kernel/linux.git/drivers/vfio/group.c, branch v6.12.80

vfio: Fix unbalanced vfio_df_close call in no-iommu mode

2025-08-15T10:14:02+00:00

[ Upstream commit b25e271b377999191b12f0afbe1861edcf57e3fe ] For devices with no-iommu enabled in IOMMUFD VFIO compat mode, the group open path skips vfio_df_open(), leaving open_count at 0. This causes a warning in vfio_assert_device_open(device) when vfio_df_close() is called during group close. The correct behavior is to skip only the IOMMUFD bind in the device open path for no-iommu devices. Commit 6086efe73498 omitted vfio_df_open(), which was too broad. This patch restores the previous behavior, ensuring the vfio_df_open is called in the group open path. Fixes: 6086efe73498 ("vfio-iommufd: Move noiommu compat validation out of vfio_iommufd_bind()") Suggested-by: Alex Williamson Suggested-by: Jason Gunthorpe Signed-off-by: Jacob Pan Reviewed-by: Jason Gunthorpe Link: https://lore.kernel.org/r/20250618234618.1910456-1-jacob.pan@linux.microsoft.com Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin

introduce fd_file(), convert all accessors to it.

2024-08-13T02:00:43+00:00

For any changes of struct fd representation we need to turn existing accesses to fields into calls of wrappers. Accesses to struct fd::flags are very few (3 in linux/file.h, 1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in explicit initializers). Those can be dealt with in the commit converting to new layout; accesses to struct fd::file are too many for that. This commit converts (almost) all of f.file to fd_file(f). It's not entirely mechanical ('file' is used as a member name more than just in struct fd) and it does not even attempt to distinguish the uses in pointer context from those in boolean context; the latter will be eventually turned into a separate helper (fd_empty()). NOTE: mass conversion to fd_empty(), tempting as it might be, is a bad idea; better do that piecewise in commit that convert from fdget...() to CLASS(...). [conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c caught by git; fs/stat.c one got caught by git grep] [fs/xattr.c conflict] Reviewed-by: Christian Brauner Signed-off-by: Al Viro

vfio: Create vfio_fs_type with inode per device

2024-05-31T21:15:51+00:00

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: Jason Gunthorpe Reviewed-by: Jason Gunthorpe Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/20240530045236.1005864-2-alex.williamson@redhat.com Signed-off-by: Alex Williamson

vfio: Move the IOMMU_CAP_CACHE_COHERENCY check in __vfio_register_dev()

2023-07-25T16:20:41+00:00

The IOMMU_CAP_CACHE_COHERENCY check only applies to the physical devices that are IOMMU-backed. But it is now in the group code. If want to compile vfio_group infrastructure out, this check needs to be moved out of the group code. Another reason for this change is to fail the device registration for the physical devices that do not have IOMMU if the group code is not compiled as the cdev interface does not support such devices. Suggested-by: Jason Gunthorpe Reviewed-by: Jason Gunthorpe Tested-by: Zhenzhong Duan Tested-by: Yanting Jiang Signed-off-by: Yi Liu Link: https://lore.kernel.org/r/20230718135551.6592-25-yi.l.liu@intel.com Signed-off-by: Alex Williamson

vfio: Test kvm pointer in _vfio_device_get_kvm_safe()

2023-07-25T16:19:45+00:00

This saves some lines when adding the kvm get logic for the vfio_device cdev path. This also renames _vfio_device_get_kvm_safe() to be vfio_device_get_kvm_safe(). Suggested-by: Jason Gunthorpe Reviewed-by: Jason Gunthorpe Tested-by: Zhenzhong Duan Tested-by: Yanting Jiang Signed-off-by: Yi Liu Link: https://lore.kernel.org/r/20230718135551.6592-20-yi.l.liu@intel.com Signed-off-by: Alex Williamson

vfio-iommufd: Split bind/attach into two steps

2023-07-25T16:19:04+00:00

This aligns the bind/attach logic with the coming vfio device cdev support. Reviewed-by: Kevin Tian Reviewed-by: Jason Gunthorpe Tested-by: Terrence Xu Tested-by: Nicolin Chen Tested-by: Matthew Rosato Tested-by: Yanting Jiang Tested-by: Shameer Kolothum Tested-by: Zhenzhong Duan Signed-off-by: Yi Liu Link: https://lore.kernel.org/r/20230718135551.6592-12-yi.l.liu@intel.com Signed-off-by: Alex Williamson

vfio-iommufd: Move noiommu compat validation out of vfio_iommufd_bind()

