As there are two possible approaches to define a domain's memory size -
one used with legacy, non-NUMA VMs configured in the <memory> element
and per-node based approach on NUMA machines - the user needs to make
sure that both are specified correctly in the NUMA case.
To avoid this burden on the user I'd like to replace the NUMA case with
automatic totaling of the memory size. To achieve this I need to replace
direct access to the virDomainMemtune's 'max_balloon' field with
two separate getters depending on the desired size.
The two sizes are needed as:
1) Startup memory size doesn't include memory modules in some
hypervisors.
2) After startup these count as the usable memory size.
Note that the comments for the functions are future aware and document
state that will be present after a few later patches.
It will not be possible to detach such device later. Also improve
logging in such cases.
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
A helper that never returns an error and treats bits out of bitmap range
as false.
Use it everywhere we use ignore_value on virBitmapGetBit, or loop over
the bitmap size.
In the old days of a global driver lock, it was necessary to unlock
the driver after a domain restore operation. When the global lock
was removed from the driver, some remnants were left behind in
libxlDomainRestoreFlags. Remove this unneeded (and incorrect) code.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
For stateless, client side drivers, it is never correct to
probe for secondary drivers. It is only ever appropriate to
use the secondary driver that is associated with the
hypervisor in question. As a result the ESX & HyperV drivers
have both been forced to do hacks where they register no-op
drivers for the ones they don't implement.
For stateful, server side drivers, we always just want to
use the same built-in shared driver. The exception is
virtualbox which is really a stateless driver and so wants
to use its own server side secondary drivers. To deal with
this virtualbox has to be built as 3 separate loadable
modules to allow registration to work in the right order.
This can all be simplified by introducing a new struct
recording the precise set of secondary drivers each
hypervisor driver wants
struct _virConnectDriver {
virHypervisorDriverPtr hypervisorDriver;
virInterfaceDriverPtr interfaceDriver;
virNetworkDriverPtr networkDriver;
virNodeDeviceDriverPtr nodeDeviceDriver;
virNWFilterDriverPtr nwfilterDriver;
virSecretDriverPtr secretDriver;
virStorageDriverPtr storageDriver;
};
Instead of registering the hypervisor driver, we now
just register a virConnectDriver instead. This allows
us to remove all probing of secondary drivers. Once we
have chosen the primary driver, we immediately know the
correct secondary drivers to use.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
The path to the pty of a Xen PV console is set only in
virDomainOpenConsole. But this is done too late. A call to
virDomainGetXMLDesc done before OpenConsole will not have the path to
the pty, but a call after OpenConsole will.
e.g. of the current issue.
Starting a domain with '<console type="pty"/>'
Then:
virDomainGetXMLDesc():
<devices>
<console type='pty'>
<target type='xen' port='0'/>
</console>
</devices>
virDomainOpenConsole()
virDomainGetXMLDesc():
<devices>
<console type='pty' tty='/dev/pts/30'>
<source path='/dev/pts/30'/>
<target type='xen' port='0'/>
</console>
</devices>
The patch intend to have the TTY path on the first call of GetXMLDesc.
This is done by setting up the path at domain start up instead of in
OpenConsole.
https://bugzilla.redhat.com/show_bug.cgi?id=1170743
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
The virDomainDefineXMLFlags and virDomainCreateXML APIs both
gain new flags allowing them to be told to validate XML.
This updates all the drivers to turn on validation in the
XML parser when the flags are set
Now that xenconfig supports parsing and formatting Xen's
XL config format, integrate it into the libxl driver's
connectDomainXML{From,To}Native functions.
Signed-off-by: Kiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
The virDomainDefParse* and virDomainDefFormat* methods both
accept the VIR_DOMAIN_XML_* flags defined in the public API,
along with a set of other VIR_DOMAIN_XML_INTERNAL_* flags
defined in domain_conf.c.
This is seriously confusing & error prone for a number of
reasons:
- VIR_DOMAIN_XML_SECURE, VIR_DOMAIN_XML_MIGRATABLE and
VIR_DOMAIN_XML_UPDATE_CPU are only relevant for the
formatting operation
- Some of the VIR_DOMAIN_XML_INTERNAL_* flags only apply
to parse or to format, but not both.
This patch cleanly separates out the flags. There are two
distint VIR_DOMAIN_DEF_PARSE_* and VIR_DOMAIN_DEF_FORMAT_*
flags that are used by the corresponding methods. The
VIR_DOMAIN_XML_* flags received via public API calls must
be converted to the VIR_DOMAIN_DEF_FORMAT_* flags where
needed.
The various calls to virDomainDefParse which hardcoded the
use of the VIR_DOMAIN_XML_INACTIVE flag change to use the
VIR_DOMAIN_DEF_PARSE_INACTIVE flag.
Now that xenconfig supports parsing and formatting Xen's
XL config format, integrate it into the libxl driver's
connectDomainXML{From,To}Native functions.
Signed-off-by: Kiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
This patch contains three domain cleanup improvements in the migration
finish phase, ensuring a domain is properly disposed when a failure is
detected or the migration is cancelled.
The check for virDomainObjIsActive is moved to libxlDomainMigrationFinish,
where cleanup can occur if migration failed and the domain is inactive.
The 'cleanup' label was missplaced in libxlDomainMigrationFinish, causing
a migrated domain to remain in the event of an error or cancelled migration.
In cleanup, the domain was not removed from the driver's list of domains.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Moving data reception of the perform phase of migration to a
thread introduces a race with the finish phase, where checking
if the domain is active races with the thread finishing the
perform phase. The race is easily solved by acquiring a job in
the finish phase, which must wait for the perform phase job to
complete.
