Commit b7c5e64f authored by Alex Williamson's avatar Alex Williamson
Browse files

vfio: Create vfio_fs_type with inode per device 



By linking all the device fds we provide to userspace to an
address space through a new pseudo fs, we can use tools like
unmap_mapping_range() to zap all vmas associated with a device.

Suggested-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20240530045236.1005864-2-alex.williamson@redhat.com


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 1613e604

drivers/vfio/device_cdev.c

+7 −0
Original line number Diff line number Diff line
@@ -39,6 +39,13 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep) 


	filep->private_data = df;



	/*

	 * Use the pseudo fs inode on the device to link all mmaps

	 * to the same address space, allowing us to unmap all vmas

	 * associated to this device using unmap_mapping_range().

	 */

	filep->f_mapping = device->inode->i_mapping;



	return 0;



err_put_registration:

drivers/vfio/group.c

+7 −0
Original line number Diff line number Diff line
@@ -286,6 +286,13 @@ static struct file *vfio_device_open_file(struct vfio_device *device) 
	 */

	filep->f_mode |= (FMODE_PREAD | FMODE_PWRITE);



	/*

	 * Use the pseudo fs inode on the device to link all mmaps

	 * to the same address space, allowing us to unmap all vmas

	 * associated to this device using unmap_mapping_range().

	 */

	filep->f_mapping = device->inode->i_mapping;



	if (device->group->type == VFIO_NO_IOMMU)

		dev_warn(device->dev, "vfio-noiommu device opened by user "

			 "(%s:%d)\n", current->comm, task_pid_nr(current));

drivers/vfio/vfio_main.c

+44 −0
Original line number Diff line number Diff line
@@ -22,8 +22,10 @@ 
#include <linux/list.h>

#include <linux/miscdevice.h>

#include <linux/module.h>

#include <linux/mount.h>

#include <linux/mutex.h>

#include <linux/pci.h>

#include <linux/pseudo_fs.h>

#include <linux/rwsem.h>

#include <linux/sched.h>

#include <linux/slab.h>
@@ -43,9 +45,13 @@ 
#define DRIVER_AUTHOR	"Alex Williamson <alex.williamson@redhat.com>"

#define DRIVER_DESC	"VFIO - User Level meta-driver"



#define VFIO_MAGIC 0x5646494f /* "VFIO" */



static struct vfio {

	struct class			*device_class;

	struct ida			device_ida;

	struct vfsmount			*vfs_mount;

	int				fs_count;

} vfio;



#ifdef CONFIG_VFIO_NOIOMMU
@@ -186,6 +192,8 @@ static void vfio_device_release(struct device *dev) 
	if (device->ops->release)

		device->ops->release(device);



	iput(device->inode);

	simple_release_fs(&vfio.vfs_mount, &vfio.fs_count);

	kvfree(device);

}
@@ -228,6 +236,34 @@ struct vfio_device *_vfio_alloc_device(size_t size, struct device *dev, 
}

EXPORT_SYMBOL_GPL(_vfio_alloc_device);



static int vfio_fs_init_fs_context(struct fs_context *fc)

{

	return init_pseudo(fc, VFIO_MAGIC) ? 0 : -ENOMEM;

}



static struct file_system_type vfio_fs_type = {

	.name = "vfio",

	.owner = THIS_MODULE,

	.init_fs_context = vfio_fs_init_fs_context,

	.kill_sb = kill_anon_super,

};



static struct inode *vfio_fs_inode_new(void)

{

	struct inode *inode;

	int ret;



	ret = simple_pin_fs(&vfio_fs_type, &vfio.vfs_mount, &vfio.fs_count);

	if (ret)

		return ERR_PTR(ret);



	inode = alloc_anon_inode(vfio.vfs_mount->mnt_sb);

	if (IS_ERR(inode))

		simple_release_fs(&vfio.vfs_mount, &vfio.fs_count);



	return inode;

}



/*

 * Initialize a vfio_device so it can be registered to vfio core.

 */
@@ -246,6 +282,11 @@ static int vfio_init_device(struct vfio_device *device, struct device *dev, 
	init_completion(&device->comp);

	device->dev = dev;

	device->ops = ops;

	device->inode = vfio_fs_inode_new();

	if (IS_ERR(device->inode)) {

		ret = PTR_ERR(device->inode);

		goto out_inode;

	}



	if (ops->init) {

		ret = ops->init(device);
@@ -260,6 +301,9 @@ static int vfio_init_device(struct vfio_device *device, struct device *dev, 
	return 0;



out_uninit:

	iput(device->inode);

	simple_release_fs(&vfio.vfs_mount, &vfio.fs_count);

out_inode:

	vfio_release_device_set(device);

	ida_free(&vfio.device_ida, device->index);

	return ret;

include/linux/vfio.h

+1 −0
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ struct vfio_device { 
	struct completion comp;

	struct iommufd_access *iommufd_access;

	void (*put_kvm)(struct kvm *kvm);

	struct inode *inode;

#if IS_ENABLED(CONFIG_IOMMUFD)

	struct iommufd_device *iommufd_device;

	u8 iommufd_attached:1;