2023-07-25T16:19:01+00:00

This moves the noiommu compat validation logic into vfio_df_group_open(). This is more consistent with what will be done in vfio device cdev path. Reviewed-by: Kevin Tian Reviewed-by: Jason Gunthorpe Tested-by: Terrence Xu Tested-by: Nicolin Chen Tested-by: Matthew Rosato Tested-by: Yanting Jiang Tested-by: Shameer Kolothum Tested-by: Zhenzhong Duan Signed-off-by: Yi Liu Link: https://lore.kernel.org/r/20230718135551.6592-11-yi.l.liu@intel.com Signed-off-by: Alex Williamson

vfio: Make vfio_df_open() single open for device cdev path

2023-07-25T16:18:57+00:00

VFIO group has historically allowed multi-open of the device FD. This was made secure because the "open" was executed via an ioctl to the group FD which is itself only single open. However, no known use of multiple device FDs today. It is kind of a strange thing to do because new device FDs can naturally be created via dup(). When we implement the new device uAPI (only used in cdev path) there is no natural way to allow the device itself from being multi-opened in a secure manner. Without the group FD we cannot prove the security context of the opener. Thus, when moving to the new uAPI we block the ability of opening a device multiple times. Given old group path still allows it we store a vfio_group pointer in struct vfio_device_file to differentiate. Reviewed-by: Kevin Tian Reviewed-by: Jason Gunthorpe Reviewed-by: Eric Auger Tested-by: Terrence Xu Tested-by: Nicolin Chen Tested-by: Matthew Rosato Tested-by: Yanting Jiang Tested-by: Shameer Kolothum Tested-by: Zhenzhong Duan Signed-off-by: Yi Liu Link: https://lore.kernel.org/r/20230718135551.6592-10-yi.l.liu@intel.com Signed-off-by: Alex Williamson

vfio: Add cdev_device_open_cnt to vfio_group

2023-07-25T16:18:54+00:00

This is for counting the devices that are opened via the cdev path. This count is increased and decreased by the cdev path. The group path checks it to achieve exclusion with the cdev path. With this, only one path (group path or cdev path) will claim DMA ownership. This avoids scenarios in which devices within the same group may be opened via different paths. Reviewed-by: Kevin Tian Reviewed-by: Jason Gunthorpe Reviewed-by: Eric Auger Tested-by: Terrence Xu Tested-by: Nicolin Chen Tested-by: Matthew Rosato Tested-by: Yanting Jiang Tested-by: Shameer Kolothum Tested-by: Zhenzhong Duan Signed-off-by: Yi Liu Link: https://lore.kernel.org/r/20230718135551.6592-9-yi.l.liu@intel.com Signed-off-by: Alex Williamson

vfio: Block device access via device fd until device is opened

2023-07-25T16:18:50+00:00

Allow the vfio_device file to be in a state where the device FD is opened but the device cannot be used by userspace (i.e. its .open_device() hasn't been called). This inbetween state is not used when the device FD is spawned from the group FD, however when we create the device FD directly by opening a cdev it will be opened in the blocked state. The reason for the inbetween state is that userspace only gets a FD but doesn't gain access permission until binding the FD to an iommufd. So in the blocked state, only the bind operation is allowed. Completing bind will allow user to further access the device. This is implemented by adding a flag in struct vfio_device_file to mark the blocked state and using a simple smp_load_acquire() to obtain the flag value and serialize all the device setup with the thread accessing this device. Following this lockless scheme, it can safely handle the device FD unbound->bound but it cannot handle bound->unbound. To allow this we'd need to add a lock on all the vfio ioctls which seems costly. So once device FD is bound, it remains bound until the FD is closed. Suggested-by: Jason Gunthorpe Reviewed-by: Kevin Tian Reviewed-by: Jason Gunthorpe Reviewed-by: Eric Auger Tested-by: Terrence Xu Tested-by: Nicolin Chen Tested-by: Matthew Rosato Tested-by: Yanting Jiang Tested-by: Shameer Kolothum Tested-by: Zhenzhong Duan Signed-off-by: Yi Liu Link: https://lore.kernel.org/r/20230718135551.6592-8-yi.l.liu@intel.com Signed-off-by: Alex Williamson