While wrapping the finish phase in a job, noticed the virDomainObj
was being unlocked in a callee - libxlDomainMigrationFinish. Move
the unlocking to libxlDomainMigrateFinish3Params, where the lock
is acquired.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
To prepare for introducing a single global driver, rename the
virDriver struct to virHypervisorDriver and the registration
API to virRegisterHypervisorDriver()
There is no need to acquire the driver-wide lock in
libxlDomainDefineXML. When switching to jobs in the libxl
driver, most driver-wide locks were removed. The locking here
was preserved since I mistakenly thought virDomainObjListAdd
needed protection. This is not the case, so remove the
unnecessary locking.
Test suites using the port allocator don't want to have different
behaviour depending on whether a port is in use on the host. Add
a VIR_PORT_ALLOCATOR_SKIP_BIND_CHECK which test suites can use
to skip the bind() test. The port allocator will thus only track
ports in use by the test suite process itself. This is fine when
using the port allocator to generate guest configs which won't
actually be launched
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Code logic in libxlDomainAttachDeviceFlags and libxlDomainDetachDeviceFlags
is wrong with return value in error cases.
'ret' was being set to 0 if 'flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG' was
false. Then if something like virDomainDeviceDefParse() failed in the
VIR_DOMAIN_DEVICE_MODIFY_LIVE logic, the error would be reported but the
function would return success.
Signed-off-by: Chunyan Liu <cyliu@suse.com>
During migration, the libxl driver starts a modify job in the
begin phase, ending the job in the confirm phase. This is
essentially VIR_MIGRATE_CHANGE_PROTECTION semantics, but the
driver does not support that flag. Without CHANGE_PROTECTION
support, the job would never be terminated in error conditions
where migrate confirm phase is not executed. Further attempts
to modify the domain would result in failure to acquire a job
after LIBXL_JOB_WAIT_TIME.
Similar to the qemu driver, end the job in the begin phase.
Protecting the domain object across all phases of migration can
be done in a future patch adding CHANGE_PROTECTION support.
In libxlDomainMigrationPrepare(), a new virDomainObj is created
from the incoming domain def and added to the driver's domain
list, but never removed if there are subsequent failures during
the prepare phase.
targethost# virsh list --all
sourcehost# virsh migrate --live dom xen+ssh://targethost/system
error: operation failed: Fail to create socket for incoming migration.
targethost# virsh list --all
error: Failed to list domains
error: name in virGetDomain must not be NULL
After adding code to remove the domain on prepare failure, noticed
that libvirtd crashed due to double free of the virDomainDef. Similar
to the qemu driver, pass a pointer to virDomainDefPtr so it can be set
to NULL once a virDomainObj is created from it.
Replace:
if (virBufferError(&buf)) {
virBufferFreeAndReset(&buf);
virReportOOMError();
...
}
with:
if (virBufferCheckError(&buf) < 0)
...
This should not be a functional change (unless some callers
misused the virBuffer APIs - a different error would be reported
then)
So far, we only report an error if formatting the siblings bitmap
in NUMA topology fails.
Be consistent and always report error in virCapabilitiesFormatXML.
libxl does not support save, restore, or migrate on all architectures,
notably ARM. Detect whether libxl supports these operations using
LIBXL_HAVE_NO_SUSPEND_RESUME. If not supported, drop advertisement of
<migration_features>.
Found by Ian Campbell while improving Xen's OSSTEST infrastructure
http://lists.xen.org/archives/html/xen-devel/2014-06/msg02171.html
This simplifies the usage in {libxl,qemu}DomainGetNumaParameters
and it's needed for consistent error reporting in virBitmapFormat.
Also remove the forgotten ATTRIBUTE_NONNULL marker.
This patch adds initial migration support to the libxl driver,
using the VIR_DRV_FEATURE_MIGRATION_PARAMS family of migration
functions.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
To allow the test suite to creat the XML option object,
move the virDomainXMLOptionNew call into a libxlCreateXMLConf
method.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
With xend on the way out, installations may not even have
/usr/sbin/xend, which results in the following error when the
drivers are probed
2014-04-28 18:21:19.271+0000: 22129: error : virCommandWait:2426 :
internal error: Child process (/usr/sbin/xend status) unexpected exit
status 127: libvirt: error : cannot execute binary /usr/sbin/xend:
No such file or directory
Check for existence of /usr/sbin/xend before trying to run it with
the 'status' option.
Currently the driver only exposes the ability to connect to the serial console
of a Xen guest, which doesn't work for a PV guest. Since for an HVM guest the
serial devices are duplicated as consoles it is sufficient to just use the
console devices unconditionally.
Tested with the following bit of config XML:
<domain type='xen'>
...
<devices>
<console type='pty'>
<target type='xen'/>
</console>
</devices>
</domain>
I have observed and tested this on ARM but I believe it also applies to x86 PV
guests.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Clark Laughlin <clark.laughlin@linaro.org>
Since it is an abbreviation, PCI should always be fully
capitalized or full lower case, never Pci.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
There is a domain id in the virDomain structure as well as in the
virDomainObj structure. While the former can become stale the latter
is kept up to date. So it is safer to always (virDomainObjPtr)->def->id
internally.
This will fix issues seen when managing Xen guests through libvirt from
virt-manager (not being able to get domain info after define or reboot).
This was caused both though libxlDomainGetInfo() only but there were
a lot of places that might potentially cause issues, too.
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Commit d9f19c30d0 moved a lot of the
configuration setup into libxlDriverConfigNew().
However that tries to create the libxl/libxl-driver.log before the
libxl directory gets created in libxlStateInitialize().
This causes the daemon to fail on systems that have not had the directory
created before.
Move the code to create the libxl directory into libxlDriverConfigNew().
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Part of a series of cleanups to use new accessor methods.
* src/libxl/libxl_conf.c (libxlMakeDisk): Use accessors.
