This patch adds an element to QEMU's capability XML, to
show if the underlying QEMU binary supports the live disk
snapshotting or not.
This allows any client to know ahead of time if the feature
is available.
Without this information available, the only way to check
for the snapshot support is to request one and check for
errors.
Signed-off-by: Francesco Romani <fromani@redhat.com>
There is no keyboard support currently in libvirt.
For some platforms (PPC64 QEMU) this makes graphics unusable,
since the keyboard is not implicit and it can't be added via libvirt.
Signed-off-by: Li Zhang <zhlcindy@linux.vnet.ibm.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>
Add a new character device backend called 'spiceport' that uses
spice's channel for communications and apart from spicevmc can be used
as a backend for any character device from libvirt's point of view.
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
Add a new <timer> for the HyperV reference time counter enlightenment
and the iTSC reference page for Windows guests.
This feature provides a paravirtual approach to track timer events for
the guest (similar to kvmclock) with the option to use real hardware
clock on systems with a iTSC with compensation across various hosts.
According to the documentation describing various tunables for domain
timers not all the fields are supported by all the driver types. Express
these in the RNG:
- rtc, platform: Only these support the "track" attribute.
- tsc: only one to support "frequency" and "mode" attributes
- hpet, pit: tickpolicy/catchup attribute/element
- kvmclock: no extra attributes are supported
Additionally the attributes of the <catchup> element for
tickpolicy='catchup' are optional according to the parsing code. Express
this in the XML and fix a spurious space added while formatting the
<catchup> element and add tests for it.
Add support for specifying various types when doing snapshots. This will
later allow to do snapshots on network backed volumes. Disks of type
'volume' are not supported by snapshots (yet).
Also amend the test suite to check parsing of the various new disk
types that can now be specified.
spice-server offers an API to disable file transfer messages
on the agent channel between the client and the guest.
This is supported in qemu through the disable-agent-file-xfer option.
This patch exposes this option to libvirt.
Adds a new element 'filetransfer', with one property,
'enable', which accepts a boolean.
Default is enabled, for backward compatibility.
Depends on the capability exported in the first patch of the series.
Signed-off-by: Francesco Romani <fromani@redhat.com>
This patch introduces new xml elements under <blkiotune>,
we use these new elements to setup the throttle blkio
cgroup for domain. The new blkiotune node looks like this:
<blkiotune>
<device>
<path>/path/to/block</path>
<weight>1000</weight>
<read_iops_sec>10000</read_iops_sec>
<write_iops_sec>10000</write_iops_sec>
<read_bytes_sec>1000000</read_bytes_sec>
<write_bytes_sec>1000000</write_bytes_sec>
</device>
</blkiotune>
Signed-off-by: Guan Qiang <hzguanqiang@corp.netease.com>
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
When idmap was added to LXC, we forgot to cover it in the testsuite.
The schema was missing an <element> layer, and as a result,
virt-xml-validate was failing on valid dumpxml output.
Reported by Eduard - Gabriel Munteanu on IRC.
* docs/schemas/domaincommon.rng (idmap): Include <idmap> element,
and support interleaves.
* tests/lxcxml2xmldata/lxc-idmap.xml: New file.
* tests/lxcxml2xmltest.c (mymain): Test it.
Signed-off-by: Eric Blake <eblake@redhat.com>
AArch64 qemu has similar behavior as armv7l, like use of mmio etc.
This patch adds similar bypass checks what we have for armv7l to aarch64.
E.g. we are enabling mmio transport for Nicdev.
Making addDefaultUSB and addDefaultMemballoon to false etc.
V3:
- Adding missing domain rng schema for aarcg64 and test case in
testutilsqemu.c which was causing test suite failure
while running make check.
V2:
- Added testcase to qemuxml2argvtest as suggested
during review comments of V1.
V1:
- Initial patch.
Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
https://bugzilla.redhat.com/show_bug.cgi?id=1035118
When outputting the XML for the RNG device, the code didn't format the
PCI address info. Additionally the schema wasn't expecting the info
although it was being parsed and used internally. Fix those mistakes and
add test for the PCI info section.
