Even when volume is not persistent (like TemplateBasedVM:root), it
should be resizeable. Just the new size, similarly to the volume
content, will be reverted after qube shutdown.
Additionally, when VM is running, volume resize should affect _only_ its
temporary snapshot. This way resize can be properly reverted together
with actual volume changes (which include resize2fs call).
FixesQubesOS/qubes-issues#3519
- catch both QubesException and libvirtError - do not kill starting VM
just because an error while connecting _other_ VMs to it
- try to detach network first (and do not abort on error) - if
libvirt/libxl will manage to cleanup stale interface this way, the
attach operation below may succeed.
FixesQubesOS/qubes-issues#3163
1. Make sure VMs are started after dom0 actual memory usage is reported
to qmemman, otherwise dom0 will hold 4GB, even if just a little over 1GB
is needed at that time.
2. Request only vm.memory MB from qmemman, instead of vm.maxmem. While
HVM with PCI devices indeed do not support populate-on-demand, this is
already handled in libvirt XML.
The later may often cause VM startup fail on systems with 8GB of memory,
because maxmem is 4GB there and with dom0 keeping the other 4GB (see
point 1) there is not enough memory to start any sych VM.
FixesQubesOS/qubes-issues#3462
* qubesos/pr/187:
Don't fail create/clone if /var/lib/qubes/TYPE/NAME/ exists
Make 'qvm-volume revert' really use the latest revision
Fix wrong mocks of Volume.revisions
* qubesos/pr/185:
vm: remove doc for non-existing event `monitor-layout-change`
vm: include tag/feature name in event name
events: add support for wildcard event handlers
admin.vm.volume.ListSnapshots returned volume revisions in undefined
order, but 'qvm-volume revert' assumes the list to be in chronological
order. Make that assumption true.
clear_outdated_error_markers crashes if memory stats are not retrieved
yet. In practice it crashes at the very first call during daemon
startup, making the whole qmemman unusable.
This fixes bf4306b815
qmemman: clear "not responding" flags when VM require more memory
QubesOS/qubes-issues#3265
- use capital letters in acronyms in documentation to match upstream
documentation.
- refuse to start a PVH with without kernel set - provide meaningful
error message
* qubesos/pr/180:
vm/qubesvm: default to PVH unless PCI devices are assigned
vm/qubesvm: expose 'start_time' property over Admin API
vm/qubesvm: revert backup_timestamp to '%s' format
doc: link qvm-device man page for qvm-block, qvm-pci, qvm-usb
* qubesos/pr/179:
qmemman: request VMs balloon down with 16MB safety margin
qmemman: clear "not responding" flags when VM require more memory
qmemman: slightly improve logging
qmemman: reformat code, especially comments
Human readable format `str(datetime.datetime)` is a nightmare for Admin
API level communication. Especially setting the property in a format
that it was read was not supported, and handling such format in
untrusted input handling code is a bad idea. Revert to a simple intiger
format.
It looks like Linux balloon driver do not always precisely respect
requested target memory, but perform some rounding. Also, in some cases
(HVM domains), VM do not see all the memory that Xen have assigned to it
- there are some additional Xen pools for internal usage.
Include 16MB safety margin in memory requests to account for those two
things. This will avoid setting "no_response" flag for most of VMs.
QubesOS/qubes-issues#3265
Clear slow_memset_react/no_progress flags when VM request more memory
than it have assigned. If there is some available, it may be given to
such VM, solving the original problem (not reacting to balloon down
request). In any case, qmemman algorithm should not try to take away
memory from under-provisioned VM.
FixesQubesOS/qubes-issues#3265
Add logging more info about each domain state:
- last requested target
- no_progress and slow_memset_react flags
This makes it unnecessary to log separately when those flags are cleared.
Rename events:
- domain-feature-set -> domain-feature-set:feature
- domain-feature-delete -> domain-feature-delete:feature
- domain-tag-add -> domain-tag-add:tag
- domain-tag-delete -> domain-tag-delete:tag
Make it consistent with property-* events. It makes more sense to
include tag/feature name in event name, so handler can watch a single
tag/feature - which is the most common case. Otherwise, most handlers
would begin with `if feature == '...'` anyway, wasting time on most
events.
In cases where multiple features/tags should be handled by a single
handler, it is now possible to register a handler with wildcard, for
example `domain-feature-set:*`.
Support registering handlers for more flexible wildcard events: not only
'*', but also 'something*'. This allows to register handlers for
'property-set:*' and such.
