Since (for LVM at least) path is dynamic now, add information about it
to volume info. This is not very useful outside of dom0, but in dom0 it
can be very useful for various scripts.
This will disclose current volume revision id, but it is already
possible to deduce it from snapshots list.
Do not write directly to main volume, instead create temporary volume
and only commit it to the main one when operation is finished. This
solve multiple problems:
- import operation can be aborted, without data loss
- importing new data over existing volume will not leave traces of
previous content - especially when importing smaller volume to bigger
one
- import operation can be reverted - it create separate revision,
similar to start/stop
- easier to prevent qube from starting during import operation
- template still can be used when importing new version
QubesOS/qubes-issues#2256
First rename volume to backup revision, regardless of revisions_to_keep,
then rename -snap to current volume. And only then remove backup
revision (if exceed revisions_to_keep). This way even if commit
operation is interrupted, there is still a volume with the data.
This requires also adjusting few functions to actually fallback to most
recent backup revision if the current volume isn't found - create
_vid_current property for this purpose.
Also, use -snap volume for clone operation and commit it normally later.
This makes it safer to interrupt or even revert.
QubesOS/qubes-issues#2256
Fire 'domain-start-failed' even even if failure occurred during
'domain-pre-start' event. This will make sure if _anyone_ have seen
'domain-pre-start' event, will also see 'domain-start-failed'. In some
cases it will look like spurious 'domain-start-failed', but it is safer
option than the alternative.
Fail the VM start early if some persistently-assigned device is missing.
This will both save time and provide clearer error message.
FixesQubesOS/qubes-issues#3810
is_outdated() may be not supported by given volume pool driver. In that
case skip is_outdated information, instead of crashing the call.
FixesQubesOS/qubes-issues#3767
Before waiting for remaining tasks on event loop (including libvirt
events), make sure all destroyed objects are really destroyed. This is
especially important for libvirt connections, which gets cleaned up only
when appropriate destructor (__del__) register a cleanup callback and it
gets called by the loop.
Use VM's actual IP address as a gateway for other VMs, instead of
hardcoded link-local address. This is important for sys-net generated
ICMP diagnostics packets - those must _not_ have link-local source
address, otherwise wouldn't be properly forwarded back to the right VM.
If domain die when trying to kill it, qubesd may loose a race and try to
kill it anyway. Handle libvirt exception in that case and conver it to
QubesVMNotStartedError - as it would be if qubesd would win the race.
FixesQubesOS/qubes-issues#3755
Scripts do parse its output sometimes (especially `lvs`), so make sure
we always gets the same format, regardless of the environment. Including
decimal separator.
FixesQubesOS/qubes-issues#3753
Don't rely on timestamps to sort revisions - the clock can go backwards
due to time sync. Instead, use a monotonically increasing natural number
as the revision ID.
Old revision example: private.img@2018-01-02-03T04:05:06Z (ignored now)
New revision example: private.img.123@2018-01-02-03T04:05:06Z
* devel-storage-fixes:
storage/file: use proper exception instead of assert
storage/file: import data into temporary volume
storage/lvm: check for LVM LV existence and type when creating ThinPool
storage/lvm: fix size reporting just after creating LV
Similar to LVM changes, this fixes/improves multiple things:
- no old data visible in the volume
- failed import do not leave broken volume
- parially imported data not visible to running VM
QubesOS/qubes-issues#3169
* storage-properties:
storage: use None for size/usage properties if unknown
tests: call search_pool_containing_dir with various dirs and pools
storage: make DirectoryThinPool helper less verbose, add sudo
api/admin: add 'included_in' to admin.pool.Info call
storage: add Pool.included_in() method for checking nested pools
storage: move and generalize RootThinPool helper class
storage/kernels: refuse changes to 'rw' and 'revisions_to_keep'
api/admin: implement admin.vm.volume.Set.rw method
api/admin: include 'revisions_to_keep' and 'is_outdated' in volume info
It may happen that one pool is inside a volume of other pool. This is
the case for example for varlibqubes pool (file driver,
dir_path=/var/lib/qubes) and default lvm pool (lvm_thin driver). The
latter include whole root filesystem, so /var/lib/qubes too.
This is relevant for proper disk space calculation - to not count some
space twice.
QubesOS/qubes-issues#3240QubesOS/qubes-issues#3241
This pool driver support only rw=False and revisions_to_keep=0 volumes.
Since there is API for changing those properties dynamically, block it
at pool driver level, instead of silently ignoring them.
* qubesos/pr/200:
Removed self.rules != old_rules
Avoid UTC datetime
Wrong init var to bool and missing call to total_seconds()
FixesQubesOS/qubes-issues#3661
* qubesos/pr/201:
storage/reflink: reorder start() to be more readable
storage/reflink: simplify
storage/reflink: let _remove_empty_dir() ignore ENOTEMPTY
storage/reflink: show size in refused volume shrink message
storage/reflink: fsync() after resizing existing file
Since Volume.is_outdated() is a method, not a property, add a function
for handling serialization. And at the same time, fix None serialization
(applicable to 'source' property).
QubesOS/qubes-issues#3256
After lot of testing it does not work properly. Could do something more
sophisticated but since calling save() is safe and probably lightweigth it is
not worth probably.
Some handlers may want to call into other VMs (or even the one asking),
but vm.run() functions are coroutines, so needs to be called from
another coroutine. Allow for that.
Also fix typo in documentation.
