Using a vfio device, a notifier block can be registered to receive
select device events. Notifiers can only be registered for contained
devices, ie. they are available through a user context. Registration
of a notifier increments the reference to that container context
therefore notifiers must minimally respond to the release event by
asynchronously removing notifiers.
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
drivers/vfio/Kconfig | 1 +
drivers/vfio/vfio.c | 35 +++++++++++++++++++++++++++++++++++
include/linux/vfio.h | 9 +++++++++
3 files changed, 45 insertions(+)
diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
index 90c0525b1e0c..9a67675c9b6c 100644
--- a/drivers/vfio/Kconfig
+++ b/drivers/vfio/Kconfig
@@ -23,6 +23,7 @@ menuconfig VFIO
tristate "VFIO Non-Privileged userspace driver framework"
select IOMMU_API
select VFIO_IOMMU_TYPE1 if (X86 || S390 || ARM || ARM64)
+ select SRCU
help
VFIO provides a framework for secure userspace device drivers.
See Documentation/driver-api/vfio.rst for more details.
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index c47895539a1a..7f6d00e54e83 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -105,6 +105,7 @@ struct vfio_device {
struct list_head group_next;
void *device_data;
struct inode *inode;
+ struct srcu_notifier_head notifier;
};
#ifdef CONFIG_VFIO_NOIOMMU
@@ -601,6 +602,7 @@ struct vfio_device *vfio_group_create_device(struct vfio_group *group,
device->ops = ops;
device->device_data = device_data;
dev_set_drvdata(dev, device);
+ srcu_init_notifier_head(&device->notifier);
/* No need to get group_lock, caller has group reference */
vfio_group_get(group);
@@ -1785,6 +1787,39 @@ static const struct file_operations vfio_device_fops = {
.mmap = vfio_device_fops_mmap,
};
+int vfio_device_register_notifier(struct vfio_device *device,
+ struct notifier_block *nb)
+{
+ int ret;
+
+ /* Container ref persists until unregister on success */
+ ret = vfio_group_add_container_user(device->group);
+ if (ret)
+ return ret;
+
+ ret = srcu_notifier_chain_register(&device->notifier, nb);
+ if (ret)
+ vfio_group_try_dissolve_container(device->group);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vfio_device_register_notifier);
+
+void vfio_device_unregister_notifier(struct vfio_device *device,
+ struct notifier_block *nb)
+{
+ if (!srcu_notifier_chain_unregister(&device->notifier, nb))
+ vfio_group_try_dissolve_container(device->group);
+}
+EXPORT_SYMBOL_GPL(vfio_device_unregister_notifier);
+
+int vfio_device_notifier_call(struct vfio_device *device,
+ enum vfio_device_notify_type event)
+{
+ return srcu_notifier_call_chain(&device->notifier, event, NULL);
+}
+EXPORT_SYMBOL_GPL(vfio_device_notifier_call);
+
/**
* External user API, exported by symbols to be linked dynamically.
*
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index dbd90d0ba713..c3ff36a7fa6f 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -62,6 +62,15 @@ extern void vfio_device_unmap_mapping_range(struct vfio_device *device,
loff_t start, loff_t len);
extern struct vfio_device *vfio_device_get_from_vma(struct vm_area_struct *vma);
extern int vfio_vma_to_pfn(struct vm_area_struct *vma, unsigned long *pfn);
+extern int vfio_device_register_notifier(struct vfio_device *device,
+ struct notifier_block *nb);
+extern void vfio_device_unregister_notifier(struct vfio_device *device,
+ struct notifier_block *nb);
+enum vfio_device_notify_type {
+ VFIO_DEVICE_RELEASE = 0,
+};
+int vfio_device_notifier_call(struct vfio_device *device,
+ enum vfio_device_notify_type event);
/* events for the backend driver notify callback */
enum vfio_iommu_notify_type {
