iommu/vt-d: Remove unnecessary checks in iopf disabling path

iommu_unregister_device_fault_handler() and iopf_queue_remove_device()
are called after device has stopped issuing new page falut requests and
all outstanding page requests have been drained. They should never fail.
Trigger a warning if it happens unfortunately.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20230324120234.313643-7-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 cd3a3c4b5e6488a7e77e4ae68853e6b130e4dd14..c771233d6f2aef06eb0e8b72ef1fc42efc1423cf 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4707,7 +4707,6 @@ static int intel_iommu_disable_iopf(struct device *dev)
 {
        struct device_domain_info *info = dev_iommu_priv_get(dev);
        struct intel_iommu *iommu = info->iommu;
-       int ret;
 
        if (!info->pri_enabled)
                return -EINVAL;
@@ -4723,15 +4722,15 @@ static int intel_iommu_disable_iopf(struct device *dev)
        pci_disable_pri(to_pci_dev(dev));
        info->pri_enabled = 0;
 
-       ret = iommu_unregister_device_fault_handler(dev);
-       if (ret)
-               return ret;
-
-       ret = iopf_queue_remove_device(iommu->iopf_queue, dev);
-       if (ret)
-               iommu_register_device_fault_handler(dev, iommu_queue_iopf, dev);
+       /*
+        * With PRI disabled and outstanding PRQs drained, unregistering
+        * fault handler and removing device from iopf queue should never
+        * fail.
+        */
+       WARN_ON(iommu_unregister_device_fault_handler(dev));
+       WARN_ON(iopf_queue_remove_device(iommu->iopf_queue, dev));
 
-       return ret;
+       return 0;
 }
 
 static int