873dd43a (diff) | |
| download | lwn-9cd4f1434479f1ac25c440c421fbf52069079914.tar.gz lwn-9cd4f1434479f1ac25c440c421fbf52069079914.zip | |
iommu/vt-d: Fix possible recursive locking in intel_iommu_init()
The global rwsem dmar_global_lock was introduced by commit 3a5670e8ac932
("iommu/vt-d: Introduce a rwsem to protect global data structures"). It
is used to protect DMAR related global data from DMAR hotplug operations.
The dmar_global_lock used in the intel_iommu_init() might cause recursive
locking issue, for example, intel_iommu_get_resv_regions() is taking the
dmar_global_lock from within a section where intel_iommu_init() already
holds it via probe_acpi_namespace_devices().
Using dmar_global_lock in intel_iommu_init() could be relaxed since it is
unlikely that any IO board must be hot added before the IOMMU subsystem is
initialized. This eliminates the possible recursive locking issue by moving
down DMAR hotplug support after the IOMMU is initialized and removing the
uses of dmar_global_lock in intel_iommu_init().
Fixes: d5692d4af08cd ("iommu/vt-d: Fix suspicious RCU usage in probe_acpi_namespace_devices()")
Reported-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/894db0ccae854b35c73814485569b634237b5538.1657034828.git.robin.murphy@arm.com
Link: https://lore.kernel.org/r/20220718235325.3952426-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/dmar.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/dmar.h b/include/linux/dmar.h index d81a51978d01..8917a32173c4 100644 --- a/include/linux/dmar.h +++ b/include/linux/dmar.h @@ -65,6 +65,7 @@ struct dmar_pci_notify_info { extern struct rw_semaphore dmar_global_lock; extern struct list_head dmar_drhd_units; +extern int intel_iommu_enabled; #define for_each_drhd_unit(drhd) \ list_for_each_entry_rcu(drhd, &dmar_drhd_units, list, \ @@ -88,7 +89,8 @@ extern struct list_head dmar_drhd_units; static inline bool dmar_rcu_check(void) { return rwsem_is_locked(&dmar_global_lock) || - system_state == SYSTEM_BOOTING; + system_state == SYSTEM_BOOTING || + (IS_ENABLED(CONFIG_INTEL_IOMMU) && !intel_iommu_enabled); } #define dmar_rcu_dereference(p) rcu_dereference_check((p), dmar_rcu_check()) |