In the 'directory' and 'netfs' storage pools, a user can see
both 'file' and 'dir' storage volume types, to know when they
can descend into a subdirectory. But in a network-based storage
pool, such as the upcoming 'gluster' pool, we use 'network'
instead of 'file', and did not have any counterpart for a
directory until this patch. Adding a new volume type
'network-dir' is better than reusing 'dir', because it makes
it clear that the only way to access 'network' volumes within
that container is through the network mounting (leaving 'dir'
for something accessible in the local file system).
* include/libvirt/libvirt.h.in (virStorageVolType): Expand enum.
* docs/formatstorage.html.in: Document it.
* docs/schemasa/storagevol.rng (vol): Allow new value.
* src/conf/storage_conf.c (virStorageVol): Use new value.
* src/qemu/qemu_command.c (qemuBuildVolumeString): Fix client.
* src/qemu/qemu_conf.c (qemuTranslateDiskSourcePool): Likewise.
* tools/virsh-volume.c (vshVolumeTypeToString): Likewise.
* src/storage/storage_backend_fs.c
(virStorageBackendFileSystemVolDelete): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Add support for a new <pool type='gluster'>, similar to
RBD and Sheepdog. Terminology wise, a gluster volume
forms a libvirt storage pool, within the gluster volume,
individual files are treated as libvirt storage volumes.
* docs/schemas/storagepool.rng (poolgluster): New pool type.
* docs/formatstorage.html.in: Document gluster.
* docs/storage.html.in: Likewise, and contrast it with netfs.
* tests/storagepoolxml2xmlin/pool-gluster.xml: New test.
* tests/storagepoolxml2xmlout/pool-gluster.xml: Likewise.
* tests/storagepoolxml2xmltest.c (mymain): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
I got annoyed at having to use both 'virsh vol-list $pool --details'
AND 'virsh vol-dumpxml $vol $pool' to learn if I had populated
the volume correctly. Since two-thirds of the data present in
virStorageVolGetInfo() already appears in virStorageVolGetXMLDesc(),
this just adds the remaining piece of information, as:
<volume type='...'>
...
</volume>
* docs/formatstorage.html.in: Document new <volume type=...>.
* docs/schemas/storagevol.rng (vol): Add it to RelaxNG.
* src/conf/storage_conf.h (virStorageVolTypeToString): Declare.
* src/conf/storage_conf.c (virStorageVolTargetDefFormat): Output
the metatype.
(virStorageVolDefParseXML): Parse it, for unit tests.
* tests/storagevolxml2xmlout/vol-*.xml: Update tests to match.
Signed-off-by: Eric Blake <eblake@redhat.com>
The RNG grammar did not allow arbitrary interleaving, which makes
it harder than necessary to create a new volume from handwritten XML.
(Compare also to commit caf516db for pools).
* docs/schemas/storagevol.rng: Support interleaving.
* tests/storagevolxml2xmlin/vol-file-backing.xml: Test it.
Signed-off-by: Eric Blake <eblake@redhat.com>
Older xmllint version don't allow such characters in datatype anyURI.
In order not to change too much, I'm suggesting making a choice of
anyURI or 'absPathName' which should be fine (checked with upstream
and that old xmllint, both work fine).
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
$ touch /var/lib/libvirt/images/'a<b>c'
$ virsh pool-refresh default
$ virsh vol-dumpxml 'a<b>c' default | head -n2
<volume>
<name>a<b>c</name>
Oops. That's not valid XML. And when we fix the XML
generation, it fails RelaxNG validation.
I'm also tired of seeing <key>(null)</key> in the example
output for volume xml; while we used NULLSTR() to avoid
a NULL deref rather than relying on glibc's printf
extension behavior, it's even better if we avoid the issue
in the first place. But this requires being careful that
we don't invalidate any storage backends that were relying
on key being unassigned during virStoragVolCreateXML[From].
I would have split this into two patches (one for escaping,
one for avoiding <key>(null)</key>), but since they both
end up touching a lot of the same test files, I ended up
merging it into one.
