[PATCH v4 07/14] iommufd/viommu: Add iommufd_viommu_get_vdev_id helper

[Nicolin Chen <nicolinc@nvidia.com>]

This is a reverse search v.s. iommufd_viommu_find_dev, as drivers may want
to convert a struct device pointer (physical) to its virtual device ID for
an event injection to the user space VM.

Again, this avoids exposing more core structures to the drivers, than the
iommufd_viommu alone.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 include/linux/iommufd.h        |  8 ++++++++
 drivers/iommu/iommufd/driver.c | 20 ++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 8948b1836940..9c6ba7df3994 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -190,6 +190,8 @@ struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx,
 					     enum iommufd_object_type type);
 struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
 				       unsigned long vdev_id);
+unsigned long iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
+					 struct device *dev);
 #else /* !CONFIG_IOMMUFD_DRIVER_CORE */
 static inline struct iommufd_object *
 _iommufd_object_alloc(struct iommufd_ctx *ictx, size_t size,
@@ -203,6 +205,12 @@ iommufd_viommu_find_dev(struct iommufd_viommu *viommu, unsigned long vdev_id)
 {
 	return NULL;
 }
+
+static inline unsigned long
+iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu, struct device *dev)
+{
+	return 0;
+}
 #endif /* CONFIG_IOMMUFD_DRIVER_CORE */
 
 /*
diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
index 2d98b04ff1cb..e5d7397c0a6c 100644
--- a/drivers/iommu/iommufd/driver.c
+++ b/drivers/iommu/iommufd/driver.c
@@ -49,5 +49,25 @@ struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_viommu_find_dev, "IOMMUFD");
 
+/* Return 0 if device is not associated to the vIOMMU */
+unsigned long iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
+					 struct device *dev)
+{
+	struct iommufd_vdevice *vdev;
+	unsigned long vdev_id = 0;
+	unsigned long index;
+
+	xa_lock(&viommu->vdevs);
+	xa_for_each(&viommu->vdevs, index, vdev) {
+		if (vdev && vdev->dev == dev) {
+			vdev_id = (unsigned long)vdev->id;
+			break;
+		}
+	}
+	xa_unlock(&viommu->vdevs);
+	return vdev_id;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_viommu_get_vdev_id, "IOMMUFD");
+
 MODULE_DESCRIPTION("iommufd code shared with builtin modules");
 MODULE_LICENSE("GPL");
-- 
2.43.0