Commit Graph

27 Commits

Author SHA1 Message Date
Alex Williamson d10999016f vfio: Convert control interface to misc driver
This change allows us to support module auto loading using devname
support in userspace tools.  With this, /dev/vfio/vfio will always
be present and opening it will cause the vfio module to load.  This
should avoid needing to configure the system to statically load
vfio in order to get libvirt to correctly detect support for it.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-12-19 10:17:13 -07:00
Alex Williamson 5d042fbdbb vfio: Add O_CLOEXEC flag to vfio device fd
Add the default O_CLOEXEC flag for device file descriptors.  This is
generally considered a safer option as it allows the user a race free
option to decide whether file descriptors are inherited across exec,
with the default avoiding file descriptor leaks.

Reported-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-08-22 10:33:41 -06:00
Yann Droneaud a5d550703d vfio: use get_unused_fd_flags(0) instead of get_unused_fd()
Macro get_unused_fd() is used to allocate a file descriptor with
default flags. Those default flags (0) can be "unsafe":
O_CLOEXEC must be used by default to not leak file descriptor
across exec().

Instead of macro get_unused_fd(), functions anon_inode_getfd()
or get_unused_fd_flags() should be used with flags given by userspace.
If not possible, flags should be set to O_CLOEXEC to provide userspace
with a default safe behavor.

In a further patch, get_unused_fd() will be removed so that
new code start using anon_inode_getfd() or get_unused_fd_flags()
with correct flags.

This patch replaces calls to get_unused_fd() with equivalent call to
get_unused_fd_flags(0) to preserve current behavor for existing code.

The hard coded flag value (0) should be reviewed on a per-subsystem basis,
and, if possible, set to O_CLOEXEC.

Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Link: http://lkml.kernel.org/r/cover.1376327678.git.ydroneaud@opteya.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-08-22 10:20:05 -06:00
Alexey Kardashevskiy 6cdd978213 vfio: add external user support
VFIO is designed to be used via ioctls on file descriptors
returned by VFIO.

However in some situations support for an external user is required.
The first user is KVM on PPC64 (SPAPR TCE protocol) which is going to
use the existing VFIO groups for exclusive access in real/virtual mode
on a host to avoid passing map/unmap requests to the user space which
would made things pretty slow.

The protocol includes:

1. do normal VFIO init operation:
	- opening a new container;
	- attaching group(s) to it;
	- setting an IOMMU driver for a container.
When IOMMU is set for a container, all groups in it are
considered ready to use by an external user.

2. User space passes a group fd to an external user.
The external user calls vfio_group_get_external_user()
to verify that:
	- the group is initialized;
	- IOMMU is set for it.
If both checks passed, vfio_group_get_external_user()
increments the container user counter to prevent
the VFIO group from disposal before KVM exits.

3. The external user calls vfio_external_user_iommu_id()
to know an IOMMU ID. PPC64 KVM uses it to link logical bus
number (LIOBN) with IOMMU ID.

4. When the external KVM finishes, it calls
vfio_group_put_external_user() to release the VFIO group.
This call decrements the container user counter.
Everything gets released.

The "vfio: Limit group opens" patch is also required for the consistency.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-08-05 10:52:36 -06:00
Alex Williamson c64019302b vfio: Ignore sprurious notifies
Remove debugging WARN_ON if we get a spurious notify for a group that
no longer exists.  No reports of anyone hitting this, but it would
likely be a race and not a bug if they did.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-07-24 16:36:40 -06:00
Alex Williamson de9c7602ca vfio: Don't overreact to DEL_DEVICE
BUS_NOTIFY_DEL_DEVICE triggers IOMMU drivers to remove devices from
their iommu group, but there's really nothing we can do about it at
this point.  If the device is in use, then the vfio sub-driver will
block the device_del from completing until it's released.  If the
device is not in use or not owned by a vfio sub-driver, then we
really don't care that it's being removed.