When creating a new VM of type DispVM without specifying any template
(e.g. "qvm-create --class DispVM --label red foo"), use default_dispvm.
Otherwise it would fail saying "Got empty response from qubesd."
Load integration tests from outside of core-admin repository, through
entry points.
Create wrapper for VM object to keep very basic compatibility with tests
written for core2. This means if test use only basic functionality
(vm.start(), vm.run()), the same test will work for both core2 and
core3. This is especially important for app-* repositories, where the
same version serves multiple Qubes branches.
This also hides asyncio usage from tests writer.
See QubesOS/qubes-issues#1800 for details on original feature.
Test base functions of dom0 module (creating VM, setting property) and
configuring system inside of VM (through DispVM). The later is done for
each available template (the process use salt installed in that
template, not copied from dom0).
QubesOS/qubes-issues#3316
When dom0 do not provide the kernel, it should also not set kernel
command line in libvirt config. Otherwise qemu in stubdom fails to start
because it get -append option without -kernel, which is illegal
configuration.
FixesQubesOS/qubes-issues#3339
There may be cases when VM providing the network to other VMs is started
later - for example VM restart. While this is rare case (and currently
broken because of QubesOS/qubes-issues#1426), do not assume it will
always be the case.
Add property for IPv6 address ('ip6'). Build default value similarly to
IPv4 - common prefix + QID or Disp ID (for DispVMs).
This all is disabled unless 'ipv6' feature is enabled. It is inherited
from netvm (not template).
Even when enabled, VM may decide to not use it - or simply not support
it.
QubesOS/qubes-issues#718
Allow using default feature value from netvm, not template. This makes
sense for network-related features like using tor, supporting ipv6 etc.
Similarly to check_with_template, expose it also on Admin API.
Having both default_netvm and default_fw_netvm cause a lot of confusion,
because it isn't clear for the user which one is used when. Additionally
changing provides_network property may also change netvm property, which
may be unintended effect. This as a whole make it hard to:
- cover all netvm-changing actions with policy for Admin API
- cover all netvm-changing events (for example to apply the change to
the running VM, or to check for netvm loops)
As suggested by @qubesuser, kill the default_fw_netvm property and
simplify the logic around it.
Since we're past rc1, implement also migration logic. And add tests for
said migration.
FixesQubesOS/qubes-issues#3247
* qubesos/pr/166:
create "lvm" pool using rootfs thin pool instead of hardcoding qubes_dom0-pool00
change default pool code to be fast
cache PropertyHolder.property_list and use O(1) property name lookups
remove unused netid code
cache isinstance(default, collections.Callable)
don't access netvm if it's None in visible_gateway/netmask
There were many cases were the check was missing:
- changing default_netvm
- resetting netvm to default value
- loading already broken qubes.xml
Since it was possible to create broken qubes.xml using legal calls, do
not reject loading such file, instead break the loop(s) by setting netvm
to None when loop is detected. This will be also useful if still not all
places are covered...
Place the check in default_netvm setter. Skip it during qubes.xml loading
(when events_enabled=False), but still keep it in setter, to _validate_ the
value before any property-* event got fired.
If HVM have PCI device, it can't use PoD, so need 'maxmem' memory to be
started. Request that much from qmemman.
Note that is is somehow independent of enabling or not dynamic memory
management for the VM (`service.meminfo-writer` feature). Even if VM
initially had assigned maxmem memory, it can be later ballooned down.
QubesOS/qubes-issues#3207
* 20171107-storage:
api/admin: add API for changing revisions_to_keep dynamically
storage/file: move revisions_to_keep restrictions to property setter
api/admin: hide dd statistics in admin.vm.volume.Import call
storage/lvm: fix importing different-sized volume from another pool
storage/file: fix preserving spareness on volume clone
api/admin: add pool size and usage to admin.pool.Info response
storage: add size and usage properties to pool object
* 20171107-tests-backup-api-misc:
test: make race condition on xterm close less likely
tests/backupcompatibility: fix handling 'internal' property
backup: fix handling target write error (like no disk space)
tests/backupcompatibility: drop R1 format tests
backup: use offline_mode for backup collection
qubespolicy: fix handling '$adminvm' target with ask action
app: drop reference to libvirt object after undefining it
vm: always log startup fail
api: do not log handled errors sent to a client
tests/backups: convert to new restore handling - using qubesadmin module
app: clarify error message on failed domain remove (used somewhere)
Fix qubes-core.service ordering
currently it takes 100ms+ to determine the default pool every time,
including subprocess spawning (!), which is unacceptable since
finding out the default value of properties should be instantaneous
instead of checking every thin pool to see if the root device is in
it, find and cache the name of the root device thin pool and see if
there is a configured pool with that name
xterm is very fast on closing when application inside terminates. It is
so fast with closing on keydown event that xdotool do not manage to send
keyup event, resulting in xdotool crash. Add a little more time for
that.