Note that this patch allows pretty much any volume name
that can appear in a directory (excluding . and .. because
those are special), but does nothing to change the current
(unenforced) RelaxNG claim that pool names will consist
only of letters, numbers, _, -, and +. Tightening the C
code to match RelaxNG patterns and/or relaxing the grammar
to match the C code for pool names is a task for another
day (but remember, we DID recently tighten C code for
domain names to exclude a leading '.').
* src/conf/storage_conf.c (virStoragePoolSourceFormat)
(virStoragePoolDefFormat, virStorageVolTargetDefFormat)
(virStorageVolDefFormat): Escape user-controlled strings.
(virStorageVolDefParseXML): Parse key, for use in unit tests.
* src/storage/storage_driver.c (storageVolCreateXML)
(storageVolCreateXMLFrom): Ensure parsed key doesn't confuse
volume creation.
* docs/schemas/basictypes.rng (volName): Relax definition.
* tests/storagepoolxml2xmltest.c (mymain): Test it.
* tests/storagevolxml2xmltest.c (mymain): Likewise.
* tests/storagepoolxml2xmlin/pool-dir-naming.xml: New file.
* tests/storagepoolxml2xmlout/pool-dir-naming.xml: Likewise.
* tests/storagevolxml2xmlin/vol-file-naming.xml: Likewise.
* tests/storagevolxml2xmlout/vol-file-naming.xml: Likewise.
* tests/storagevolxml2xmlout/vol-*.xml: Fix fallout.
Signed-off-by: Eric Blake <eblake@redhat.com>
While trying to compare netfs against my new gluster pool, I
discovered two things:
virt-xml-validate chokes on valid xml produced by 'virsh pool-dumpxml'
[yet another reason that ALL patches that add new xml should be adding
corresponding tests]
When using glusterfs FUSE mounts, you cannot access a subdirectory
of a gluster volume. The recommended workaround in the gluster
community is to mount the volume to an intermediate location, then
bind-mount the desired subdirectory to the final location. Maybe
we should teach libvirt to do bind-mounting, but for now I chose to
just document the limitation.
* docs/storage.html.in: Improve documentation.
* docs/schemas/storagepool.rng (sourcefmtnetfs): Allow all
formats, and drop redundant info-vendor.
* tests/storagepoolxml2xmltest.c (mymain): New test.
* tests/storagepoolxml2xmlin/pool-netfs-gluster.xml: New file.
* tests/storagepoolxml2xmlout/pool-netfs-gluster.xml: Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
The linux kernel recently added support for paravirtual spinlock
handling to avoid performance regressions on overcomitted hosts. This
feature needs to be turned in the hypervisor so that the guest OS is
notified about the possible support.
This patch adds a new feature "paravirt-spinlock" to the XML and
supporting code to enable the "kvm_pv_unhalt" pseudo CPU feature in
qemu.
https://bugzilla.redhat.com/show_bug.cgi?id=1008989
Expand the "secmodel" XML fragment of "host" with a sequence of
baselabel's which describe the default security context used by
libvirt with a specific security model and virtualization type:
<secmodel>
<model>selinux</model>
<doi>0</doi>
<baselabel type='kvm'>system_u:system_r:svirt_t:s0</baselabel>
<baselabel type='qemu'>system_u:system_r:svirt_tcg_t:s0</baselabel>
</secmodel>
<secmodel>
<model>dac</model>
<doi>0</doi>
<baselabel type='kvm'>107:107</baselabel>
<baselabel type='qemu'>107:107</baselabel>
</secmodel>
"baselabel" is driver-specific information, e.g. in the DAC security
model, it indicates USER_ID:GROUP_ID.
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
The RNG grammar did not allow arbitrary interleaving, which makes
it harder than necessary to create a new pool from handwritten XML.
* docs/schemas/storagepool.rng: Allow interleaving.
* tests/storagepoolxml2xmlin/pool-sheepdog.xml: Test interleave.
* tests/storagepoolxml2xmlin/pool-iscsi-auth.xml: Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Since 76b644c when the support for RAM filesystems was introduced,
libvirt accepted the following XML:
<source usage='1024' unit='KiB'/>
This was parsed correctly and internally stored in bytes, but it
was formatted as (with an extra 's'):
<source usage='1024' units='KiB'/>
When read again, this was treated as if the units were missing,
meaning libvirt was unable to parse its own XML correctly.
