It was used as a reference counter of an existing bond between device
and user application memory address. Commit be51b1d6bbff ("iommu/sva:
Refactoring iommu_sva_bind/unbind_device()") has added this in iommu
core. Remove it to avoid duplicate code.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20230109014955.147068-4-baolu.lu@linux.intel.com
---
drivers/iommu/intel/iommu.h | 1 -
drivers/iommu/intel/svm.c | 62 ++++++++++++++++---------------------
2 files changed, 27 insertions(+), 36 deletions(-)
@@ -762,7 +762,6 @@ struct intel_svm_dev {
struct device *dev;
struct intel_iommu *iommu;
struct iommu_sva sva;
- int users;
u16 did;
u16 sid, qdep;
};
@@ -333,13 +333,6 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
}
}
- /* Find the matching device in svm list */
- sdev = svm_lookup_device_by_dev(svm, dev);
- if (sdev) {
- sdev->users++;
- goto success;
- }
-
sdev = kzalloc(sizeof(*sdev), GFP_KERNEL);
if (!sdev) {
ret = -ENOMEM;
@@ -350,7 +343,6 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
sdev->iommu = iommu;
sdev->did = FLPT_DEFAULT_DID;
sdev->sid = PCI_DEVID(info->bus, info->devfn);
- sdev->users = 1;
sdev->sva.dev = dev;
init_rcu_head(&sdev->rcu);
if (info->ats_enabled) {
@@ -367,7 +359,7 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
goto free_sdev;
list_add_rcu(&sdev->list, &svm->devs);
-success:
+
return &sdev->sva;
free_sdev:
@@ -401,32 +393,32 @@ static int intel_svm_unbind_mm(struct device *dev, u32 pasid)
mm = svm->mm;
if (sdev) {
- sdev->users--;
- if (!sdev->users) {
- list_del_rcu(&sdev->list);
- /* Flush the PASID cache and IOTLB for this device.
- * Note that we do depend on the hardware *not* using
- * the PASID any more. Just as we depend on other
- * devices never using PASIDs that they have no right
- * to use. We have a *shared* PASID table, because it's
- * large and has to be physically contiguous. So it's
- * hard to be as defensive as we might like. */
- intel_pasid_tear_down_entry(iommu, dev,
- svm->pasid, false);
- intel_svm_drain_prq(dev, svm->pasid);
- kfree_rcu(sdev, rcu);
-
- if (list_empty(&svm->devs)) {
- if (svm->notifier.ops)
- mmu_notifier_unregister(&svm->notifier, mm);
- pasid_private_remove(svm->pasid);
- /* We mandate that no page faults may be outstanding
- * for the PASID when intel_svm_unbind_mm() is called.
- * If that is not obeyed, subtle errors will happen.
- * Let's make them less subtle... */
- memset(svm, 0x6b, sizeof(*svm));
- kfree(svm);
- }
+ list_del_rcu(&sdev->list);
+ /*
+ * Flush the PASID cache and IOTLB for this device.
+ * Note that we do depend on the hardware *not* using
+ * the PASID any more. Just as we depend on other
+ * devices never using PASIDs that they have no right
+ * to use. We have a *shared* PASID table, because it's
+ * large and has to be physically contiguous. So it's
+ * hard to be as defensive as we might like.
+ */
+ intel_pasid_tear_down_entry(iommu, dev, svm->pasid, false);
+ intel_svm_drain_prq(dev, svm->pasid);
+ kfree_rcu(sdev, rcu);
+
+ if (list_empty(&svm->devs)) {
+ if (svm->notifier.ops)
+ mmu_notifier_unregister(&svm->notifier, mm);
+ pasid_private_remove(svm->pasid);
+ /*
+ * We mandate that no page faults may be outstanding
+ * for the PASID when intel_svm_unbind_mm() is called.
+ * If that is not obeyed, subtle errors will happen.
+ * Let's make them less subtle...
+ */
+ memset(svm, 0x6b, sizeof(*svm));
+ kfree(svm);
}
}
out: