From: CQ Tang <cq.tang@xxxxxxxxx>
A driver would need to know if there are any active references to a
a PASID before cleaning up its resources. This function helps check
if there are any active users of a PASID before it can perform any
recovery on that device.
To: Joerg Roedel <joro@xxxxxxxxxx>
To: linux-kernel@xxxxxxxxxxxxxxx
To: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Jean-Phillipe Brucker <jean-philippe.brucker@xxxxxxx>
Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: CQ Tang <cq.tang@xxxxxxxxx>
Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
---
drivers/iommu/intel-svm.c | 30 ++++++++++++++++++++++++++++++
include/linux/intel-svm.h | 20 ++++++++++++++++++++
2 files changed, 50 insertions(+)
diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index 23c4276..f167c0d 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -489,6 +489,36 @@ int intel_svm_unbind_mm(struct device *dev, int pasid)
}
EXPORT_SYMBOL_GPL(intel_svm_unbind_mm);
+int intel_svm_is_pasid_valid(struct device *dev, int pasid)
+{
+ struct intel_iommu *iommu;
+ struct intel_svm *svm;
+ int ret = -EINVAL;
+
+ mutex_lock(&pasid_mutex);
+ iommu = intel_svm_device_to_iommu(dev);
+ if (!iommu || !iommu->pasid_table)
+ goto out;
+
+ svm = idr_find(&iommu->pasid_idr, pasid);
+ if (!svm)
+ goto out;
+
+ /* init_mm is used in this case */
+ if (!svm->mm)
+ ret = 1;
+ else if (atomic_read(&svm->mm->mm_users) > 0)
+ ret = 1;
+ else
+ ret = 0;
+
+ out:
+ mutex_unlock(&pasid_mutex);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(intel_svm_is_pasid_valid);
+
/* Page request queue descriptor */
struct page_req_dsc {
u64 srr:1;
diff --git a/include/linux/intel-svm.h b/include/linux/intel-svm.h
index 3c25794..99bc5b3 100644
--- a/include/linux/intel-svm.h
+++ b/include/linux/intel-svm.h
@@ -102,6 +102,21 @@ extern int intel_svm_bind_mm(struct device *dev, int *pasid, int flags,
*/
extern int intel_svm_unbind_mm(struct device *dev, int pasid);
+/**
+ * intel_svm_is_pasid_valid() - check if pasid is valid
+ * @dev: Device for which PASID was allocated
+ * @pasid: PASID value to be checked
+ *
+ * This function checks if the specified pasid is still valid. A
+ * valid pasid means the backing mm is still having a valid user.
+ * For kernel callers init_mm is always valid. for other mm, if mm->mm_users
+ * is non-zero, it is valid.
+ *
+ * returns -EINVAL if invalid pasid, 0 if pasid ref count is invalid
+ * 1 if pasid is valid.
+ */
+extern int intel_svm_is_pasid_valid(struct device *dev, int pasid);
+
#else /* CONFIG_INTEL_IOMMU_SVM */
static inline int intel_svm_bind_mm(struct device *dev, int *pasid,
@@ -114,6 +129,11 @@ static inline int intel_svm_unbind_mm(struct device *dev, int pasid)
{
BUG();
}
+
+static int intel_svm_is_pasid_valid(struct device *dev, int pasid)
+{
+ return -EINVAL;
+}
#endif /* CONFIG_INTEL_IOMMU_SVM */
#define intel_svm_available(dev) (!intel_svm_bind_mm((dev), NULL, 0, NULL))
--
2.7.4