* src/libxl/libxl_driver.c (libxlDomainChangeEjectableMedia)
(libxlDomainAttachDeviceDiskLive): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Move the domain event handler and shutdown thread out of the main
driver module and into libxl_domain module
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Include a pointer to the libxl driver in libxlDomainObjPrivate
object so it can be used in the domain event handler and
shutdown thread.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Move libxlVmStart from libxl_driver to libxl_domain for
use by other libxl modules. For consistency, rename to
libxlDomainStart.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Move libxlFreeMem from libxl_driver to libxl_domain for
use by other libxl modules. For consistency, rename to
libxlDomainFreeMem.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Move libxlDoNodeGetInfo from libxl_driver to libxl_conf
for use by other libxl modules. For consistency, rename to
libxlDriverNodeGetInfo.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Move libxlDomEventsRegister from libxl_driver to libxl_domain for
use by other libxl modules. For consistency, rename to
libxlDomainEventsRegister.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Move libxlVmCleanup and libxlVmCleanupJob from libxl_driver to
libxl_domain for use by other libxl modules. For consistency,
rename to libxlDomainCleanup and libxlDomainCleanupJob.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Move libxlSaveImageOpen from libxl_driver to libxl_domain for
use by other libxl modules. For consistency, rename to
libxlDomainSaveImageOpen.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Any source file which calls the logging APIs now needs
to have a VIR_LOG_INIT("source.name") declaration at
the start of the file. This provides a static variable
of the virLogSource type.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
The libxl driver reads /proc/xen/capabilities to see if it
is on a Dom0 kernel. If that file does not even exist though,
an error is logged. Check for the file existance before trying
to read its contents to avoid the log message.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Right now we are parsing the XML as though it's live, which for example
will choke on hardcoded XML like:
<seclabel type='dynamic' model='selinux' relabel='yes'/>
Erroring with:
$ sudo virsh domxml-to-native qemu-argv f
error: XML error: security label is missing
All drivers are fixed, but only qemu was tested.
As soon as any guest mounts xenfs to /proc/xen, there is a capabilities
file in that directory. However it returns nothing when reading from it.
Change the test to actually check the contents of the file.
BugLink: http://bugs.launchpad.net/bugs/1248025
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Supporting sexpr in connectDomainXMLFromNative in the libxl driver
adds flexibility for users importing legacy Xen configuration into
libvirt. E.g. this patch allows importing previous xend-managed
domains from /var/lib/xend/domains/<dom-uuid>/config.sxp into the
libvirt libxl driver.
The shutdown handler may restart a domain when handling a reboot
event or when <on_*> is set to 'restart'. Restarting consists of
calling libxlVmCleanup followed by libxlVmStart. libxlVmStart will
emit a VIR_DOMAIN_EVENT_STARTED event, but the SHUTDOWN event is
not emitted until exiting the shutdown handler, after the STARTED
event.
This patch changes the logic a bit to queue the event at the start
of the shutdown action, ensuring it is queued before any subsequent
events that may be generated while executing the shutdown action.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
The libxl driver was ignoring the <on_*> domain event configuration,
causing e.g. a domain to be rebooted even when on_reboot is set to
destroy.
This patch honors the <on_*> configuration in the shutdown event
handler.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Dumping a domain's core can take considerable time. Use the
recently added job functions and unlock the virDomainObj while
dumping core.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Saving domain memory and cpu state can take considerable time.
Use the recently added job functions and unlock the virDomainObj
while saving the domain.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
When explicitly destroying a domain (libxlDomainDestroyFlags), or
handling an out-of-band domain shutdown event, cleanup the domain
in the context of a job. Introduce libxlVmCleanupJob to wrap
libxlVmCleanup in a job block.
Large balloon operation can be time consuming. Use the recently
added job functions and unlock the virDomainObj while ballooning.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Creating a large domain could potentially be time consuming. Use the
recently added job functions and unlock the virDomainObj while
the create operation is in progress.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
This function, which only has five call sites, simply calls
libxl_domain_destroy and libxlVmCleanup. Call those functions
directly at the call sites, allowing more control over how a
domain is destroyed and cleaned up. This patch maintains the
existing semantic, leaving changes to a subsequent patch.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
A small fix for the possiblitiy of jumping to an error path before
registering for domain events, preventing receiving important ones
like shutdown and death.
libxlDomainRestoreFlags acquires the driver lock while reading the
domain config from the save file and adding it to
libxlDriverPrivatePtr->domains. But virDomainObjList provides
self-locking APIs, so remove the needless driver locking.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Handling the domain shutdown event within the event handler seems
a bit unfair to libxl's event machinery. Domain "shutdown" could
take considerable time. E.g. if the shutdown reason is reboot,
the domain must be reaped and then started again.
Spawn a shutdown handler thread to do this work, allowing libxl's
event machinery to go about its business.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Due to some misunderstanding of requirements libxl places on timer
handling, I introduced the half-brained idea of maintaining a list
of timeouts that the driver could force to expire before freeing a
libxlDomainObjPrivate (and hence libxl_ctx). But testing all
the latest versions of Xen supported by the libxl driver (4.2.3,
4.3.1, 4.4.0 RC3), I see that libxl will handle this just fine and
there is no need to force expiration behind libxl's back. Indeed it
may be harmful to do so.
This patch removes the timer list, allowing libxl to handle cleanup
of its timer registrations.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
https://bugzilla.redhat.com/show_bug.cgi?id=1058839
Commit f9f56340 for CVE-2014-0028 almost had the right idea - we
need to check the ACL rules to filter which events to send. But
it overlooked one thing: the event dispatch queue is running in
the main loop thread, and therefore does not normally have a
current virIdentityPtr. But filter checks can be based on current
identity, so when libvirtd.conf contains access_drivers=["polkit"],
we ended up rejecting access for EVERY event due to failure to
look up the current identity, even if it should have been allowed.
