Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
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Peter Krempa 81e770c2f1 qemu: blockjob: Transition into 'ready' state only from expected states
In certain rare occasions qemu can transition a block job which was
already 'ready' into 'standby' and then back. If this happens in the
following order libvirt will get confused about the actual job state:

1) the block copy job is 'ready' (job->state == QEMU_BLOCKJOB_STATE_READY)

2) user calls qemuDomainBlockJobAbort with VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT
   flag but without VIR_DOMAIN_BLOCK_JOB_ABORT_ASYNC

3) the block job is switched to synchronous event handling

4) the block job blips to 'standby' and back to 'ready', the event is
   not processed since the blockjob is in sync mode for now

5) qemuDomainBlockJobPivot is called:
    5.1) 'job-complete' QMP command is issued
    5.2) job->state is set to QEMU_BLOCKJOB_STATE_PIVOTING

6) code for synchronous-wait for the job completion in qemuDomainBlockJobAbort
   is invoked

7) the waiting loop calls qemuBlockJobUpdate:

    7.1) job->newstate is QEMU_BLOCKJOB_STATE_READY due to 4)
    7.2) qemuBlockJobEventProcess is called
    7.3) the handler for QEMU_BLOCKJOB_STATE_READY overwrites
         job->state from QEMU_BLOCKJOB_STATE_PIVOTING to QEMU_BLOCKJOB_STATE_READY

8) qemuDomainBlockJobAbort is looking for a finished job, so waits again

9) qemu finishes the blockjob and transitions it into 'concluded' state

10) qemuBlockJobUpdate is triggered again, this time finalizing the job.
    10.1) job->newstate is = QEMU_BLOCKJOB_STATE_CONCLUDED
          job->state is = QEMU_BLOCKJOB_STATE_READY
    10.2) qemuBlockJobEventProcessConcluded is called, the function
          checks whether there was an error with the blockjob. Since
          there was no error job->newstate becomes
          QEMU_BLOCKJOB_STATE_COMPLETED.
    10.3) qemuBlockJobEventProcessConcludedTransition selects the action
          for the appropriate block job type where we have:

    case QEMU_BLOCKJOB_TYPE_COPY:
        if (job->state == QEMU_BLOCKJOB_STATE_PIVOTING && success)
            qemuBlockJobProcessEventConcludedCopyPivot(driver, vm, job, asyncJob);
        else
            qemuBlockJobProcessEventConcludedCopyAbort(driver, vm, job, asyncJob);
        break;

          Since job->state is QEMU_BLOCKJOB_STATE_READY,
          qemuBlockJobProcessEventConcludedCopyAbort is called.

This patch forbids transitions to QEMU_BLOCKJOB_STATE_READY if the
previous job state isn't QEMU_BLOCKJOB_STATE_RUNNING or
QEMU_BLOCKJOB_STATE_NEW.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1951507
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
2021-04-21 14:54:56 +02:00
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po Translated using Weblate (Swedish) 2021-04-19 12:49:32 +02:00
scripts lib: Drop internal virXXXPtr typedefs 2021-04-13 17:00:38 +02:00
src qemu: blockjob: Transition into 'ready' state only from expected states 2021-04-21 14:54:56 +02:00
tests bhyvexml2argvtest: use virCommandToStringFull to strip command path 2021-04-21 14:20:03 +02:00
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libvirt-admin.pc.in Add libvirt-admin library 2015-06-16 13:46:20 +02:00
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Libvirt API for virtualization

Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.

For some of these hypervisors, it provides a stateful management daemon which runs on the virtualization host allowing access to the API both by non-privileged local users and remote users.

Layered packages provide bindings of the libvirt C API into other languages including Python, Perl, PHP, Go, Java, OCaml, as well as mappings into object systems such as GObject, CIM and SNMP.

Further information about the libvirt project can be found on the website:

https://libvirt.org

License

The libvirt C API is distributed under the terms of GNU Lesser General Public License, version 2.1 (or later). Some parts of the code that are not part of the C library may have the more restrictive GNU General Public License, version 2.0 (or later). See the files COPYING.LESSER and COPYING for full license terms & conditions.

Installation

Instructions on building and installing libvirt can be found on the website:

https://libvirt.org/compiling.html

Contributing

The libvirt project welcomes contributions in many ways. For most components the best way to contribute is to send patches to the primary development mailing list. Further guidance on this can be found on the website:

https://libvirt.org/contribute.html

Contact

The libvirt project has two primary mailing lists:

Further details on contacting the project are available on the website:

https://libvirt.org/contact.html