[PATCH RFC 08/15] vfio/mdev: Add a member for iommu domain in mdev_device

[Dave Jiang <dave.jiang@intel.com>]

From: Lu Baolu <baolu.lu@linux.intel.com>

This adds a member to save iommu domain in mdev_device
structure. Whenever an iommu domain is attached to the
mediated device, it must be save here so that a VDCM
(Virtual Device Control Module) could retreive it.

Below member is added in struct mdev_device:
* iommu_domain
  - A place to save the iommu domain attached to this
    mdev.

Below helpers are added to set and get iommu domain in
struct mdev_device.
* mdev_set/get_iommu_domain(domain)
  - A iommu domain which has been attached to the iommu
    device in order to protect and isolate the mediated
    device will be kept in the mdev data structure and
    could be retrieved later.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Liu Yi L <yi.l.liu@intel.com>
Suggested-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/vfio/mdev/mdev_core.c    |   16 ++++++++++++++++
 drivers/vfio/mdev/mdev_private.h |    1 +
 include/linux/mdev.h             |   10 ++++++++++
 3 files changed, 27 insertions(+)

diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index cecc6a6bdbef..15863cf83f3f 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -410,6 +410,22 @@ struct device *mdev_get_iommu_device(struct device *dev)
 }
 EXPORT_SYMBOL(mdev_get_iommu_device);
 
+void mdev_set_iommu_domain(struct device *dev, void *domain)
+{
+	struct mdev_device *mdev = to_mdev_device(dev);
+
+	mdev->iommu_domain = domain;
+}
+EXPORT_SYMBOL(mdev_set_iommu_domain);
+
+void *mdev_get_iommu_domain(struct device *dev)
+{
+	struct mdev_device *mdev = to_mdev_device(dev);
+
+	return mdev->iommu_domain;
+}
+EXPORT_SYMBOL(mdev_get_iommu_domain);
+
 static int __init mdev_init(void)
 {
 	return mdev_bus_register();
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index c21f1305a76b..c97478b22a02 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -32,6 +32,7 @@ struct mdev_device {
 	struct list_head next;
 	struct kobject *type_kobj;
 	struct device *iommu_device;
+	void *iommu_domain;
 	bool active;
 };
 
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index fa2344e239ef..0d66daaecc67 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -26,6 +26,16 @@ int mdev_set_iommu_device(struct device *dev, struct device *iommu_device);
 
 struct device *mdev_get_iommu_device(struct device *dev);
 
+/*
+ * Called by vfio iommu modules to save the iommu domain after a domain being
+ * attached to the mediated device. The vDCM (virtual device control module)
+ * could call mdev_get_iommu_domain() to retrieve an auxiliary domain attached
+ * to an mdev.
+ */
+void mdev_set_iommu_domain(struct device *dev, void *domain);
+
+void *mdev_get_iommu_domain(struct device *dev);
+
 /**
  * struct mdev_parent_ops - Structure to be registered for each parent device to
  * register the device to mdev module.