Furthermore, even for events that are triggered by API calls, it
is important to remember that the point of events is that they can
be copied across multiple connections, which may have separate
identities and permissions. So even if events were dispatched
from a context where we have an identity, we must change to the
correct identity of the connection that will be receiving the
event, rather than basing a decision on the context that triggered
the event, when deciding whether to filter an event to a
particular connection.
If there were an easy way to get from virConnectPtr to the
appropriate virIdentityPtr, then object_event.c could adjust the
identity prior to checking whether to dispatch an event. But
setting up that back-reference is a bit invasive. Instead, it
is easier to delay the filtering check until lower down the
stack, at the point where we have direct access to the RPC
client object that owns an identity. As such, this patch ends
up reverting a large portion of the framework of commit f9f56340.
We also have to teach 'make check' to special-case the fact that
the event registration filtering is done at the point of dispatch,
rather than the point of registration. Note that even though we
don't actually use virConnectDomainEventRegisterCheckACL (because
the RegisterAny variant is sufficient), we still generate the
function for the purposes of documenting that the filtering
takes place.
Also note that I did not entirely delete the notion of a filter
from object_event.c; I still plan on using that for my upcoming
patch series for qemu monitor events in libvirt-qemu.so. In
other words, while this patch changes ACL filtering to live in
remote.c and therefore we have no current client of the filtering
in object_event.c, the notion of filtering in object_event.c is
still useful down the road.
* src/check-aclrules.pl: Exempt event registration from having to
pass checkACL filter down call stack.
* daemon/remote.c (remoteRelayDomainEventCheckACL)
(remoteRelayNetworkEventCheckACL): New functions.
(remoteRelay*Event*): Use new functions.
* src/conf/domain_event.h (virDomainEventStateRegister)
(virDomainEventStateRegisterID): Drop unused parameter.
* src/conf/network_event.h (virNetworkEventStateRegisterID):
Likewise.
* src/conf/domain_event.c (virDomainEventFilter): Delete unused
function.
* src/conf/network_event.c (virNetworkEventFilter): Likewise.
* src/libxl/libxl_driver.c: Adjust caller.
* src/lxc/lxc_driver.c: Likewise.
* src/network/bridge_driver.c: Likewise.
* src/qemu/qemu_driver.c: Likewise.
* src/remote/remote_driver.c: Likewise.
* src/test/test_driver.c: Likewise.
* src/uml/uml_driver.c: Likewise.
* src/vbox/vbox_tmpl.c: Likewise.
* src/xen/xen_driver.c: Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Coverity complains about default: label in libxl_driver.c not be able
to be reached. It's by design for the code and since it's not necessary
in the code nor does it elicit any compiler/make check warnings - just
remove it rather than adding a coverity[dead_error_begin] tag.
While I'm at it, lxc_driver.c and nodeinfo.c have the same design, so I
removed the default labels and the existing coverity tags.
I noticed that we allow virDomainGetVcpusFlags even for read-only
connections, but that with a flag, it can require guest agent
interaction. It is feasible that a malicious guest could
intentionally abuse the replies it sends over the guest agent
connection to possibly trigger a bug in libvirt's JSON parser,
or withhold an answer so as to prevent the use of the agent
in a later command such as a shutdown request. Although we
don't know of any such exploits now (and therefore don't mind
posting this patch publicly without trying to get a CVE assigned),
it is better to err on the side of caution and explicitly require
full access to any domain where the API requires guest interaction
to operate correctly.
I audited all commands that are marked as conditionally using a
guest agent. Note that at least virDomainFSTrim is documented
as needing a guest agent, but that such use is unconditional
depending on the hypervisor (so the existing domain:fs_trim ACL
should be sufficient there, rather than also requirng domain:write).
But when designing future APIs, such as the plans for obtaining
a domain's IP addresses, we should copy the approach of this patch
in making interaction with the guest be specified via a flag, and
use that flag to also require stricter access checks.
* src/libvirt.c (virDomainGetVcpusFlags): Forbid guest interaction
on read-only connection.
(virDomainShutdownFlags, virDomainReboot): Improve docs on agent
interaction.
* src/remote/remote_protocol.x
(REMOTE_PROC_DOMAIN_SNAPSHOT_CREATE_XML)
(REMOTE_PROC_DOMAIN_SET_VCPUS_FLAGS)
(REMOTE_PROC_DOMAIN_GET_VCPUS_FLAGS, REMOTE_PROC_DOMAIN_REBOOT)
(REMOTE_PROC_DOMAIN_SHUTDOWN_FLAGS): Require domain:write for any
conditional use of a guest agent.
* src/xen/xen_driver.c: Fix clients.
* src/libxl/libxl_driver.c: Likewise.
* src/uml/uml_driver.c: Likewise.
* src/qemu/qemu_driver.c: Likewise.
* src/lxc/lxc_driver.c: Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Ever since ACL filtering was added in commit 7639736 (v1.1.1), a
user could still use event registration to obtain access to a
domain that they could not normally access via virDomainLookup*
or virConnectListAllDomains and friends. We already have the
framework in the RPC generator for creating the filter, and
previous cleanup patches got us to the point that we can now
wire the filter through the entire object event stack.
Furthermore, whether or not domain:getattr is honored, use of
global events is a form of obtaining a list of networks, which
is covered by connect:search_domains added in a93cd08 (v1.1.0).
Ideally, we'd have a way to enforce connect:search_domains when
doing global registrations while omitting that check on a
per-domain registration. But this patch just unconditionally
requires connect:search_domains, even when no list could be
obtained, based on the following observations:
1. Administrators are unlikely to grant domain:getattr for one
or all domains while still denying connect:search_domains - a
user that is able to manage domains will want to be able to
manage them efficiently, but efficient management includes being
able to list the domains they can access. The idea of denying
connect:search_domains while still granting access to individual
domains is therefore not adding any real security, but just
serves as a layer of obscurity to annoy the end user.