Some kernels (like pvgrub2) may not provide modules.img and it isn't an
error. Don't break VM startup in that case, skip that device instead.
FixesQubesOS/qubes-issues#3563
"Cannot execute qrexec-daemon!" error is very misleading for a startup
timeout error, make it clearer. This rely on qrexec-daemon using
distinct exit code for timeout error, but even without that, include its
stderr in the error message.
* qubesos/pr/198:
backup.py: add vmN/empty file if no other files to backup
Allow include=None to be passed to admin.backup.Info
Add include_in_backups property for AdminVM
Use !auto_cleanup as DispVM include_in_backups default
Lots of code expects the VM to be Halted after receiving one of these
events, but it could also be Dying or Crashed. Get rid of the Dying case
at least, by waiting until the VM has transitioned out of it.
Fixes e.g. the following DispVM cleanup bug:
$ qvm-create -C DispVM --prop auto_cleanup=True -l red dispvm
$ qvm-start dispvm
$ qvm-shutdown --wait dispvm # this won't remove dispvm
$ qvm-start dispvm
$ qvm-kill dispvm # but this will
* qubesos/pr/194:
reflink: style fix
storage: typo fix
lvm_thin: _remove_revisions() on revisions_to_keep==0
lvm_thin: don't purge one revision too few
lvm_thin: really remove revision
lvm_thin: fill in volume's revisions_to_keep from pool
Using '$' is easy to misuse in shell scripts, shell commands etc. After
all this years, lets abandon this dangerous character and move to
something safer: '@'. The choice was made after reviewing specifications
of various shells on different operating systems and this is the
character that have no special meaning in none of them.
To preserve compatibility, automatically translate '$' to '@' when
loading policy files.
If revisions_to_keep is 0, it may nevertheless have been > 0 before, so
it makes sense to call _remove_revisions() and hold back none (not all)
of the revisions in this case.
* qubesos/pr/190:
Missed one test, adding default-user in assert for test test_621_qdb_vm_with_network in TC_90
replaced underscore by dash and update test accordingly
Updated assert content for test_620_qdb_standalone in TC_90_QubesVM
Added the default_user property from the Qube to the qubesdb so it is available when starting X. This is the 1st part of a fix for issue https://github.com/QubesOS/qubes-issues/issues/2372
This adds the file-reflink storage driver. It is never selected
automatically for pool creation, especially not the creation of
'varlibqubes' (though it can be used if set up manually).
The code is quite small:
reflink.py lvm.py file.py + block-snapshot
sloccount 334 lines 447 (134%) 570 (171%)
Background: btrfs and XFS (but not yet ZFS) support instant copies of
individual files through the 'FICLONE' ioctl behind 'cp --reflink'.
Which file-reflink uses to snapshot VM image files without an extra
device-mapper layer. All the snapshots are essentially freestanding;
there's no functional origin vs. snapshot distinction.
In contrast to 'file'-on-btrfs, file-reflink inherently avoids
CoW-on-CoW. Which is a bigger issue now on R4.0, where even AppVMs'
private volumes are CoW. (And turning off the lower, filesystem-level
CoW for 'file'-on-btrfs images would turn off data checksums too, i.e.
protection against bit rot.)
Also in contrast to 'file', all storage features are supported,
including
- any number of revisions_to_keep
- volume.revert()
- volume.is_outdated
- online fstrim/discard
Example tree of a file-reflink pool - *-dirty.img are connected to Xen:
- /var/lib/testpool/appvms/foo/volatile-dirty.img
- /var/lib/testpool/appvms/foo/root-dirty.img
- /var/lib/testpool/appvms/foo/root.img
- /var/lib/testpool/appvms/foo/private-dirty.img
- /var/lib/testpool/appvms/foo/private.img
- /var/lib/testpool/appvms/foo/private.img@2018-01-02T03:04:05Z
- /var/lib/testpool/appvms/foo/private.img@2018-01-02T04:05:06Z
- /var/lib/testpool/appvms/foo/private.img@2018-01-02T05:06:07Z
- /var/lib/testpool/appvms/bar/...
- /var/lib/testpool/appvms/...
- /var/lib/testpool/template-vms/fedora-26/...
- /var/lib/testpool/template-vms/...
It looks similar to a 'file' pool tree, and in fact file-reflink is
drop-in compatible:
$ qvm-shutdown --all --wait
$ systemctl stop qubesd
$ sed 's/ driver="file"/ driver="file-reflink"/g' -i.bak /var/lib/qubes/qubes.xml
$ systemctl start qubesd
$ sudo rm -f /path/to/pool/*/*/*-cow.img*
If the user tries to create a fresh file-reflink pool on a filesystem
that doesn't support reflinks, qvm-pool will abort and mention the
'setup_check=no' option. Which can be passed to force a fallback on
regular sparse copies, with of course lots of time/space overhead. The
same fallback code is also used when initially cloning a VM from a
foreign pool, or from another file-reflink pool on a different
mountpoint.
'journalctl -fu qubesd' will show all file-reflink copy/rename/remove
operations on VM creation/startup/shutdown/etc.
When some expiring rules are present, it is necessary to reload firewall
when those rules expire. Previously systemd timer was used to trigger
this action, but since we have own daemon now, it isn't necessary
anymore - use this daemon for that.
Additionally automatically removing expired rules was completely broken
in R4.0.
FixesQubesOS/qubes-issues#1173
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
