iommu/vt-d: Remove clearing translation data in disable_dmar_iommu()

The disable_dmar_iommu() is called when IOMMU initialization fails or
the IOMMU is hot-removed from the system. In both cases, there is no
need to clear the IOMMU translation data structures for devices.

On the initialization path, the device probing only happens after the
IOMMU is initialized successfully, hence there're no translation data
structures.

On the hot-remove path, there is no real use case where the IOMMU is
hot-removed, but the devices that it manages are still alive in the
system. The translation data structures were torn down during device
release, hence there's no need to repeat it in IOMMU hot-remove path
either. This removes the unnecessary code and only leaves a check.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220706025524.2904370-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 3b6571681bdd939695cbee48f83272ebb9b8da57..43aaec5bdd84945a4a0060462bb90ca4f0e33714 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1716,23 +1716,16 @@ static int iommu_init_domains(struct intel_iommu *iommu)
 
 static void disable_dmar_iommu(struct intel_iommu *iommu)
 {
-       struct device_domain_info *info, *tmp;
-       unsigned long flags;
-
        if (!iommu->domain_ids)
                return;
 
-       spin_lock_irqsave(&device_domain_lock, flags);
-       list_for_each_entry_safe(info, tmp, &device_domain_list, global) {
-               if (info->iommu != iommu)
-                       continue;
-
-               if (!info->dev || !info->domain)
-                       continue;
-
-               __dmar_remove_one_dev_info(info);
-       }
-       spin_unlock_irqrestore(&device_domain_lock, flags);
+       /*
+        * All iommu domains must have been detached from the devices,
+        * hence there should be no domain IDs in use.
+        */
+       if (WARN_ON(bitmap_weight(iommu->domain_ids, cap_ndoms(iommu->cap))
+                   > NUM_RESERVED_DID))
+               return;
 
        if (iommu->gcmd & DMA_GCMD_TE)
                iommu_disable_translation(iommu);

diff --git a/drivers/iommu/intel/pasid.h b/drivers/iommu/intel/pasid.h
index bf5b937848b4195239c99ee5dbc6161cfc3cad35..20c54e50f533c758a981ed7a39f50e532b393cc7 100644 (file)
--- a/drivers/iommu/intel/pasid.h
+++ b/drivers/iommu/intel/pasid.h
@@ -39,6 +39,7 @@
  * only and pass-through transfer modes.
  */
 #define FLPT_DEFAULT_DID               1
+#define NUM_RESERVED_DID               2
 
 /*
  * The SUPERVISOR_MODE flag indicates a first level translation which