[v6,06/14] iommufd/viommu: Add iommufd_viommu_get_vdev_id helper

Commit Message

Nicolin Chen Jan. 25, 2025, 12:30 a.m. UTC

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.

Reviewed-by: Lu Baolu <[e-mail]>
Reviewed-by: Kevin Tian <[e-mail]>
Signed-off-by: Nicolin Chen <[e-mail]>
---
 include/linux/iommufd.h        |  9 +++++++++
 drivers/iommu/iommufd/driver.c | 24 ++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

Patch

diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 8948b1836940..05cb393aff0a 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);
+int iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
+			       struct device *dev, unsigned long *vdev_id);
 #else /* !CONFIG_IOMMUFD_DRIVER_CORE */
 static inline struct iommufd_object *
 _iommufd_object_alloc(struct iommufd_ctx *ictx, size_t size,
@@ -203,6 +205,13 @@  iommufd_viommu_find_dev(struct iommufd_viommu *viommu, unsigned long vdev_id)
 {
 	return NULL;
 }
+
+static inline int iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
+					     struct device *dev,
+					     unsigned long *vdev_id)
+{
+	return -ENOENT;
+}
 #endif /* CONFIG_IOMMUFD_DRIVER_CORE */
 
 /*
diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
index 2d98b04ff1cb..185c4fde8987 100644
--- a/drivers/iommu/iommufd/driver.c
+++ b/drivers/iommu/iommufd/driver.c
@@ -49,5 +49,29 @@  struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_viommu_find_dev, "IOMMUFD");
 
+/* Return -ENOENT if device is not associated to the vIOMMU */
+int iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
+			       struct device *dev, unsigned long *vdev_id)
+{
+	struct iommufd_vdevice *vdev;
+	unsigned long index;
+	int rc = -ENOENT;
+
+	if (WARN_ON_ONCE(!vdev_id))
+		return -EINVAL;
+
+	xa_lock(&viommu->vdevs);
+	xa_for_each(&viommu->vdevs, index, vdev) {
+		if (vdev->dev == dev) {
+			*vdev_id = (unsigned long)vdev->id;
+			rc = 0;
+			break;
+		}
+	}
+	xa_unlock(&viommu->vdevs);
+	return rc;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_viommu_get_vdev_id, "IOMMUFD");
+
 MODULE_DESCRIPTION("iommufd code shared with builtin modules");
 MODULE_LICENSE("GPL");