linux-stable.git/drivers/virtio/virtio.c, branch linux-4.19.y

virtio: reenable config if freezing device failed

2024-04-13T10:50:16+00:00

commit 310227f42882c52356b523e2f4e11690eebcd2ab upstream.

Currently, we don't reenable the config if freezing the device failed.

For example, virtio-mem currently doesn't support suspend+resume, and
trying to freeze the device will always fail. Afterwards, the device
will no longer respond to resize requests, because it won't get notified
about config changes.

Let's fix this by re-enabling the config if freezing fails.

Fixes: 22b7050a024d ("virtio: defer config changed notifications")
Cc: 
Cc: "Michael S. Tsirkin" 
Cc: Jason Wang 
Cc: Xuan Zhuo 
Signed-off-by: David Hildenbrand 
Message-Id: <20240213135425.795001-1-david@redhat.com>
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Greg Kroah-Hartman

virtio: acknowledge all features before access

2022-03-16T12:20:27+00:00

commit 4fa59ede95195f267101a1b8916992cf3f245cdb upstream.

The feature negotiation was designed in a way that
makes it possible for devices to know which config
fields will be accessed by drivers.

This is broken since commit 404123c2db79 ("virtio: allow drivers to
validate features") with fallout in at least block and net.  We have a
partial work-around in commit 2f9a174f918e ("virtio: write back
F_VERSION_1 before validate") which at least lets devices find out which
format should config space have, but this is a partial fix: guests
should not access config space without acknowledging features since
otherwise we'll never be able to change the config space format.

To fix, split finalize_features from virtio_finalize_features and
call finalize_features with all feature bits before validation,
and then - if validation changed any bits - once again after.

Since virtio_finalize_features no longer writes out features
rename it to virtio_features_ok - since that is what it does:
checks that features are ok with the device.

As a side effect, this also reduces the amount of hypervisor accesses -
we now only acknowledge features once unless we are clearing any
features when validating (which is uncommon).

IRC I think that this was more or less always the intent in the spec but
unfortunately the way the spec is worded does not say this explicitly, I
plan to address this at the spec level, too.

Acked-by: Jason Wang 
Cc: stable@vger.kernel.org
Fixes: 404123c2db79 ("virtio: allow drivers to validate features")
Fixes: 2f9a174f918e ("virtio: write back F_VERSION_1 before validate")
Cc: "Halil Pasic" 
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Greg Kroah-Hartman

virtio: unexport virtio_finalize_features

2022-03-16T12:20:27+00:00

commit 838d6d3461db0fdbf33fc5f8a69c27b50b4a46da upstream.

virtio_finalize_features is only used internally within virtio.
No reason to export it.

Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Cornelia Huck 
Acked-by: Jason Wang 
Signed-off-by: Greg Kroah-Hartman

virtio: write back F_VERSION_1 before validate

2021-10-20T09:23:02+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: 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

virtio: allow drivers to validate features

2017-04-07T13:38:59+00:00

Some drivers can't support all features in all configurations.  At the
moment we blindly set FEATURES_OK and later FAILED.  Support this better
by adding a callback drivers can use to do some early checks.

Signed-off-by: Michael S. Tsirkin

virtio_net: refactor freeze/restore logic into virtnet reset logic

2017-02-07T15:05:12+00:00

For XDP we will need to reset the queues to allow for buffer headroom
to be configured. In order to do this we need to essentially run the
freeze()/restore() code path. Unfortunately the locking requirements
between the freeze/restore and reset paths are different however so
we can not simply reuse the code.

This patch refactors the code path and adds a reset helper routine.

Signed-off-by: John Fastabend 
Acked-by: Jason Wang 
Signed-off-by: David S. Miller

virtio: fix memory leak of virtio ida cache layers

2015-12-07T15:28:01+00:00

The virtio core uses a static ida named virtio_index_ida for
assigning index numbers to virtio devices during registration.
The ida core may allocate some internal idr cache layers and
an ida bitmap upon any ida allocation, and all these layers are
truely freed only upon the ida destruction. The virtio_index_ida
is not destroyed at present, leading to a memory leak when using
the virtio core as a module and atleast one virtio device is
registered and unregistered.

Fix this by invoking ida_destroy() in the virtio core module
exit.

Cc: stable@vger.kernel.org
Signed-off-by: Suman Anna 
Signed-off-by: Michael S. Tsirkin

virtio: drop virtio_device_is_legacy_only

2015-04-15T03:11:14+00:00

virtio_device_is_legacy_only is now unused, drop
it from core.

Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Cornelia Huck 
Signed-off-by: Rusty Russell