2. In the current implementation, domain events are filtered
on the client; the server has no idea if a domain filter was
requested, and must therefore assume that all domain event
requests are global. Even if we fix the RPC protocol to
allow for server-side filtering for newer client/server combos,
making the connect:serach_domains ACL check conditional on
whether the domain argument was NULL won't benefit older clients.
Therefore, we choose to document that connect:search_domains
is a pre-requisite to any domain event management.
Network events need the same treatment, with the obvious
change of using connect:search_networks and network:getattr.
* src/access/viraccessperm.h
(VIR_ACCESS_PERM_CONNECT_SEARCH_DOMAINS)
(VIR_ACCESS_PERM_CONNECT_SEARCH_NETWORKS): Document additional
effect of the permission.
* src/conf/domain_event.h (virDomainEventStateRegister)
(virDomainEventStateRegisterID): Add new parameter.
* src/conf/network_event.h (virNetworkEventStateRegisterID):
Likewise.
* src/conf/object_event_private.h (virObjectEventStateRegisterID):
Likewise.
* src/conf/object_event.c (_virObjectEventCallback): Track a filter.
(virObjectEventDispatchMatchCallback): Use filter.
(virObjectEventCallbackListAddID): Register filter.
* src/conf/domain_event.c (virDomainEventFilter): New function.
(virDomainEventStateRegister, virDomainEventStateRegisterID):
Adjust callers.
* src/conf/network_event.c (virNetworkEventFilter): New function.
(virNetworkEventStateRegisterID): Adjust caller.
* src/remote/remote_protocol.x
(REMOTE_PROC_CONNECT_DOMAIN_EVENT_REGISTER)
(REMOTE_PROC_CONNECT_DOMAIN_EVENT_REGISTER_ANY)
(REMOTE_PROC_CONNECT_NETWORK_EVENT_REGISTER_ANY): Generate a
filter, and require connect:search_domains instead of weaker
connect:read.
* src/test/test_driver.c (testConnectDomainEventRegister)
(testConnectDomainEventRegisterAny)
(testConnectNetworkEventRegisterAny): Update callers.
* src/remote/remote_driver.c (remoteConnectDomainEventRegister)
(remoteConnectDomainEventRegisterAny): Likewise.
* src/xen/xen_driver.c (xenUnifiedConnectDomainEventRegister)
(xenUnifiedConnectDomainEventRegisterAny): Likewise.
* src/vbox/vbox_tmpl.c (vboxDomainGetXMLDesc): Likewise.
* src/libxl/libxl_driver.c (libxlConnectDomainEventRegister)
(libxlConnectDomainEventRegisterAny): Likewise.
* src/qemu/qemu_driver.c (qemuConnectDomainEventRegister)
(qemuConnectDomainEventRegisterAny): Likewise.
* src/uml/uml_driver.c (umlConnectDomainEventRegister)
(umlConnectDomainEventRegisterAny): Likewise.
* src/network/bridge_driver.c
(networkConnectNetworkEventRegisterAny): Likewise.
* src/lxc/lxc_driver.c (lxcConnectDomainEventRegister)
(lxcConnectDomainEventRegisterAny): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Ever since their introduction (commit 1509b80 in v0.5.0 for
virConnectDomainEventRegister, commit 4445723 in v0.8.0 for
virConnectDomainEventDeregisterAny), the event deregistration
functions have been documented as returning 0 on success;
likewise for older registration (only the newer RegisterAny
must return a non-zero callbackID). And now that we are
adding virConnectNetworkEventDeregisterAny for v1.2.1, it
should have the same semantics.
Fortunately, all of the stateful drivers have been obeying
the docs and returning 0, thanks to the way the remote_driver
tracks things (in fact, the RPC wire protocol is unable to
send a return value for DomainEventRegisterAny, at least not
without adding a new RPC number). Well, except for vbox,
which was always failing deregistration, due to failure to
set the return value to anything besides its initial -1.
But for local drivers, such as test:///default, we've been
returning non-zero numbers; worse, the non-zero numbers have
differed over time. For example, in Fedora 12 (libvirt 0.8.2),
calling Register twice would return 0 and 1 [the callbackID
generated under the hood]; while in Fedora 20 (libvirt 1.1.3),
it returns 1 and 2 [the number of callbacks registered for
that event type]. Since we have changed the behavior over
time, and since it differs by local vs. remote, we can safely
argue that no one could have been reasonably relying on any
particular behavior, so we might as well obey the docs, as well
as prepare callers that might deal with older clients to not be
surprised if the docs are not strictly followed.
For consistency, this patch fixes the code for all drivers,
even though it only makes an impact for vbox and for local
drivers. By fixing all drivers, future copy and paste from
a remote driver to a local driver is less likely to
reintroduce the bug.
Finally, update the testsuite to gain some coverage of the
issue for local drivers, including the first test of old-style
domain event registration via function pointer instead of
event id.
* src/libvirt.c (virConnectDomainEventRegister)
(virConnectDomainEventDeregister)
(virConnectDomainEventDeregisterAny): Clarify docs.
* src/libxl/libxl_driver.c (libxlConnectDomainEventRegister)
(libxlConnectDomainEventDeregister)
(libxlConnectDomainEventDeregisterAny): Match documentation.
* src/lxc/lxc_driver.c (lxcConnectDomainEventRegister)
(lxcConnectDomainEventDeregister)
(lxcConnectDomainEventDeregisterAny): Likewise.