The current code can be triggered just by unloading an sr-iov driver
(ex. igb) while the VFs are attached to vfio-pci because it makes an
incorrect assumption about the ordering of driver remove callbacks
vs the DEL_DEVICE notification.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-07-24 16:36:00 -06:00
Linus Torvalds 15a49b9a90 vfio Updates for v3.11
Largely hugepage support for vfio/type1 iommu and surrounding cleanups and fixes.
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Merge tag 'vfio-v3.11' of git://github.com/awilliam/linux-vfio

Pull vfio updates from Alex Williamson:
 "Largely hugepage support for vfio/type1 iommu and surrounding cleanups
  and fixes"

* tag 'vfio-v3.11' of git://github.com/awilliam/linux-vfio:
  vfio/type1: Fix leak on error path
  vfio: Limit group opens
  vfio/type1: Fix missed frees and zero sized removes
  vfio: fix documentation
  vfio: Provide module option to disable vfio_iommu_type1 hugepage support
  vfio: hugepage support for vfio_iommu_type1
  vfio: Convert type1 iommu to use rbtree
2013-07-10 14:50:08 -07:00
Alex Williamson 6d6768c61b vfio: Limit group opens
vfio_group_fops_open attempts to limit concurrent sessions by
disallowing opens once group->container is set.  This really doesn't
do what we want and allow for inconsistent behavior, for instance a
group can be opened twice, then a container set giving the user two
file descriptors to the group.  But then it won't allow more to be
opened.  There's not much reason to have the group opened multiple
times since most access is through devices or the container, so
complete what the original code intended and only allow a single
instance.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-06-25 16:06:54 -06:00
Alexey Kardashevskiy 5ffd229c02 powerpc/vfio: Implement IOMMU driver for VFIO
VFIO implements platform independent stuff such as
a PCI driver, BAR access (via read/write on a file descriptor
or direct mapping when possible) and IRQ signaling.

The platform dependent part includes IOMMU initialization
and handling.  This implements an IOMMU driver for VFIO
which does mapping/unmapping pages for the guest IO and
provides information about DMA window (required by a POWER
guest).

Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-06-20 16:55:14 +10:00
Alexey Kardashevskiy 9a6aa279d3 vfio: fix crash on rmmod
devtmpfs_delete_node() calls devnode() callback with mode==NULL but
vfio still tries to write there.

The patch fixes this.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-06-05 08:54:16 -06:00
Alex Williamson 664e9386bd vfio: Set container device mode
Minor 0 is the VFIO container device (/dev/vfio/vfio).  On it's own
the container does not provide a user with any privileged access.  It
only supports API version check and extension check ioctls.  Only by
attaching a VFIO group to the container does it gain any access.  Set
the mode of the container to allow access.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-04-30 15:42:28 -06:00
Alex Williamson 0b43c08233 vfio: Use down_reads to protect iommu disconnects
If a group or device is released or a container is unset from a group
it can race against file ops on the container.  Protect these with
down_reads to allow concurrent users.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reported-by: Michael S. Tsirkin <mst@redhat.com>
2013-04-29 08:41:36 -06:00
Alex Williamson 9587f44aa6 vfio: Convert container->group_lock to rwsem
All current users are writers, maintaining current mutual exclusion.
This lets us add read users next.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-04-25 16:12:38 -06:00
Vijay Mohan Pandarathil 44f507163d VFIO: Wrapper for getting reference to vfio_device
- Added vfio_device_get_from_dev() as wrapper to get
  reference to vfio_device from struct device.

- Added vfio_device_data() as a wrapper to get device_data from
  vfio_device.

Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-03-11 09:28:44 -06:00
Tejun Heo a1c36b166b vfio: convert to idr_alloc()
Convert to the much saner new idr interface.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-27 19:10:19 -08:00
Alex Williamson 2b489a45f6 vfio: whitelist pcieport
pcieport does nice things like manage AER and we know it doesn't do
DMA or expose any user accessible devices on the host.  It also keeps
the Memory, I/O, and Busmaster bits enabled, which is pretty handy
when trying to use anyting below it.  Devices owned by pcieport cannot
be given to users via vfio, but we can tolerate them not being owned
by vfio-pci.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-02-14 14:02:13 -07:00
Alex Williamson e014e9444a vfio: Protect vfio_dev_present against device_del
vfio_dev_present is meant to give us a wait_event callback so that we
can block removing a device from vfio until it becomes unused.  The
root of this check depends on being able to get the iommu group from
the device.  Unfortunately if the BUS_NOTIFY_DEL_DEVICE notifier has
fired then the device-group reference is no longer searchable and we
fail the lookup.