The usage attribute was documented as being in KiB, but it was not
scaled if the unit was missing. Transient domains still worked,
because this was balanced by an extra 'k' in the mount options.
This patch:
Changes the parser to use 'units' instead of 'unit', as the latter
was never documented (fixing persistent domains) and some programs
(libvirt-glib, libvirt-sandbox) already parse the 'units' attribute.
Removes the extra 'k' from the tmpfs mount options, which is needed
because now we parse our own XML correctly.
Changes the default input unit to KiB to match documentation, fixing:
https://bugzilla.redhat.com/show_bug.cgi?id=1015689
Commit id 'c4a4603de' added an output <path> to the nodedev xml, but
did not update the schema.
This resulted in the failure of the 'virt-xml-validate' on a file
generated by 'virsh nodedev-dumpxml pci_0000_00_00_0' (for example).
This was found/seen by running autotest on my host.
This resolves one of the issues in:
https://bugzilla.redhat.com/show_bug.cgi?id=1003983
This device is identical to qemu's "intel-hda" device (known as "ich6"
in libvirt), but has a different PCI device ID (which matches the ID
of the hda audio built into the ich9 chipset, of course). It's not
supported in earlier versions of qemu, so it requires a capability
bit.
Useful to set custom forwarders instead of using the contents of
/etc/resolv.conf. It helps me to setup dnsmasq as local nameserver to
resolve VM domain names from domain 0, when domain option is used.
Signed-off-by: Diego Woitasen <diego.woitasen@vhgroup.net>
Signed-off-by: Eric Blake <eblake@redhat.com>
Currently the XML parser already allows the following syntax:
<disk type='block' device='cdrom'>
<source startupPolicy='optional'/>
<target dev='hda' bus='ide'/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
But it if the dev value is NULL then it would not have the leading
"<source ", resulting in invalid XML.
qemu/KVM also supports a tftp URL while specifying the cdrom ISO image.
The xml should be as following:
<disk type='network' device='cdrom'>
<source protocol='tftp' name='/url/path'>
<host name='host.name' port='69'/>
</source>
</disk>
Signed-off-by: Aline Manera <alinefm@br.ibm.com>
The ftps protocol is another protocol supported by qemu/KVM while specifying
the cdrom ISO image.
The xml should be as following:
<disk type='network' device='cdrom'>
<source protocol='ftps' name='/url/path'>
<host name='host.name' port='990'/>
</source>
</disk>
Signed-off-by: Aline Manera <alinefm@br.ibm.com>
The https protocol is also accepted by qemu/KVM when specifying the cdrom ISO
image.
The xml should be as following:
<disk type='network' device='cdrom'>
<source protocol='https' name='/url/path'>
<host name='host.name' port='443'/>
</source>
</disk>
Signed-off-by: Aline Manera <alinefm@br.ibm.com>
Commits 905629f4 and 1716e7a6 have added support for specifying
an IPv4 range and a port range to be used by NAT:
<forward mode='nat'>
<nat>
<address start='10.20.30.40' end='10.20.30.44'/>
<port start='60000' end='65432'/>
</nat>
</forward>
https://bugzilla.redhat.com/show_bug.cgi?id=1004364
This corresponds to '-sd' and '-drive if=sd' on the qemu command line.
Needed for many ARM boards which don't provide any other way to
pass in storage.
Add an attribute named 'removable' to the 'target' element of disks,
which controls the removable flag. For instance, on a Linux guest it
controls the value of /sys/block/$dev/removable. This option is only
valid for USB disks (i.e. bus='usb'), and its default value is 'off',
which is the same behaviour as before.
To achieve this, 'removable=on' (or 'off') is appended to the '-device
usb-storage' parameter sent to qemu when adding a USB disk via
'-disk'. A capability flag QEMU_CAPS_USB_STORAGE_REMOVABLE was added
to keep track if this option is supported by the qemu version used.