When writing process returns an error, prefer reporting that one,
instead of other process (which in most cases will be canceled, so
the error will be meaningless CancelledError).
Then, include sanitized stderr from VM process in the error message.
This object is used solely for manipulating qubes.xml for the backup. Do
not open any connection to hypervisor/QubesDB/libvirt etc. This will
help avoiding various leaks (memory, FD).
Do not try to access that particular object (wrapper) when it got
undefined. If anyone want to access it, appropriate code should do a new
lookup, and probably re-define the object.
Those "errors" are already properly handled, and if necessary logged
independently by appropriate function. In some cases, such logs are
misleading (for example QubesNoSuchPropertyError is a normal thing
happening during qvm-ls).
FixesQubesOS/qubes-issues#3238
Besides converting itself, change how the test verify restore
correctness: first collect VM metadata (and hashes of data) into plain
dict, then compare against it. This allow to destroy old VMs objects
before restoring the backup, so avoid having duplicate objects of the
same VM - which results in weird effects like trying to undefine libvirt
object twice.
Point to system logs for more details. Do not include them directly in
the message for privacy reasons (Admin API client may not be given
permission to it).
QubesOS/qubes-issues#3273QubesOS/qubes-issues#3193
This one pool/volume property makes sense to change dynamically. There
may be more such properties, but lets be on the safe side and take
whitelist approach - allow only selected (just one for now), instead of
blacklisting any harmful ones.
QubesOS/qubes-issues#3256
Do not check for accepted value only in constructor, do that in property
setter. This will allow enforcing the limit regardless of how the value
was set.
This is preparation for dynamic revisions_to_keep change.
QubesOS/qubes-issues#3256
The previous version did not ensure that the stopped/shutdown event was
handled before a new VM start. This can easily lead to problems like in
QubesOS/qubes-issues#3164.
This improved version now ensures that the stopped/shutdown events are
handled before a new VM start.
Additionally this version should be more robust against unreliable
events from libvirt. It handles missing, duplicated and delayed stopped
events.
Instead of one 'domain-shutdown' event there are now 'domain-stopped'
and 'domain-shutdown'. The later is generated after the former. This way
it's easy to run code after the VM is shutdown including the stop of
it's storage.
If domain got removed during the tests (for example DispVM), vm.close()
wouldn't be called in cleanup and some file descriptors will be
leaked. Add event handler for cleaning this up. Do not use close()
method here, because it is destructive, but the object may still be used
by the test.
1. Fire both property-pre-del:netvm and property-del:netvm - those
events should be fired in pairs - especially one may assume the other
will be called too. This is the case here - one disconnect old netvm,
the other connect the new one.
2. Remove spurious 'newvalue' argument for property-del:netvm event.
3. Fix logic for default_fw_netvm/default_netvm usage. The former is
used if vm.provides_network=True.
If there was some netvm set, unset it first (same as with ordinary set).
Otherwise it will try to attach new netvm without detaching the old one
first.
oldvalue should contain the old value, even if it was default one. Same
as in property-(pre-)set events. If event want to check if that is
default value, it is always possible (in pre- event), but in practice
actual value is most useful.
This bug prevented netvm changing events from working when reseting
netvm.
Allow to get default value even it isn't set currently. This will allow
(G)UI to present better view, without duplicating logic for default
value.
FixesQubesOS/qubes-issues#3197
Check resize on each template separately, because it involves VM's
scripts (either qubes.ResizeDisk service, or some startup script).
QubesOS/qubes-issues#3173
- clone all features, not just qrexec (especially include 'gui')
- do not leak VM reference on failed test
- add test for online root volume resize
QubesOS/qubes-issues#3173
- make it clear that failed qubes.ResizeDisk service call means the need
to resize filesystem manually (but not necessarily the volume itself)
- propagate exceptions raised by async storage pool implementations
Related QubesOS/qubes-issues#3173
Expired rules are skipped while loading the firewall. Do that also when
such rules expired after loading the firewall. This applies to both
Admin API and actually applying the rules (sending them to appropriate
VM).
