iommu/vt-d: Implement SVM_FLAG_PRIVATE_PASID to allocate unique PASIDs

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

3 files changed, 16 insertions, 2 deletions

diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index 006e95dd64ae..89d4d47d0ab3 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -285,11 +285,12 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
                 pasid_max = 1 << 20;
 
         mutex_lock(&pasid_mutex);
-        if (pasid) {
+        if (pasid && !(flags & SVM_FLAG_PRIVATE_PASID)) {
                 int i;
 
                 idr_for_each_entry(&iommu->pasid_idr, svm, i) {
-                        if (svm->mm != current->mm)
+                        if (svm->mm != current->mm ||
+                            (svm->flags & SVM_FLAG_PRIVATE_PASID))
                                 continue;
 
                         if (svm->pasid >= pasid_max) {
@@ -355,6 +356,7 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
                 svm->pasid = ret;
                 svm->notifier.ops = &intel_mmuops;
                 svm->mm = get_task_mm(current);
+                svm->flags = flags;
                 INIT_LIST_HEAD_RCU(&svm->devs);
                 ret = -ENOMEM;
                 if (!svm->mm || (ret = mmu_notifier_register(&svm->notifier, svm->mm))) {
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 57be14fce640..821273ca4873 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -489,6 +489,7 @@ struct intel_svm {
         struct mmu_notifier notifier;
         struct mm_struct *mm;
         struct intel_iommu *iommu;
+        int flags;
         int pasid;
         struct list_head devs;
 };
diff --git a/include/linux/intel-svm.h b/include/linux/intel-svm.h
index 239f8a13a332..dd94ab45a4db 100644
--- a/include/linux/intel-svm.h
+++ b/include/linux/intel-svm.h
@@ -31,6 +31,17 @@ struct svm_dev_ops {
 #define SVM_REQ_EXEC    (1<<1)
 #define SVM_REQ_PRIV    (1<<0)
 
+
+/*
+ * The SVM_FLAG_PRIVATE_PASID flag requests a PASID which is *not* the "main"
+ * PASID for the current process. Even if a PASID already exists, a new one
+ * will be allocated. And the PASID allocated with SVM_FLAG_PRIVATE_PASID
+ * will not be given to subsequent callers. This facility allows a driver to
+ * disambiguate between multiple device contexts which access the same MM,
+ * if there is no other way to do so. It should be used sparingly, if at all.
+ */
+#define SVM_FLAG_PRIVATE_PASID  (1<<0)
+
 /**
  * intel_svm_bind_mm() - Bind the current process to a PASID
  * @dev:        Device to be granted acccess