Bug: https://bugzilla.redhat.com/show_bug.cgi?id=922495
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
<controller type='pci' index='0' model='pci-root'>
<pcihole64 unit='KiB'>1048576</pcihole64>
</controller>
It can be used to adjust (or disable) the size of the 64-bit
PCI hole. The size attribute is in kilobytes (different unit
can be specified on input), but it gets rounded up to
the nearest GB by QEMU.
Disabling it will be needed for guests that crash with the
64-bit PCI hole (like Windows XP), see:
https://bugzilla.redhat.com/show_bug.cgi?id=990418
The ftp protocol is already recognized by qemu/KVM so add this support to
libvirt as well.
The xml should be as following:
<disk type='network' device='cdrom'>
<source protocol='ftp' name='/url/path'>
<host name='host.name' port='21'/>
</source>
</disk>
Signed-off-by: Aline Manera <alinefm@br.ibm.com>
QEMU/KVM already allows a HTTP URL for the cdrom ISO image so add this support
to libvirt as well.
The xml should be as following:
<disk type='network' device='cdrom'>
<source protocol='http' name='/url/path'>
<host name='host.name' port='80'/>
</source>
</disk>
Signed-off-by: Aline Manera <alinefm@br.ibm.com>
https://bugzilla.redhat.com/show_bug.cgi?id=924153
Commit 904e05a2 (v0.9.9) added a per-<disk> seclabel element with
an attribute relabel='no' in order to try and minimize the
impact of shutdown delays when an NFS server disappears. The idea
was that if a disk is on NFS and can't be labeled in the first
place, there is no need to attempt the (no-op) relabel on domain
shutdown. Unfortunately, the way this was implemented was by
modifying the domain XML so that the optimization would survive
libvirtd restart, but in a way that is indistinguishable from an
explicit user setting. Furthermore, once the setting is turned
on, libvirt avoids attempts at labeling, even for operations like
snapshot or blockcopy where the chain is being extended or pivoted
onto non-NFS, where SELinux labeling is once again possible. As
a result, it was impossible to do a blockcopy to pivot from an
NFS image file onto a local file.
The solution is to separate the semantics of a chain that must
not be labeled (which the user can set even on persistent domains)
vs. the optimization of not attempting a relabel on cleanup (a
live-only annotation), and using only the user's explicit notation
rather than the optimization as the decision on whether to skip
a label attempt in the first place. When upgrading an older
libvirtd to a newer, an NFS volume will still attempt the relabel;
but as the avoidance of a relabel was only an optimization, this
shouldn't cause any problems.
In the ideal future, libvirt will eventually have XML describing
EVERY file in the backing chain, with each file having a separate
<seclabel> element. At that point, libvirt will be able to track
more closely which files need a relabel attempt at shutdown. But
until we reach that point, the single <seclabel> for the entire
<disk> chain is treated as a hint - when a chain has only one
file, then we know it is accurate; but if the chain has more than
one file, we have to attempt relabel in spite of the attribute,
in case part of the chain is local and SELinux mattered for that
portion of the chain.
* src/conf/domain_conf.h (_virSecurityDeviceLabelDef): Add new
member.
* src/conf/domain_conf.c (virSecurityDeviceLabelDefParseXML):
Parse it, for live images only.
(virSecurityDeviceLabelDefFormat): Output it.
(virDomainDiskDefParseXML, virDomainChrSourceDefParseXML)
(virDomainDiskSourceDefFormat, virDomainChrDefFormat)
(virDomainDiskDefFormat): Pass flags on through.
* src/security/security_selinux.c
(virSecuritySELinuxRestoreSecurityImageLabelInt): Honor labelskip
when possible.
(virSecuritySELinuxSetSecurityFileLabel): Set labelskip, not
norelabel, if labeling fails.
(virSecuritySELinuxSetFileconHelper): Fix indentation.
* docs/formatdomain.html.in (seclabel): Document new xml.
* docs/schemas/domaincommon.rng (devSeclabel): Allow it in RNG.
* tests/qemuxml2argvdata/qemuxml2argv-seclabel-*-labelskip.xml:
* tests/qemuxml2argvdata/qemuxml2argv-seclabel-*-labelskip.args:
* tests/qemuxml2xmloutdata/qemuxml2xmlout-seclabel-*-labelskip.xml:
New test files.