Related QubesOS/qubes-issues#3020
* bug3164:
tests: add regression test for #3164
storage/lvm: make sure volume cache is refreshed after changes
storage/lvm: fix Volume.verify()
storage/lvm: remove old volume only after successfully cloning new one
This is a race condition, so to make it more likely to fail (if it's
broken), make some things manually. In normal circumstances this order
of actions is also possible, just less likely to happen. But as seen in
the bug report, happens from time to time.
QubesOS/qubes-issues#3164
In some cases, it may happen that new volume (`self._vid_snap`) does not
exists. This is normally an error, but even in such a case, do not
remove the only remaining instance of volume (`self.vid`). Instead,
rename it temporarily and remove only after new volume is successfully
cloned.
FixesQubesOS/qubes-issues#3164
This applies to qvm-template-postprocess, which at the beginning try to
resize root volume to appropriate size. It makes more sense to silently
succeed here, instead of forcing every client-side utility to check if
the volume have already desired size.
- Use proper features/services names (updates proxy test).
- Fix logic error in wait_for_window.
- Fix test for qvm-sync-clock (first sync clockvm, then dom0), also fix
cleanup (unset clockvm before removing it)
- More fixes for asyncio usage
* fixes-20170929:
vm: do not start QubesDB watch instance multiple times
vm: report storage.stop() errors to log
vm: move comment
storage: fix method name in LinuxModules volume
Prevent removing domain that is referenced from anywhere
vm: add vm.klass property
Move QubesVM.{name,qid,uuid,label} to BaseVM
vm: do not allow deleting template property from AppVM and DispVM
vm/qubesvm: emit event on failed startup
vm/qubesvm: remove duplicated qmemman_client.close()
vm/dispvm: cleanup DispVM also on failed startup
vm/dispvm: fix error message
ext/block: properly list devtype=cdrom option
block: fix handling non-existing devices
block: improve handling device name and description
vm.create_qdb_entries can be called multiple times - for example when
changing VM IP. Move starting qdb watcher to start(). And just in case,
cleanup old watcher (if still exists) before starting new one.
This fixes one FD leak.
Do not use self.fail when handling exception - this will keep exception
object referenced, which in turn have reference to domain object (via
traceback).
- Prefer instance attributes over local variables - the former ones do
not leak into traceback object and are cleaned up by tests framework.
- Use 'with' syntax for handling files.
- Use subprocess.DEVNULL instead of open('/dev/null') where applicable
- Delete local variables when not needed anymore.
- Fix str/bytes
- Call skipTest as early as possible - before doing any setup
- Fix networking tests - configuration commands needs to be called as
root (missing user= argument).
- Fix setting firewall - policy is no longer changeable
- Add missing loop.run_until_complete() calls.
- Convert subprocess.Popen to asyncio.create_subprocess_exec where
needed (when called process needs to communicate with qubesd).
- Cleanup processes (call .wait()).
There is no more significant difference between PV and HVM. VMs are HVM
by default anyway. More important for this test is difference between
Linux (with Qubes packages installed) and other OS-es. Rename tests
accordingly. The later one is still incomplete.
The most important change is doing vm.close() when removing domain -
this means it wouldn't be cleaned later by iterating over app.domains.
Other changes include removing VMs in the right order, regarding netvm
dependency (otherwise killing or removing may fail). And one more
missing coroutine handling (in shutdown_and_wait).
Catch exception there and log it. Otherwise asyncio complains about not
retrieved exception. There is no one else to handle this exception,
because shutdown event is triggered from libvirt, not any Admin API.
Allow to get domain class as a property, not using admin.vm.List call.
This makes it unnecessary to call admin.vm.List on the client side to
construct wrapper object.
There is intentionally no default template in terms of qubes.property
definition, to not cause problems when switching global default_template
property - like breaking some VMs, or forcing the user to shutdown all
of them for this. But this also means it shouldn't be allowed to reset
template to "default" value, because it will result in a VM without
template at all.
FixesQubesOS/qubes-issues#3115
If VM startup failed before starting anything (even in paused state),
there will be no further event, not even domain-shutdown. This makes it
hard for event-listening applications (like domains tray) to account
domain state. Fix this by emiting domain-start-failed event in every
case of failed startup after emiting domain-pre-start.
