There are two pretty similar functions qemuProcessReadLog and
qemuProcessReadChildErrors. Both read from the QEMU log file
and try to strip out libvirt messages. The latter then reports
an error, while the former lets the callers report an error.

Re-write qemuProcessReadLog so that it uses a single read
into a dynamically allocated buffer. Then introduce a new
qemuProcessReportLogError that calls qemuProcessReadLog
and reports an error.

Convert all callers to use qemuProcessReportLogError.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Using qemuProcess{Init,Launch,FinishStartup} allows us to run
pre-migration commands on destination before asking QEMU to wait for
incoming migration data.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

NBD storage migration will not work with offline migration anyway and we
already checked that the user did not ask for it. Thus it doesn't make
sense to keep the code after 'done' label where we jump in case of
offline migration.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Some failure paths in qemuMigrationPrepareAny forgot to kill the just
started QEMU process. This patch fixes this by combining 'stop' and
'endjob' label into a new label 'stopjob'. This name was chosen to avoid
confusion with the most common semantics of 'endjob'. Normally, 'endjob'
is always called at the end of an API to stop the job we entered at the
beginning. In qemuMigrationPrepareAny we only want to stop the job in
failure path; on success we need to carry the job over to the Finish
phase.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Traditionally, we pass incoming migration URI on QEMU command line,
which has some drawbacks. Depending on the URI QEMU may initialize its
migration state immediately without giving us a chance to set any
additional migration parameters (this applies mainly for fd: URIs). For
some URIs the monitor may be completely blocked from the beginning until
migration is finished, which means we may be stuck in qmp_capabilities
command without being able to send any QMP commands.

QEMU solved this by introducing "defer" parameter for -incoming command
line option. This will tell QEMU to prepare for an incoming migration
while the actual incoming URI is sent using migrate-incoming QMP
command. Before calling this command we can normally talk to the
monitor and even set any migration parameters which will be honored by
the incoming migration.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Move the code from qemuMigrationFinish into a dedicated function.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Since we require QEMU 0.12.0, we can assume that QEMU supports
all of the fd, tcp, unix and exec migration protocols.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

The code reported that a migration flag is unsupported but didn't jump
to the error label. Probably an oversight in commit f88af9dc that
introduced the flag checking.

Since the flag was not enabled when 'eating' the migration cookie,
libvirt reported a bogus error when memory hotplug was enabled:

 unsupported migration cookie feature memory-hotplug

The error was ignored though due to a bug in the code so it slipped
through testing.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1278404

In commit f41be296, we moved vm->persistent check into
qemuDomainRemoveInactive, but we didn't change the vm->persistent
before call qemuDomainRemoveInactive in some place before and just
call it to remove the inactive vm.
Signed-off-by: NLuyao Huang <lhuang@redhat.com>

Tunnelled migration can hang if the destination qemu exits despite all the
ABI checks. This happens whenever the destination qemu exits before the
complete transfer is noticed by source qemu. The savevm state checks at
runtime can fail at destination and cause qemu to error out.
The source qemu cant notice it as the EPIPE is not propogated to it.
The qemuMigrationIOFunc() notices the stream being broken from virStreamSend()
and it cleans up the stream alone. The qemuMigrationWaitForCompletion() would
never get to 100% transfer completion.
The qemuMigrationWaitForCompletion() never breaks out as well since
the ssh connection to destination is healthy, and the source qemu also thinks
the migration is ongoing as the Fd to which it transfers, is never
closed or broken. So, the migration will hang forever. Even Ctrl-C on the
virsh migrate wouldn't be honoured. Close the source side FD when there is
an error in the stream. That way, the source qemu updates itself and
qemuMigrationWaitForCompletion() notices the failure.

Close the FD for all kinds of errors to be sure. The error message is not
copied for EPIPE so that the destination error is copied instead later.

Note:
Reproducible with repeated migrations between Power hosts running in different
subcores-per-core modes.
Signed-off-by: NShivaprasad G Bhat <sbhat@linux.vnet.ibm.com>

qemuMigrationIsAllowed would disallow offline migration if the VM
contained host devices or memory modules. Since during offline migration
we don't transfer any state we can safely migrate VMs with such
configuration.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1265049

Use the migration @flags for checking various migration aspects rather
than picking them out as booleans. Document the new semantics in the
function header.

Now that qemuMigrationIsAllowed is always called with @vm, we can drop
the @def argument and simplify the control flow.

Additionally the comment is invalid so drop it.

Extract the hostdev check from qemuMigrationIsAllowed into a separate
function since that is the only part that needs to be done in the v2
migration protocol prepare phase on the destination. All other checks
were added when the v3 protocol existed so they don't need to be
extracted.

This change will allow to drop the @def argument for
qemuMigrationIsAllowed and further simplify the function.