* tests/qemuxml2argvtest.c (mymain): Run the new tests.
* tests/qemuxml2xmltest.c (mymain): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
This resolves the issue that prompted the filing of
https://bugzilla.redhat.com/show_bug.cgi?id=928638
(although the request there is for something much larger and more
general than this patch).
commit f3868259ca disabled the
forwarding to upstream DNS servers of unresolved DNS requests for
names that had no domain, but were just simple host names (no "."
character anywhere in the name). While this behavior is frowned upon
by DNS root servers (that's why it was changed in libvirt), it is
convenient in some cases, and since dnsmasq can be configured to allow
it, it must not be strictly forbidden.
This patch restores the old behavior, but since it is usually
undesirable, restoring it requires specification of a new option in
the network config. Adding the attribute "forwardPlainNames='yes'" to
the <dns> elemnt does the trick - when that attribute is added to a
network config, any simple hostnames that can't be resolved by the
network's dnsmasq instance will be forwarded to the DNS servers listed
in the host's /etc/resolv.conf for an attempt at resolution (just as
any FQDN would be forwarded).
When that attribute *isn't* specified, unresolved simple names will
*not* be forwarded to the upstream DNS server - this is the default
behavior.
This PCI controller, named "dmi-to-pci-bridge" in the libvirt config,
and implemented with qemu's "i82801b11-bridge" device, connects to a
PCI Express slot (e.g. one of the slots provided by the pcie-root
controller, aka "pcie.0" on the qemu commandline), and provides 31
*non-hot-pluggable* PCI (*not* PCIe) slots, numbered 1-31.
Any time a machine is defined which has a pcie-root controller
(i.e. any q35-based machinetype), libvirt will automatically add a
dmi-to-pci-bridge controller if one doesn't exist, and also add a
pci-bridge controller. The reasoning here is that any useful domain
will have either an immediate (startup time) or eventual (subsequent
hot-plug) need for a standard PCI slot; since the pcie-root controller
only provides PCIe slots, we need to connect a dmi-to-pci-bridge
controller to it in order to get a non-hot-plug PCI slot that we can
then use to connect a pci-bridge - the slots provided by the
pci-bridge will be both standard PCI and hot-pluggable.
Since pci-bridge devices themselves can not be hot-plugged into a
running system (although you can hot-plug other devices into a
pci-bridge's slots), any new pci-bridge controller that is added can
(and will) be plugged into the dmi-to-pci-bridge as long as it has
empty slots available.
This patch is also changing the qemuxml2xml-pcie test from a "DO_TEST"
to a "DO_DIFFERENT_TEST". This is so that the "before" xml can omit
the automatically added dmi-to-pci-bridge and pci-bridge devices, and
the "after" xml can include it - this way we are testing if libvirt is
properly adding these devices.
This controller is implicit on q35 machinetypes. It provides 31 PCIe
(*not* PCI) slots as controller 0.
Currently there are no devices that can connect to pcie-root, and no
implicit pci controller on a q35 machine, so q35 is still
unusable. For a usable q35 system, we need to add a
"dmi-to-pci-bridge" pci controller, which can connect to pcie-root,
and provides standard pci slots that can be used to connect other
devices.
There are two ways to use a iSCSI LUN as disk source for qemu.
* The LUN's path as it shows up on host, e.g.
/dev/disk/by-path/ip-$ip:3260-iscsi-$iqn-fc18:iscsi.iscsi0-lun-1
* The libiscsi URI from the storage pool source element host attribute, e.g.
iscsi://demo.org:6000/iqn.1992-01.com.example/1
For a "volume" type disk, if the specified "pool" is of iscsi
type, we should support to use the LUN in either of above 2 ways.
That's why to introduce a new XML tag "mode" for the disk source
(libvirt should support iscsi pool with libiscsi, but it's another
new feature, which should be done later).
The "mode" can be either of "host" or "direct". Use "host" to indicate
use of the LUN with the path as it shows up on host. Use "direct" to
indicate to use it with the source pool host URI (future patches may support
to use network type libvirt storage too, e.g. Ceph)