We don't need to go to such extents for this though.  We have a
reference to the device, from which we can acquire a reference to the
group.  We can then use the group reference to search for the device
and properly block removal.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-02-14 14:02:13 -07:00
Jiang Liu de2b3eeafb VFIO: use ACCESS_ONCE() to guard access to dev->driver
Comments from dev_driver_string(),
/* dev->driver can change to NULL underneath us because of unbinding,
 * so be careful about accessing it.
 */

So use ACCESS_ONCE() to guard access to dev->driver field.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2012-12-07 13:43:50 -07:00
Jiang Liu 9df7b25ab7 VFIO: unregister IOMMU notifier on error recovery path
On error recovery path in function vfio_create_group(), it should
unregister the IOMMU notifier for the new VFIO group. Otherwise it may
cause invalid memory access later when handling bus notifications.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2012-12-07 13:43:50 -07:00
Al Viro 2903ff019b switch simple cases of fget_light to fdget
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-09-26 22:20:08 -04:00
Al Viro 1d3653a79c switch vfio_group_set_container() to fget_light()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-09-26 21:10:09 -04:00
Al Viro 31605debdf vfio: grab vfio_device reference *before* exposing the sucker via fd_install()
It's not critical (anymore) since another thread closing the file will block
on ->device_lock before it gets to dropping the final reference, but it's
definitely cleaner that way...

Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-08-22 10:26:42 -04:00
Al Viro 90b1253e41 vfio: get rid of vfio_device_put()/vfio_group_get_device* races
we really need to make sure that dropping the last reference happens
under the group->device_lock; otherwise a loop (under device_lock)
might find vfio_device instance that is being freed right now, has
already dropped the last reference and waits on device_lock to exclude
the sucker from the list.

Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-08-22 10:26:13 -04:00
Al Viro 6d2cd3ce81 vfio: get rid of open-coding kref_put_mutex
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-08-22 10:25:19 -04:00
Al Viro 934ad4c235 vfio: don't dereference after kfree...
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-08-22 10:23:04 -04:00
Alex Williamson 73fa0d10d0 vfio: Type1 IOMMU implementation
This VFIO IOMMU backend is designed primarily for AMD-Vi and Intel
VT-d hardware, but is potentially usable by anything supporting
similar mapping functionality.  We arbitrarily call this a Type1
backend for lack of a better name.  This backend has no IOVA
or host memory mapping restrictions for the user and is optimized
for relatively static mappings.  Mapped areas are pinned into system
memory.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2012-07-31 08:16:23 -06:00
Alex Williamson cba3345cc4 vfio: VFIO core
VFIO is a secure user level driver for use with both virtual machines
and user level drivers.  VFIO makes use of IOMMU groups to ensure the
isolation of devices in use, allowing unprivileged user access.  It's
intended that VFIO will replace KVM device assignment and UIO drivers
(in cases where the target platform includes a sufficiently capable
IOMMU).

New in this version of VFIO is support for IOMMU groups managed
through the IOMMU core as well as a rework of the API, removing the
group merge interface.  We now go back to a model more similar to
original VFIO with UIOMMU support where the file descriptor obtained
from /dev/vfio/vfio allows access to the IOMMU, but only after a
group is added, avoiding the previous privilege issues with this type
of model.  IOMMU support is also now fully modular as IOMMUs have
vastly different interface requirements on different platforms.  VFIO
users are able to query and initialize the IOMMU model of their
choice.

Please see the follow-on Documentation commit for further description
and usage example.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2012-07-31 08:16:22 -06:00