Even though QEMU on the source host reports completed migration and thus
we move to the Finish phase, QEMU on the destination host may still be
processing migration data. Thus before we can start guest CPUs on the
destination, we have to wait for a completed migration event.

https://bugzilla.redhat.com/show_bug.cgi?id=1265902Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

With new QEMU which supports migration events,
qemuMigrationCheckJobStatus needs to explicitly query QEMU for migration
statistics once migration is completed to make sure the caller sees
up-to-date statistics with both old and new QEMU. However, some callers
are not interested in the statistics at all and once we start waiting
for a completed migration on the destination host too, checking the
statistics would even fail. Let's push the decision whether to update
the statistics or not to the caller.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

The function already has two bool parameters and we will need to add a
new one. Let's switch to flags to make the callers readable.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

The destination host gets detailed statistics about the current
migration form the source host via migration cookie and copies them to
the domain object so that they can be queried using
virDomainGetJobStats. However, we should only copy statistics to the
domain object when migration finished successfully.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Even if we are migrating a domain with VIR_MIGRATE_PAUSED flag set, we
should still update the total time of the migration. Updating downtime
doesn't hurt either, even though we don't actually start guest CPUs.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

So far we have the following pattern occurring over and over
again:

  if (!vm->persistent)
      qemuDomainRemoveInactive(driver, vm);

It's safe to put the check into the function and save some LoC.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

Add a new parser flag that will mark code paths that parse XML files
wich will not be used with existing VM state so that post parse
callbacks can possibly do ABI incompatible changes if needed.

Add a simple helper so that the code doesn't have to rewrite the same
condition multiple times.

When persistently migrating a domain to a destination host where the
same domain already exists (i.e., it is persistent and shutdown at the
destination), we would happily throw away the original persistent
definition without properly freeing it. And when updating the definition
fails for some reason we don't properly revert to the original state
leaving the domain broken.

In addition to fixing these issues, the patch also makes sure the domain
definition parsed from a migration cookie is either used or freed.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

For quite a long time we don't need to postpone queueing events until
the end of the function since we no longer have the big driver lock.
Let's make the code of qemuMigrationFinish simpler by queuing events at
the time we generate them.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Every single call to qemuDomainEventQueue() uses the following pattern:

    if (event)
        qemuDomainEventQueue(driver, event);

Let's move the check for valid event to qemuDomainEventQueue and
simplify all callers.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Finish is the final state in v2 of our migration protocol. If something
fails, we have no option to abort the migration and resume the original
domain. Non fatal errors (such as failure to start guest CPUs or make
the domain persistent) has to be treated as success. Keeping the domain
running while reporting the failure was just asking for trouble.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Whenever something fails during incoming migration in Finish phase
before we started guest CPUs, we need to kill the domain in addition to
reporting the failure.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

When we save status XML at the point during migration where we have
already started the domain on destination, we can't really go back and
abort migration. Thus the only thing we can do is to log a warning and
report success.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Offline migration is quite special because we don't really need to do
anything but make the domain persistent. Let's do it separately from
normal migration to avoid cluttering the code with
!(flags & VIR_MIGRATE_OFFLINE).
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Separate code which makes incoming domain persistent into
qemuMigrationPersist.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

If the current live definition does not have memory hotplug enabled, but
the persistent one does libvirt would reject migration if the
destination does not support memory hotplug even if the user didn't want
to persist the VM at the destination and thus the XML containing the
memory hotplug definition would not be used. To fix this corner case the
code will check for memory hotplug in the newDef only if
VIR_MIGRATE_PERSIST_DEST was used.

Commit id '2e7cea24' added a check for an error from Finish instead
of 'unexpected error'; however, if for some reason there wasn't an
error, then virGetLastError could return NULL resulting in the
NULL pointer deref to err->domain.

Libvirt doesn't reliably know the location of the backing chain when
pre-creating images for non-shared migration. This isn't a problem for
full copy, but incremental copy requires the information.

Forbid pre-creating the image in cases where incremental migration is
required. This limitation can perhaps be lifted once libvirt will fully
support loading of backing chain information from the XML.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1249587

When stopping a domain on the destination host after a failed migration,
we need to avoid reseting security labels since the domain is still
running on the source host. While we were correctly doing so in some
cases, there were still some paths which did this wrong.

https://bugzilla.redhat.com/show_bug.cgi?id=1242904Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

If destination libvirt doesn't support memory hotplug since all the
support was introduced by adding new elements the destination would
attempt to start qemu with an invalid configuration. The worse part is
that qemu might hang in such situation.

Fix this by sending a required migration feature called 'memory-hotplug'
to the destination. If the destination doesn't recognize it it will fail
the migration.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1248350

If we are migrating to an UNIX socket, we accept() a connection
from qemu and use that FD to set up a tunnel. However, the FD is
not closed as often as it should be.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

When QEMU exits on destination during migration, the source reports
either success (if the failure happened at the very end) or unhelpful
"unexpectedly failed" error message. However, the Finish API called on
the destination may report a real error so let's use it instead of the
generic one.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>