* src/test/test_driver.c (testConnectDomainEventRegister)
(testConnectDomainEventDeregister)
(testConnectDomainEventDeregisterAny)
(testConnectNetworkEventDeregisterAny): Likewise.
* src/uml/uml_driver.c (umlConnectDomainEventRegister)
(umlConnectDomainEventDeregister)
(umlConnectDomainEventDeregisterAny): Likewise.
* src/vbox/vbox_tmpl.c (vboxConnectDomainEventRegister)
(vboxConnectDomainEventDeregister)
(vboxConnectDomainEventDeregisterAny): Likewise.
* src/xen/xen_driver.c (xenUnifiedConnectDomainEventRegister)
(xenUnifiedConnectDomainEventDeregister)
(xenUnifiedConnectDomainEventDeregisterAny): Likewise.
* src/network/bridge_driver.c
(networkConnectNetworkEventDeregisterAny): Likewise.
* tests/objecteventtest.c (testDomainCreateXMLOld): New test.
(mymain): Run it.
(testDomainCreateXML): Check return values.
Signed-off-by: Eric Blake <eblake@redhat.com>
By actually removing the <vcpupin> element (from within the
<cputune> section) from the XML, rather than jus update it with
a fully set vcpu affinity mask.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
And use it to implement libxlDomainPinVcpu(), similarly to what
happens in the QEMU driver. This way, it is possible to both
query and change the vcpu affinity of a persistent but not
running domain.
In face, before this patch, we have:
# virsh list --all
Id Name State
----------------------------------------------------
5 debian_32 running
- fedora20_64 shut off
# virsh vcpupin fedora20_64 0 2-4 --current
error: this function is not supported by the connection driver: virDomainPinVcpuFlags
After (same situation as above):
# virsh vcpupin fedora20_64 0 2-4 --current
# virsh vcpupin fedora20_64 0
VCPU: CPU Affinity
----------------------------------
0: 2-4
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
So that it is possible to query vcpu related information of
a persistent but not running domain, like it is for the QEMU
driver.
In fact, before this patch, we have:
# virsh list --all
Id Name State
----------------------------------------------------
5 debian_32 running
- fedora20_64 shut off
# virsh vcpuinfo fedora20_64
error: this function is not supported by the connection driver: virDomainGetVcpuPinInfo
After (same situation as above, i.e., fedora20_64 not running):
# virsh vcpuinfo fedora20_64
VCPU: 0
CPU: N/A
State: N/A
CPU time N/A
CPU Affinity: yyyyyyyy
VCPU: 1
CPU: N/A
State: N/A
CPU time N/A
CPU Affinity: yyyyyyyy
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
by, in libxlDomainGetNumaParameters(), calling libxl_bitmap_init() as soon as
possible, which avoids getting to 'cleanup:', where libxl_bitmap_dispose()
happens, without having initialized the nodemap, and hence crashing after some
invalid free()-s:
# ./daemon/libvirtd -v
*** Error in `/home/xen/libvirt.git/daemon/.libs/lt-libvirtd': munmap_chunk(): invalid pointer: 0x00007fdd42592666 ***
======= Backtrace: =========
/lib64/libc.so.6(+0x7bbe7)[0x7fdd3f767be7]
/lib64/libxenlight.so.4.3(libxl_bitmap_dispose+0xd)[0x7fdd2c88c045]
/home/xen/libvirt.git/daemon/.libs/../../src/.libs/libvirt_driver_libxl.so(+0x12d26)[0x7fdd2caccd26]
/home/xen/libvirt.git/src/.libs/libvirt.so.0(virDomainGetNumaParameters+0x15c)[0x7fdd4247898c]
/home/xen/libvirt.git/daemon/.libs/lt-libvirtd(+0x1d9a2)[0x7fdd42ecc9a2]
/home/xen/libvirt.git/src/.libs/libvirt.so.0(virNetServerProgramDispatch+0x3da)[0x7fdd424e9eaa]
/home/xen/libvirt.git/src/.libs/libvirt.so.0(+0x1a6f38)[0x7fdd424e3f38]
/home/xen/libvirt.git/src/.libs/libvirt.so.0(+0xa81e5)[0x7fdd423e51e5]
/home/xen/libvirt.git/src/.libs/libvirt.so.0(+0xa783e)[0x7fdd423e483e]
/lib64/libpthread.so.0(+0x7c53)[0x7fdd3febbc53]
/lib64/libc.so.6(clone+0x6d)[0x7fdd3f7e1dbd]
Signed-off-by: Dario Faggili <dario.faggioli@citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Starting from commit 2e82c18c in Xen (will be included in Xen 4.4)
both libxl_get_max_cpus() and libxl_get_max_nodes() start returning
a proper libxl error code, in case of failure. This patch fixes
this in the libxl driver.
Note that, although it is now basically impossible for them to return
0, that would, theoretically, still be wrong. Also, checking that the
returned value is '<= 0' makes the code correct for both Xen 4.4 and
Xen 4.3 (and 4.2), and that is why we go for it (rather than
just '< 0').
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Martin Kletzander <mkletzan@redhat.com>
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
Most of our code base uses space after comma but not before;
fix the remaining uses before adding a syntax check.
* src/libxl/libxl_driver.c: Consistently use commas.
* src/xen/xend_internal.c: Likewise.
* src/xen/xs_internal.c: Likewise.
* src/xenapi/xenapi_driver.c: Likewise.
* src/xenapi/xenapi_utils.c: Likewise.
* src/xenxs/xen_sxpr.c: Likewise.
* src/xenxs/xen_xm.c: Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
ifdef LIBXL_HAVE_DOMAIN_CREATE_RESTORE_PARAMS hides a multi-line body
for a brace-less else. Add braces to ensure proper logic is applied.
