[v6 1/3] vfio: vfio_register_notifier: classify iommu notifier

[Jike Song <jike.song@intel.com>]

Currently vfio_register_notifier assumes that there is only one
notifier chain, which is in vfio_iommu. However, the user might
also be interested in events other than vfio_iommu, for example,
vfio_group. Refactor vfio_{un}register_notifier implementation
to make it feasible.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Kirti Wankhede <kwankhede@nvidia.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Jike Song <jike.song@intel.com>
---
 drivers/vfio/vfio.c  | 87 +++++++++++++++++++++++++++++++++++++++-------------
 include/linux/vfio.h | 16 ++++++++--
 2 files changed, 78 insertions(+), 25 deletions(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index c815067..ec62bec 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -2007,23 +2007,24 @@ int vfio_unpin_pages(struct device *dev, unsigned long *user_pfn, int npage)
 }
 EXPORT_SYMBOL(vfio_unpin_pages);
 
-int vfio_register_notifier(struct device *dev, struct notifier_block *nb)
+static int vfio_register_iommu_notifier(struct vfio_group *group,
+					unsigned long *events,
+					struct notifier_block *nb)
 {
 	struct vfio_container *container;
-	struct vfio_group *group;
 	struct vfio_iommu_driver *driver;
 	int ret;
 
-	if (!dev || !nb)
-		return -EINVAL;
+	/* clear known events */
+	*events &= ~VFIO_IOMMU_NOTIFY_DMA_UNMAP;
 
-	group = vfio_group_get_from_dev(dev);
-	if (IS_ERR(group))
-		return PTR_ERR(group);
+	/* refuse to register if still events remaining */
+	if (*events)
+		return -EINVAL;
 
 	ret = vfio_group_add_container_user(group);
 	if (ret)
-		goto err_register_nb;
+		return -EINVAL;
 
 	container = group->container;
 	down_read(&container->group_lock);
@@ -2037,29 +2038,19 @@ int vfio_register_notifier(struct device *dev, struct notifier_block *nb)
 	up_read(&container->group_lock);
 	vfio_group_try_dissolve_container(group);
 
-err_register_nb:
-	vfio_group_put(group);
 	return ret;
 }
-EXPORT_SYMBOL(vfio_register_notifier);
 
-int vfio_unregister_notifier(struct device *dev, struct notifier_block *nb)
+static int vfio_unregister_iommu_notifier(struct vfio_group *group,
+					  struct notifier_block *nb)
 {
 	struct vfio_container *container;
-	struct vfio_group *group;
 	struct vfio_iommu_driver *driver;
 	int ret;
 
-	if (!dev || !nb)
-		return -EINVAL;
-
-	group = vfio_group_get_from_dev(dev);
-	if (IS_ERR(group))
-		return PTR_ERR(group);
-
 	ret = vfio_group_add_container_user(group);
 	if (ret)
-		goto err_unregister_nb;
+		return -EINVAL;
 
 	container = group->container;
 	down_read(&container->group_lock);
@@ -2074,7 +2065,59 @@ int vfio_unregister_notifier(struct device *dev, struct notifier_block *nb)
 	up_read(&container->group_lock);
 	vfio_group_try_dissolve_container(group);
 
-err_unregister_nb:
+	return ret;
+}
+
+int vfio_register_notifier(struct device *dev, vfio_notify_type_t type,
+			   unsigned long *events,
+			   struct notifier_block *nb)
+{
+	struct vfio_group *group;
+	int ret;
+
+	if (!dev || !nb)
+		return -EINVAL;
+	if (!events || *events == 0)
+		return -EINVAL;
+
+	group = vfio_group_get_from_dev(dev);
+	if (IS_ERR(group))
+		return PTR_ERR(group);
+
+	switch (type) {
+	case VFIO_IOMMU_NOTIFY:
+		ret = vfio_register_iommu_notifier(group, events, nb);
+		break;
+	default:
+		ret = EINVAL;
+	}
+
+	vfio_group_put(group);
+	return ret;
+}
+EXPORT_SYMBOL(vfio_register_notifier);
+
+int vfio_unregister_notifier(struct device *dev, vfio_notify_type_t type,
+			     struct notifier_block *nb)
+{
+	struct vfio_group *group;
+	int ret;
+
+	if (!dev || !nb)
+		return -EINVAL;
+
+	group = vfio_group_get_from_dev(dev);
+	if (IS_ERR(group))
+		return PTR_ERR(group);
+
+	switch (type) {
+	case VFIO_IOMMU_NOTIFY:
+		ret = vfio_unregister_iommu_notifier(group, nb);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
 	vfio_group_put(group);
 	return ret;
 }
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 15ff042..6f3ff31 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -107,14 +107,24 @@ extern int vfio_pin_pages(struct device *dev, unsigned long *user_pfn,
 extern int vfio_unpin_pages(struct device *dev, unsigned long *user_pfn,
 			    int npage);
 
-#define VFIO_IOMMU_NOTIFY_DMA_UNMAP	(1)
-
+typedef unsigned short vfio_notify_type_t;
 extern int vfio_register_notifier(struct device *dev,
+				  vfio_notify_type_t type,
+				  unsigned long *required_events,
 				  struct notifier_block *nb);
-
 extern int vfio_unregister_notifier(struct device *dev,
+				    vfio_notify_type_t type,
 				    struct notifier_block *nb);
 
+/* each type has independent events */
+enum vfio_notify_type {
+	VFIO_IOMMU_NOTIFY = (__force vfio_notify_type_t)0,
+};
+
+/* events for VFIO_IOMMU_NOTIFY */
+#define VFIO_IOMMU_NOTIFY_DMA_UNMAP	BIT(0)
+
+
 /*
  * Sub-module helpers
  */
-- 
1.9.1