linux-stable.git/drivers/virtio/virtio.c, branch linux-5.14.y

virtio: write back F_VERSION_1 before validate

2021-10-20T09:57:50+00:00

commit 2f9a174f918e29608564c7a4e8329893ab604fb4 upstream.

The virtio specification virtio-v1.1-cs01 states: "Transitional devices
MUST detect Legacy drivers by detecting that VIRTIO_F_VERSION_1 has not
been acknowledged by the driver."  This is exactly what QEMU as of 6.1
has done relying solely on VIRTIO_F_VERSION_1 for detecting that.

However, the specification also says: "... the driver MAY read (but MUST
NOT write) the device-specific configuration fields to check that it can
support the device ..." before setting FEATURES_OK.

In that case, any transitional device relying solely on
VIRTIO_F_VERSION_1 for detecting legacy drivers will return data in
legacy format.  In particular, this implies that it is in big endian
format for big endian guests. This naturally confuses the driver which
expects little endian in the modern mode.

It is probably a good idea to amend the spec to clarify that
VIRTIO_F_VERSION_1 can only be relied on after the feature negotiation
is complete. Before validate callback existed, config space was only
read after FEATURES_OK. However, we already have two regressions, so
let's address this here as well.

The regressions affect the VIRTIO_NET_F_MTU feature of virtio-net and
the VIRTIO_BLK_F_BLK_SIZE feature of virtio-blk for BE guests when
virtio 1.0 is used on both sides. The latter renders virtio-blk unusable
with DASD backing, because things simply don't work with the default.
See Fixes tags for relevant commits.

For QEMU, we can work around the issue by writing out the feature bits
with VIRTIO_F_VERSION_1 bit set.  We (ab)use the finalize_features
config op for this. This isn't enough to address all vhost devices since
these do not get the features until FEATURES_OK, however it looks like
the affected devices actually never handled the endianness for legacy
mode correctly, so at least that's not a regression.

No devices except virtio net and virtio blk seem to be affected.

Long term the right thing to do is to fix the hypervisors.

Cc:  #v4.11
Signed-off-by: Halil Pasic 
Fixes: 82e89ea077b9 ("virtio-blk: Add validation for block size in config space")
Fixes: fe36cbe0671e ("virtio_net: clear MTU when out of range")
Reported-by: markver@us.ibm.com
Reviewed-by: Cornelia Huck 
Link: https://lore.kernel.org/r/20211011053921.1198936-1-pasic@linux.ibm.com
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Greg Kroah-Hartman

virtio: Protect vqs list access

2021-08-10T15:50:55+00:00

VQs may be accessed to mark the device broken while they are
created/destroyed. Hence protect the access to the vqs list.

Fixes: e2dcdfe95c0b ("virtio: virtio_break_device() to mark all virtqueues broken.")
Signed-off-by: Parav Pandit 
Link: https://lore.kernel.org/r/20210721142648.1525924-4-parav@nvidia.com
Signed-off-by: Michael S. Tsirkin

virtio: remove export for virtio_config_{enable, disable}

2021-03-14T08:37:35+00:00

virtio_config_enable(), virtio_config_disable() are only used inside
drivers/virtio/virtio.c, so it doesn't need export the symbols.

Signed-off-by: Xianting Tian 
Link: https://lore.kernel.org/r/1613838498-8791-1-git-send-email-xianting_tian@126.com
Signed-off-by: Michael S. Tsirkin 
Acked-by: Jason Wang 
Reviewed-by: Stefano Garzarella

Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

2020-10-23T18:00:57+00:00

Pull virtio updates from Michael Tsirkin:
 "vhost, vdpa, and virtio cleanups and fixes

  A very quiet cycle, no new features"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  MAINTAINERS: add URL for virtio-mem
  vhost_vdpa: remove unnecessary spin_lock in vhost_vring_call
  vringh: fix __vringh_iov() when riov and wiov are different
  vdpa/mlx5: Setup driver only if VIRTIO_CONFIG_S_DRIVER_OK
  s390: virtio: PV needs VIRTIO I/O device protection
  virtio: let arch advertise guest's memory access restrictions
  vhost_vdpa: Fix duplicate included kernel.h
  vhost: reduce stack usage in log_used
  virtio-mem: Constify mem_id_table
  virtio_input: Constify id_table
  virtio-balloon: Constify id_table
  vdpa/mlx5: Fix failure to bring link up
  vdpa/mlx5: Make use of a specific 16 bit endianness API

virtio: let arch advertise guest's memory access restrictions

2020-10-21T14:34:12+00:00

An architecture may restrict host access to guest memory,
e.g. IBM s390 Secure Execution or AMD SEV.

Provide a new Kconfig entry the architecture can select,
CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS, when it provides
the arch_has_restricted_virtio_memory_access callback to advertise
to VIRTIO common code when the architecture restricts memory access
from the host.

The common code can then fail the probe for any device where
VIRTIO_F_ACCESS_PLATFORM is required, but not set.

Signed-off-by: Pierre Morel 
Reviewed-by: Cornelia Huck 
Reviewed-by: Halil Pasic 
Link: https://lore.kernel.org/r/1599728030-17085-2-git-send-email-pmorel@linux.ibm.com
Signed-off-by: Michael S. Tsirkin 
Acked-by: Christian Borntraeger

virtio: add dma-buf support for exported objects

2020-08-18T08:01:44+00:00

This change adds a new flavor of dma-bufs that can be used by virtio
drivers to share exported objects. A virtio dma-buf can be queried by
virtio drivers to obtain the UUID which identifies the underlying
exported object.

Signed-off-by: David Stevens 
Acked-by: Michael S. Tsirkin 
Link: http://patchwork.freedesktop.org/patch/msgid/20200818071343.3461203-2-stevensd@chromium.org
Signed-off-by: Gerd Hoffmann

treewide: Add SPDX license identifier for more missed files

2019-05-21T08:50:45+00:00

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have MODULE_LICENCE("GPL*") inside which was used in the initial
   scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

virtio: hint if callbacks surprisingly might sleep

2019-03-06T16:19:57+00:00

A virtio transport is free to implement some of the callbacks in
virtio_config_ops in a matter that they cannot be called from
atomic context (e.g. virtio-ccw, which maps a lot of the callbacks
to channel I/O, which is an inherently asynchronous mechanism).
This can be very surprising for developers using the much more
common virtio-pci transport, just to find out that things break
when used on s390.

The documentation for virtio_config_ops now contains a comment
explaining this, but it makes sense to add a might_sleep() annotation
to various wrapper functions in the virtio core to avoid surprises
later.

Note that annotations are NOT added to two classes of calls:
- direct calls from device drivers (all current callers should be
  fine, however)
- calls which clearly won't be made from atomic context (such as
  those ultimately coming in via the driver core)

Signed-off-by: Cornelia Huck 
Signed-off-by: Michael S. Tsirkin

virtio: split device_register into device_initialize and device_add

2018-02-01T14:26:45+00:00

In order to make caller do a simple cleanup, we split device_register
into device_initialize and device_add. device_initialize always succeeds,
so the caller can always use put_device when register_virtio_device faild.

Signed-off-by: weiping zhang 
Suggested-by: Cornelia Huck 
Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Cornelia Huck

virtio: release virtio index when fail to device_register

2017-12-01T14:55:32+00:00

index can be reused by other virtio device.

Cc: stable@vger.kernel.org
Signed-off-by: weiping zhang 
Reviewed-by: Cornelia Huck 
Signed-off-by: Michael S. Tsirkin