[PATCH v4 04/26] iommu/sva: Search mm by PASID

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>

The fault handler will need to find an mm given its PASID. This is the
reason we have an IDR for storing address spaces, so hook it up.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 drivers/iommu/iommu-sva.c | 19 +++++++++++++++++++
 include/linux/iommu.h     |  9 +++++++++
 2 files changed, 28 insertions(+)

diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index 64f1d1c82383..bfd0c477f290 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -559,3 +559,22 @@ int iommu_sva_get_pasid_generic(struct iommu_sva *handle)
 	return pasid;
 }
 EXPORT_SYMBOL_GPL(iommu_sva_get_pasid_generic);
+
+/* ioasid wants a void * argument */
+static bool __mmget_not_zero(void *mm)
+{
+	return mmget_not_zero(mm);
+}
+
+/**
+ * iommu_sva_find() - Find mm associated to the given PASID
+ * @pasid: Process Address Space ID assigned to the mm
+ *
+ * Returns the mm corresponding to this PASID, or an error if not found. A
+ * reference to the mm is taken, and must be released with mmput().
+ */
+struct mm_struct *iommu_sva_find(int pasid)
+{
+	return ioasid_find(&shared_pasid, pasid, __mmget_not_zero);
+}
+EXPORT_SYMBOL_GPL(iommu_sva_find);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index e7bc47ba24f8..e52a8731e7a9 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -1091,6 +1091,15 @@ void iommu_debugfs_setup(void);
 static inline void iommu_debugfs_setup(void) {}
 #endif
 
+#ifdef CONFIG_IOMMU_SVA
+extern struct mm_struct *iommu_sva_find(int pasid);
+#else /* !CONFIG_IOMMU_SVA */
+static inline struct mm_struct *iommu_sva_find(int pasid)
+{
+	return NULL;
+}
+#endif /* !CONFIG_IOMMU_SVA */
+
 #ifdef CONFIG_IOMMU_PAGE_FAULT
 extern int iommu_queue_iopf(struct iommu_fault *fault, void *cookie);
 
-- 
2.25.0

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