[PATCH 06/17] iommu/vt-d: Remove unnecessary checks in iopf disabling path

Lu Baolu
2023-04-11T06:49:50Z

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
---
drivers/iommu/intel/iommu.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index cd3a3c4b5e64..c771233d6f2a 100644
--- 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
--
2.34.1