From 0bfc6a4ea63c2adac71a824397ef48f28dbc5e47 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Tue, 30 Mar 2021 09:53:05 -0600 Subject: vfio: Split creation of a vfio_device into init and register ops This makes the struct vfio_device part of the public interface so it can be used with container_of and so forth, as is typical for a Linux subystem. This is the first step to bring some type-safety to the vfio interface by allowing the replacement of 'void *' and 'struct device *' inputs with a simple and clear 'struct vfio_device *' For now the self-allocating vfio_add_group_dev() interface is kept so each user can be updated as a separate patch. The expected usage pattern is driver core probe() function: my_device = kzalloc(sizeof(*mydevice)); vfio_init_group_dev(&my_device->vdev, dev, ops, mydevice); /* other driver specific prep */ vfio_register_group_dev(&my_device->vdev); dev_set_drvdata(dev, my_device); driver core remove() function: my_device = dev_get_drvdata(dev); vfio_unregister_group_dev(&my_device->vdev); /* other driver specific tear down */ kfree(my_device); Allowing the driver to be able to use the drvdata and vfio_device to go to/from its own data. The pattern also makes it clear that vfio_register_group_dev() must be last in the sequence, as once it is called the core code can immediately start calling ops. The init/register gap is provided to allow for the driver to do setup before ops can be called and thus avoid races. Reviewed-by: Christoph Hellwig Reviewed-by: Liu Yi L Reviewed-by: Cornelia Huck Reviewed-by: Max Gurtovoy Reviewed-by: Kevin Tian Reviewed-by: Eric Auger Signed-off-by: Jason Gunthorpe Message-Id: <3-v3-225de1400dfc+4e074-vfio1_jgg@nvidia.com> Signed-off-by: Alex Williamson --- Documentation/driver-api/vfio.rst | 31 ++++++++++++++++++------------- 1 file changed, 18 insertions(+), 13 deletions(-) (limited to 'Documentation/driver-api') diff --git a/Documentation/driver-api/vfio.rst b/Documentation/driver-api/vfio.rst index f1a4d3c3ba0b..d3a02300913a 100644 --- a/Documentation/driver-api/vfio.rst +++ b/Documentation/driver-api/vfio.rst @@ -249,18 +249,23 @@ VFIO bus driver API VFIO bus drivers, such as vfio-pci make use of only a few interfaces into VFIO core. When devices are bound and unbound to the driver, -the driver should call vfio_add_group_dev() and vfio_del_group_dev() -respectively:: - - extern int vfio_add_group_dev(struct device *dev, - const struct vfio_device_ops *ops, - void *device_data); - - extern void *vfio_del_group_dev(struct device *dev); - -vfio_add_group_dev() indicates to the core to begin tracking the -iommu_group of the specified dev and register the dev as owned by -a VFIO bus driver. The driver provides an ops structure for callbacks +the driver should call vfio_register_group_dev() and +vfio_unregister_group_dev() respectively:: + + void vfio_init_group_dev(struct vfio_device *device, + struct device *dev, + const struct vfio_device_ops *ops, + void *device_data); + int vfio_register_group_dev(struct vfio_device *device); + void vfio_unregister_group_dev(struct vfio_device *device); + +The driver should embed the vfio_device in its own structure and call +vfio_init_group_dev() to pre-configure it before going to registration. +vfio_register_group_dev() indicates to the core to begin tracking the +iommu_group of the specified dev and register the dev as owned by a VFIO bus +driver. Once vfio_register_group_dev() returns it is possible for userspace to +start accessing the driver, thus the driver should ensure it is completely +ready before calling it. The driver provides an ops structure for callbacks similar to a file operations structure:: struct vfio_device_ops { @@ -276,7 +281,7 @@ similar to a file operations structure:: }; Each function is passed the device_data that was originally registered -in the vfio_add_group_dev() call above. This allows the bus driver +in the vfio_register_group_dev() call above. This allows the bus driver an easy place to store its opaque, private data. The open/release callbacks are issued when a new file descriptor is created for a device (via VFIO_GROUP_GET_DEVICE_FD). The ioctl interface provides -- cgit v1.2.3