Without this fix, new domains cannot be started. Both
libxl_domain_create_new and libxl_domain_create_restore are called when
starting a new domain leading to this error:
libxl: error: libxl.c:324:libxl__domain_rename: domain with name "guest" already exists.
libxl: error: libxl_create.c:800:initiate_domain_create: cannot make domain: -6
Rather than casting the virBitmap pointer to uint8_t* and then using
the structure contents as a byte array, use the virBitmap API to determine
the bitmap size and test each bit.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
in recently xen commit: 7051d5c8, there is a api changes in
libxl_domain_create_restore.
Author: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Thu Oct 10 12:23:10 2013 +0100
tools/migrate: Fix regression when migrating from older version of Xen
use the macro LIBXL_HAVE_DOMAIN_CREATE_RESTORE_PARAMS in libxl.h
in order to make libvirt could compile with old and new xen.
the params checkpointed_stream is useful if libvirt libxl driver
support migration. for new, set it as zero.
Signed-off-by: Bamvor Jian Zhang <bjzhang@suse.com>
According to the following valgrind output, there seems to be a
invalid limit for the iterator (captured on Fedora 19):
==3945== Invalid read of size 1
==3945== at 0x1E1FA410: libxlVmStart (libxl_driver.c:475)
==3945== by 0x1E1FAD9A: libxlDomainCreateWithFlags (libxl_driver.c:2633)
==3945== by 0x5187D46: virDomainCreate (libvirt.c:9439)
==3945== by 0x13BAA6: remoteDispatchDomainCreateHelper (remote_dispatch.h:2910)
==3945== by 0x51DE5B9: virNetServerProgramDispatch (virnetserverprogram.c:435)
==3945== by 0x51D93E7: virNetServerHandleJob (virnetserver.c:165)
==3945== by 0x50F5BF4: virThreadPoolWorker (virthreadpool.c:144)
==3945== by 0x50F5670: virThreadHelper (virthreadpthread.c:161)
==3945== by 0x8046C52: start_thread (pthread_create.c:308)
==3945== by 0x8758E1C: clone (clone.S:113)
==3945== Address 0x23424d81 is 0 bytes after a block of size 1 alloc'd
==3945== at 0x4A08121: calloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==3945== by 0x50B1F8C: virAllocN (viralloc.c:189)
==3945== by 0x1E1FA3CA: libxlVmStart (libxl_driver.c:468)
==3945== by 0x1E1FAD9A: libxlDomainCreateWithFlags (libxl_driver.c:2633)
==3945== by 0x5187D46: virDomainCreate (libvirt.c:9439)
==3945== by 0x13BAA6: remoteDispatchDomainCreateHelper (remote_dispatch.h:2910)
==3945== by 0x51DE5B9: virNetServerProgramDispatch (virnetserverprogram.c:435)
==3945== by 0x51D93E7: virNetServerHandleJob (virnetserver.c:165)
==3945== by 0x50F5BF4: virThreadPoolWorker (virthreadpool.c:144)
==3945== by 0x50F5670: virThreadHelper (virthreadpthread.c:161)
==3945== by 0x8046C52: start_thread (pthread_create.c:308)
==3945== by 0x8758E1C: clone (clone.S:113)
==3945==
Related: https://bugzilla.redhat.com/show_bug.cgi?id=1013045
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
No need to check if privileged when reading hostsysinfo, since
that check was already done in libxlDriverShouldLoad(). The
libxl driver fails to load if not privileged.
John Ferlan reported the following Coverity warning:
In libxlDomainCoreDump() Coverity has noted a FORWARD_NULL reference:
2004 if ((flags & VIR_DUMP_CRASH) && !vm->persistent) {
2005 virDomainObjListRemove(driver->domains, vm);
(20) Event assign_zero: Assigning: "vm" = "NULL".
Also see events: [var_deref_model]
2006 vm = NULL;
2007 }
2008
2009 ret = 0;
2010
2011 cleanup_unpause:
(21) Event var_deref_model: Passing null pointer "vm" to function
"virDomainObjIsActive(virDomainObjPtr)", which dereferences it. [details]
Also see events: [assign_zero]
2012 if (virDomainObjIsActive(vm) && paused) {
2013 if (libxl_domain_unpause(priv->ctx, dom->id) != 0) {
2014 virReportError(VIR_ERR_INTERNAL_ERROR,
Removing the vm from domain obj list and setting it to NULL can be
done in the previous 'if (flags & VIR_DUMP_CRASH)' conditional. Fix
the Coverity warning by ensuring vm is not NULL before testing if it
is still active.
Now that most fields of libxlDriverPrivate struct are immutable
or self-locking, there is no need to acquire the driver lock in
much of the libxl driver.
The libxlDriverPrivate struct contains an variety of data with
varying access needs. Similar to the QEMU and LXC drivers,
move all the static config data into a dedicated libxlDriverConfig
object. The only locking requirement is to hold the driver lock
while obtaining an instance of libxlDriverConfig. Once a reference
is held on the config object, it can be used completely lockless
since it is immutable.
libxlDomainGetInfo() uses the driver-wide libxl ctx when
it would be more appropriate to use the per-domain ctx
associated with the domain. Switch to using the per-domain
libxl ctx.
libxl version info is static data as far as the libxl driver
is concerned, so retrieve this info when the driver is initialized
and stash it in the libxlDriverPrivate object. Subsequently use
the stashed info instead of repeatedly calling libxl_get_version_info().
Detect early on in libxl driver initialization if the driver
should be loaded at all, avoiding needless initialization steps
that only have to be undone later. While at it, move the
detection to a helper function to improve readability.
After detecting that the driver should be loaded, subsequent
failures such as initializing the log stream, allocating libxl
ctx, etc. should be treated as failure to initialize the driver.
