Public bug reported:
Description: kernel: unable to read partitions on virtio-block dasd (kvm)
Symptom: unable to read partitions on virtio-block dasd (kvm)
Problem: verify is called before virtio_finalize_features() , so a
transitional s390 virtio device still serves native endian
(i.e. big endian) config space, while the driver knows that it
is going to accept VERSION_1, so when reading the config space,
it assumes it got little endian, and byteswaps.
Solution: 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.
** Affects: linux (Ubuntu)
Importance: Undecided
Assignee: Skipper Bug Screeners (skipper-screen-team)
Status: New
** Tags: architecture-s39064 bugnameltc-195009 severity-high
targetmilestone-inin---
** Tags added: architecture-s39064 bugnameltc-195009 severity-high
targetmilestone-inin---
** Changed in: ubuntu
Assignee: (unassigned) => Skipper Bug Screeners (skipper-screen-team)
** Package changed: ubuntu => linux (Ubuntu)
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https://bugs.launchpad.net/bugs/1950144
Title:
[UBUNTU 20.04] kernel: unable to read partitions on virtio-block dasd
(kvm)
Status in linux package in Ubuntu:
New
Bug description:
Description: kernel: unable to read partitions on virtio-block dasd (kvm)
Symptom: unable to read partitions on virtio-block dasd (kvm)
Problem: verify is called before virtio_finalize_features() , so a
transitional s390 virtio device still serves native endian
(i.e. big endian) config space, while the driver knows that it
is going to accept VERSION_1, so when reading the config space,
it assumes it got little endian, and byteswaps.
Solution: 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.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1950144/+subscriptions
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