Related QubesOS/qubes-issues#3100
* qubesos/pr/150:
qubes/tests: moar fixes
test-packages: add missing libvirt classes
qubes/tests: do not deadlock on .drain()
qubes/vm: put name= first in __repr__
tests: fix some memory leaks
tests: complain about memory leaks
tests: use one event loop and one libvirtaio impl
Recently libvirt removed support for changing event implementation.
Therefore we have to use a single, global one and we check if it is
empty between tests.
On certain locales (e.g. danish) `usage_percent` will output a comma-separated number, which will make `attr` point the last two decimal points, s.t. `return vol_info['attr'][4] == 'a'` (in the `verify` func) will fail and `qubesd` wont run.
* cdrom-boot:
devices: fix error reporting
api/admin: implement admin.vm.device....Set.persistent
devices: implement DeviceCollection.update_persistent()
devices: move DeviceInfo definition earlier
api: do not fail events when listener is cancelled in the meantime
'dispvm_allowed' name was confusing, because it suggested being able to
spawn new DispVMs, not being a template for DispVM.
FixesQubesOS/qubes-issues#3047
Clone properties from DispVM template after setting base properties
(qid, name, uuid). This means we can use standard clone_properties()
function. Otherwise various setters may fail - for example
netvm setter require uuid property initialized (for VM lookup in VM
collection).
Also, make dispvm_allowed check more robust - include direct creation of
DispVM, and also check just before VM startup (if property was changed
in the meantime).
FixesQubesOS/qubes-issues#3057
qvm-sync-clock in dom0 now synchronize only dom0 time. For VM time,
qvm-sync-clock needs to be called in VM. Also, both will communicate
with qubesd, so must be called asynchronously from tests.
Allow attached device to be converted from persistent to non-persistent
and the other way around.
This is to allow starting a VM with some device attached temporarily.
When VM is not running, it is possible to attach device only
persistently, so this change will allow to do that, then, after starting
the VM, change it to non-persistent - so it will not be attached again
at further startups.
QubesOS/qubes-issues#3055
This is because .tearDown() is not executed if the exception occurs in
setUp() [for example self.skipTest() raises an exception]. The lower
levels of .tearDown() being executed are critical to not leaking file
descriptors.
First, cache objects created with init_volume - this is the only place
where we have full volume configuration (including snap_on_start and
save_on_stop properties).
But also implement get_volume method, to get a volume instance for given
volume id. Such volume instance may be incomplete (other attributes are
available only in owning domain configuration), but it will be enough
for basic operations - like cheching and changing its size, cloning
etc.
Listing volumes still use list of physically present volumes.
This makes it possible to start qubesd service, without physical
presence of some storage devices. Starting VMs using such storage would
still fail, of course.
FixesQubesOS/qubes-issues#2960
This is useful to select default DispVM template for VMs started
directly by the user. This makes sense as long as AdminVM == GUIVM.
QubesOS/qubes-issues#2974
Add public Admin API call to create Disposable VM that would be
automatically destroyed after shutdown. Do not keep this functionality
for qrexec-policy tool only.
Also, use admin.vm.Start there, instead of internal.vm.Start and
admin.vm.Kill instead of internal.vm.CleanupDispVM (this is enough,
because DispVM now have auto_cleanup property).
QubesOS/qubes-issues#2974
Add auto_cleanup property, which remove DispVM after its shutdown
- this is to unify DispVM handling - less places needing special
handling after DispVM shutdown.
New DispVM inherit all settings from respective AppVM. Move this from
classmethod `DispVM.from_appvm()`, to DispVM constructor. This unify
creating new DispVM with any other VM class.
Notable exception are attached devices - because only one running VM can
have a device attached, this would prevent second DispVM started from
the same AppVM. If one need DispVM with some device attached, one can
create DispVM with auto_cleanup=False. Such DispVM will still not have
persistent storage (as any other DispVM).
Tests included.
