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  1. 04 Mar, 2022 4 commits
    • Michael S. Tsirkin's avatar
      virtio_console: break out of buf poll on remove · 0e7174b9
      Michael S. Tsirkin authored 
      A common pattern for device reset is currently:
vdev->config->reset(vdev);
.. cleanup ..

reset prevents new interrupts from arriving and waits for interrupt
handlers to finish.

However if - as is common - the handler queues a work request which is
flushed during the cleanup stage, we have code adding buffers / trying
to get buffers while device is reset. Not good.

This was reproduced by running
	modprobe virtio_console
	modprobe -r virtio_console
in a loop.

Fix this up by calling virtio_break_device + flush before reset.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1786239Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
      0e7174b9
    • Michael S. Tsirkin's avatar
      virtio: document virtio_reset_device · c46eccda
      Michael S. Tsirkin authored 
      Looks like most callers get driver/device removal wrong.
Document what's expected of callers.
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
      c46eccda
    • Michael S. Tsirkin's avatar
      virtio: acknowledge all features before access · 4fa59ede
      Michael S. Tsirkin authored 
      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 404123c2 ("virtio: allow drivers to
validate features") with fallout in at least block and net.  We have a
partial work-around in commit 2f9a174f ("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: default avatarJason Wang <jasowang@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 404123c2 ("virtio: allow drivers to validate features")
Fixes: 2f9a174f ("virtio: write back F_VERSION_1 before validate")
Cc: "Halil Pasic" <pasic@linux.ibm.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
      4fa59ede
    • Michael S. Tsirkin's avatar
      virtio: unexport virtio_finalize_features · 838d6d34
      Michael S. Tsirkin authored 
      virtio_finalize_features is only used internally within virtio.
No reason to export it.
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Acked-by: default avatarJason Wang <jasowang@redhat.com>
      838d6d34
  3. 27 Feb, 2022 4 commits
  5. 26 Feb, 2022 22 commits
  7. 25 Feb, 2022 10 commits
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