Create libxl_domain.[ch] and move all functions operating on
libxlDomainObjPrivate to these files. This will be useful for
future patches that e.g. add job support for libxlDomainObjPrivate.
More fallout from commit d72ef888. When reconnecting to running
domains, the libxl_ctx in libxlDomainObjPrivate was used before
initializing it, causing a segfault in libxl and consequently
crashing libvirtd.
Initialize the libxlDomainObjPrivate libxl_ctx in libxlReconnectDomain,
and while at it use this ctx in libxlReconnectDomain instead of the
driver-wide ctx.
There is a potential leak of a newly created libxlDomainObjPrivate
when subsequent allocation of the object's chrdev field fails.
Unref the object on such an error so that it is properly disposed.
Commit d72ef888 introduced a bug in the libxl driver that will
segfault libvirtd if libxl reports an error message, e.g. when
attempting to initialize the driver on a non-Xen system. I
assumed it was valid to pass a NULL logger to libxl_ctx_alloc(),
but that is not the case since any errors associated with the ctx
that are emitted by libxl will dereference the logger and crash
libvirtd.
Errors associated with the libxl driver-wide ctx could be useful
for debugging anyway, so create a 'libxl-driver.log' to capture
these errors.
introduced by cs 4b9eec50fe ("libxl: implement per
NUMA node free memory reporting"). What was wrong was that
libxl_get_numainfo() put in nr_nodes the actual number of
host NUMA nodes, not the highest node ID (like libnuma's
numa_max_node() does instead).
While at it, turn the failure of libxl_get_numainfo() from
a simple warning to a proper error, as requested during the
review of another patch of the original series.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Daniel P. Berrange <berrange@redhat.com>
Currently, only one log file is created by the libxl driver, with
all output from libxl for all domains going to this one file.
Create a per-domain log file based on domain name, making sifting
through the logs a bit easier. This required deferring libxl_ctx
allocation until starting the domain, which is fine since the
ctx is not used when the domain is inactive.
Tested-by: Dario Faggioli <dario.faggioli@citrix.com>
this patch introduce the console api in libxl driver for both pv and
hvm guest. and import and update the libxlMakeChrdevStr function
which was deleted in commit dfa1e1dd.
Signed-off-by: Bamvor Jian Zhang <bjzhang@suse.com>
The avail_vcpu bitmap has to be allocated before it can be used (using
the maximum allowed value for that). Then for each available VCPU the
bit in the mask has to be set (libxl_bitmap_set takes a bit position
as an argument, not the number of bits to set).
Without this, I would always only get one VCPU for guests created
through libvirt/libxl.
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Although, having it depending on Xen >= 4.3 (by using the proper
libxl feature flag).
Xen currently implements a NUMA placement policy which is basically
the same as the 'interleaved' policy of `numactl', although it can
be applied on a subset of the available nodes. We therefore hardcode
"interleave" as 'numa_mode', and we use the newly introduced libxl
interface to figure out what nodes a domain spans ('numa_nodeset').
With this change, it is now possible to query the NUMA node
affinity of a running domain:
[raistlin@Zhaman ~]$ sudo virsh --connect xen:/// list
Id Name State
----------------------------------------------------
23 F18_x64 running
[raistlin@Zhaman ~]$ sudo virsh --connect xen:/// numatune 23
numa_mode : interleave
numa_nodeset : 1
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
domainGetNumaParameters has a string typed parameter, hence it
is necessary for the libxl driver to support this.
This change implements the connectSupportsFeature hook for the
libxl driver, advertising that VIR_DRV_FEATURE_TYPED_PARAM_STRING
is supported.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Eric Blake <eblake@redhat.com>
Convert the type of loop iterators named 'i', 'j', k',
'ii', 'jj', 'kk', to be 'size_t' instead of 'int' or
'unsigned int', also santizing 'ii', 'jj', 'kk' to use
the normal 'i', 'j', 'k' naming
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Use virDomainObjListRemoveLocked instead of virDomainObjListRemove, as
driver->domains is already taken by virDomainObjListForEach.
Above deadlock can be triggered when libvirtd is started after some
domain have been started by hand (in which case driver will not find
libvirt-xml domain config).
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
By providing the implementation of nodeGetCellsFreeMemory for
the driver. This is all just a matter of properly formatting, in
a way that libvirt like, what Xen provides via libxl_get_numainfo().
[raistlin@Zhaman ~]$ sudo virsh --connect xen:/// freecell --all
0: 25004 KiB
1: 105848 KiB
--------------------
Total: 130852 KiB
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
libxl uses some xenstore entries for hints in memory management
(especially when starting new domain). This includes dom0 memory limit
and Xen free memory margin, based on current system state. Entries are
created at first function usage, so force such call at daemon startup,
which most likely will be before any domain startup.
Also prevent automatic memory management if dom0_mem= option passed to
xen hypervisor - it is known to be incompatible with autoballoon.
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
When creating a timer/event handler reference counting is used. So it could
be possible (in theory) that libxlDomainObjPrivateFree is called with
reference counting >1. The problem is that libxlDomainObjPrivateFree leave
the object in an invalid state with ctx freed (but still having dandling
pointer). This can lead timer/event handler to core.
This patch implements a dispose method for libxlDomainObjPrivate, and moves
freeing the libxl ctx to the dispose method, ensuring the ctx is valid while
the object's reference count is > 0.
Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Currently, the libxl driver reports a connection type of "xenlight".
To be compatible with the legacy Xen driver, it should return "Xen".
Note: I noticed this while testing the libxl driver on OpenStack.
After switching my Xen compute nodes to use the libxl stack, I
could no longer launch instances on those nodes since
hypervisor_type was reported as "xenlight" instead of "xen".
libxl expects the event handler to free the event passed to it. From
libxl_event.h:
event becomes owned by the application and must be freed, either
by event_occurs or later