QubesOS/qubes-issues#2974
* services:
tests: check clockvm-related handlers
doc: include list of extensions
qubesvm: fix docstring
ext/services: move exporting 'service.*' features to extensions
app: update handling features/service os ClockVM
* tests-storage:
tests: register libvirt events
tests: even more agressive cleanup in tearDown
app: do not wrap libvirt_conn.close() in auto-reconnect wrapper
api: keep track of established connections
tests: drop VM cleanup from tearDownClass, fix asyncio usage in tearDown
storage: fix Storage.clone and Storage.clone_volume
tests: more tests fixes
firewall: raise ValueError on invalid hostname in dsthost=
qmemman: don't load qubes.xml
tests: fix AdminVM test
tests: create temporary files in /tmp
tests: remove renaming test - it isn't supported anymore
tests: various fixes for storage tests
tests: fix removing LVM volumes
tests: fix asyncio usage in some tests
tests: minor fixes to api/admin tests
storage/file: create -cow.img only when needed
storage: move volume_config['source'] filling to one place
app: do not create 'default' storage pool
app: add missing setters for default_pool* global properties
* qdb-watch:
tests: add qdb_watch test
ext/block: make use of QubesDB watch
vm: add API for watching changes in QubesDB
vm: optimize imports
api/admin: don't send internal events in admin.Events
Add explanation why admin.vm.volume.Import is a custom script
Follow change of qubesdb path return type
Rename vm.qdb to vm.untrusted_qdb
Threis no more ntpd service used - new approach do not conflict with
ntpd. Because of this, new feature is named 'service.clocksync', and
should be _enabled_ in ClockVM ('ntpd' was disabled there).
QubesOS/qubes-issues#1230
When an API call is interrupted, the relevant coroutine is cancelled -
which means it may throw CancelledError. At the same time, cancelled
call have related socket already closed (and transport set to None). But
QubesDaemonProtocol.respond try to close the transport again, which
fails. Fix handling this case.
Get a VM statistics once. If previous measurements are provided,
calculate difference too. This is backend part of upcoming
admin.vm.Stats service.
QubesOS/qubes-issues#853
Remove some more references to objects holding (possibly indirectly)
reference to libvirt connection:
- local variables in tearDown function
- running Admin API calls (especially admin.Events)
- vmm._libvirt_conn directly, in case some reference to Qubes()
is still there
- any instance attribute that is an object from 'qubes' python package
(instead of just those descending from BaseVM)
- do not create new Qubes() instance for removing VMs - if we already
have one in self.app
Then trigger garbage collector to really cleanup those objects (and
close relevant file descriptors). It's important do do this before
closing event loop, because some of descructors may try to use it (for
example remove registered handlers).
When tearDownClass is executed, event loop is already closed. Since no
test really need it right now, drop support for test class-wide VMs and
convert those methods back to instance methods.
Also put coroutines (vm.remove_from_disk, vm.kill) onto event loop.
Only qubesd should load qubes.xml directly. Put a TODO comments for now
in place of slow VM reporting, invent some better mechanism later.
This loading of qubes.xml caused deadlocks, because qmemnan kept open
file descriptor (in locked state).
Since it is no longer child of QubesVM, constructor do not take 'qid'
and 'name' arguments.
Also:
- remove other dropped properties tests (netvm, storage related)
- make the test working in non-dom0
- improve TestPool mock - init_volume now return appropriate mock type,
instead of TestPool
- improve patching base directory (/var/lib/qubes) - it is stored in
more than one place...
- fix inheritance in TC_01_ThinPool class
- fix expected LVM volume names ('vm-' prefix)
- fix cleanup after FilePool tests - remove temporary qubes.xml
- asyncio usage
- better reporting in integ.storage - include error message in the
report, not only as a comment in code
Don't set 'source' volume in various places (each VM class constructor
etc), do it as part of volume initialization. And when it needs to be
re-calculated, call storage.init_volume again.
This code was duplicated, and as usual in such a case, those copies
were different - one have set 'size', the other one not.
QubesOS/qubes-issues#2256
Since we have app.default_pool* properties, create appropriately named
pool and let those properties choose the right pool. This also means we
don't need to specify pool name in default volume config anymore
QubesOS/qubes-issues#2256
Some events are internal for a sole purpose of getting some data from
extension. Since listeners of admin.Events cannot return anything, there
is no sense in sending those events there.
The old format have many issues and is discouraged by tar developers. In
this case the most important one is header with possible non-ASCII
characters, which will result in UnicodeDecodeError (tarfile module
require header parts in utf-8).
PAX format is much cleaner, as it use standard mechanism for extended
headers.
Since we have LVM by default, it is possible to backup VMs while they
are running. For now it will include its state from before startup, but
later we may implement some other logic (a snapshot of running VM).
Do not assume static list of volume (although it is true for now), and
also use proper API for getting volume size, instead of assuming it's a
normal file.
Changed the inheritance hierarchy:
1. Renamed `SystemTestsMixin` to `SystemTestCase`
2. `SystemTestCase` is a child of `QubesTestCase`
3. All classes extending the prior `SystemTestsMixin` now just extend `object`
