This patch adds a new attribute "rawio" to the "disk" element
of domain XML. Valid values of "rawio" attribute are "yes"
and "no".
rawio='yes' indicates the disk is desirous of CAP_SYS_RAWIO.
If you specify the following XML:
<disk type='block' device='lun' rawio='yes'>
...
</disk>
the domain will be granted CAP_SYS_RAWIO.
(of course, the domain have to be executed with root privilege)
NOTE:
- "rawio" attribute is only valid when device='lun'
- At the moment, any other disks you won't use rawio can use rawio.
Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
This patch addresses: https://bugzilla.redhat.com/show_bug.cgi?id=781562
Along with the "rombar" option that controls whether or not a boot rom
is made visible to the guest, qemu also has a "romfile" option that
allows specifying a binary file to present as the ROM BIOS of any
emulated or passthrough PCI device. This patch adds support for
specifying romfile to both passthrough PCI devices, and emulated
network devices that attach to the guest's PCI bus (just about
everything other than ne2k_isa).
One example of the usefulness of this option is described in the
bugzilla report: 82576 sriov network adapters don't provide a ROM BIOS
for the cards virtual functions (VF), but an image of such a ROM is
available, and with this ROM visible to the guest, it can PXE boot.
In libvirt's xml, the new option is configured like this:
<hostdev>
...
<rom file='/etc/fake/boot.bin'/>
...
</hostdev
(similarly for <interface>).
When support for the rombar option was added, it was only added for
PCI passthrough devices, configured with <hostdev>. The same option is
available for any network device that is attached to the guest's PCI
bus. This patch allows setting rombar for any PCI network device type.
After adding cases to test this to qemuxml2argv-hostdev-pci-rombar.*,
I decided to rename those files (to qemuxml2argv-pci-rom.*) to more
accurately reflect the additional tests, and also noticed that up to
now we've only been performing a domainschematest for that case, so I
added the "pci-rom" test to both qemuxml2argv and qemuxml2xml (and in
the process found some bugs whose fixes I squashed into previous
commits of this series).
Since these two items are now in the virDomainDeviceInfo struct, it
makes sense to parse/format them in the functions written to
parse/format that structure. Not all types of devices allow them, so
two internal flags are added to indicate when it is appropriate to do
so.
I was lucky - only one test case needed to be re-ordered!
QEMU supports a bunch of CPUID features that are tied to the kvm CPUID
nodes rather than the processor's. They are "kvmclock",
"kvm_nopiodelay", "kvm_mmu", "kvm_asyncpf". These are not known to
libvirt and their CPUID leaf might move if (for example) the Hyper-V
extensions are enabled. Hence their handling would anyway require some
special-casing.
However, among these the most useful is kvmclock; an additional
"property" of this feature is that a <timer> element is a better model
than a CPUID feature. Although, creating part of the -cpu command-line
from something other than the <cpu> XML element introduces some
ugliness.
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Applications can now insert custom nodes and hierarchies into domain
configuration XML. Although currently not enforced, applications are
required to use their own namespaces on every custom node they insert,
with only one top-level element per namespace.
This introduces new attribute wrpolicy with only supported
value as immediate. This will be an optional
attribute with no defaults. This helps specify whether
to skip the host page cache.
When wrpolicy is specified, meaning when wrpolicy=immediate
a writeback is explicitly initiated for the dirty pages in
the host page cache as part of the guest file write operation.
Usage:
<filesystem type='mount' accessmode='passthrough'>
<driver type='path' wrpolicy='immediate'/>
<source dir='/export/to/guest'/>
<target dir='mount_tag'/>
</filesystem>
Currently this only works with type='mount' for the QEMU/KVM driver.
Signed-off-by: Deepak C Shetty <deepakcs@linux.vnet.ibm.com>
qemuxml2argvtest sanitizes PATH to just /bin, but on at least
Fedora 16, dirname lives in /usr/bin instead. Regression
introduced in commit e7201afd.
* tests/qemuxml2argvdata/qemu.sh: Avoid forking a dirname call,
since dirname might not be in PATH after test sanitization.
* tests/qemuxml2argvdata/qemu-supported-cpus.sh: Likewise.
Diagnosed by Michal Privoznik.
In case a hypervisor doesn't support the exact CPU model requested by a
domain XML, we automatically fallback to a closest CPU model the
hypervisor supports (and make sure we add/remove any additional features
if needed). This patch adds 'fallback' attribute to model element, which
can be used to disable this automatic fallback.
We support <interface> of type "mcast", "server", and "client",
but the RNG schema for them are missed. Attribute "address" is
optional for "server" type. And these 3 types support
<mac address='MAC'/>, too.
Add four tests of the XML -> argv handling for the PPC64 pseries machine.
The first is just a basic test of a bare bones machine.
The three others test various aspects of the spapr-vio address handling.
It seems that currently we can't include network devices, doing so leads
to a segfault because the network driverState is not initialised. Working
around that leads us to the problem that the 'default' network doesn't
exist. So for now just leave network devices out.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
KVM will be able to use a PCI SCSI controller even on POWER. Let
the user specify the vSCSI controller by other means than a default.
After this patch, the QEMU driver will actually look at the model
and reject anything but auto, lsilogic and ibmvscsi.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The new introduced optional attribute "copy_on_read</code> controls
whether to copy read backing file into the image file. The value can
be either "on" or "off". Copy-on-read avoids accessing the same backing
file sectors repeatedly and is useful when the backing file is over a
slow network. By default copy-on-read is off.
QEMU does not support security_model for anything but 'path' fs driver type.
Currently in libvirt, when security_model ( accessmode attribute) is not
specified it auto-generates it irrespective of the fs driver type, which
can result in a qemu error for drivers other than path. This patch ensures
that the qemu cmdline is correctly generated by taking into account the
fs driver type.
Signed-off-by: Deepak C Shetty <deepakcs@linux.vnet.ibm.com>
In the past, generic SCSI commands issued from a guest to a virtio
disk were always passed through to the underlying disk by qemu, and
the kernel would also pass them on.
As a result of CVE-2011-4127 (see:
http://seclists.org/oss-sec/2011/q4/536), qemu now honors its
scsi=on|off device option for virtio-blk-pci (which enables/disables
passthrough of generic SCSI commands), and the kernel will only allow
the commands for physical devices (not for partitions or logical
volumes). The default behavior of qemu is still to allow sending
generic SCSI commands to physical disks that are presented to a guest
as virtio-blk-pci devices, but libvirt prefers to disable those
commands in the standard virtio block devices, enabling it only when
specifically requested (hopefully indicating that the requester
understands what they're asking for). For this purpose, a new libvirt
disk device type (device='lun') has been created.
device='lun' is identical to the default device='disk', except that:
1) It is only allowed if bus='virtio', type='block', and the qemu
version is "new enough" to support it ("new enough" == qemu 0.11 or
better), otherwise the domain will fail to start and a
CONFIG_UNSUPPORTED error will be logged).
2) The option "scsi=on" will be added to the -device arg to allow
SG_IO commands (if device !='lun', "scsi=off" will be added to the
-device arg so that SG_IO commands are specifically forbidden).
Guests which continue to use disk device='disk' (the default) will no
longer be able to use SG_IO commands on the disk; those that have
their disk device changed to device='lun' will still be able to use SG_IO
commands.
*docs/formatdomain.html.in - document the new device attribute value.
*docs/schemas/domaincommon.rng - allow it in the RNG
*tests/* - update the args of several existing tests to add scsi=off, and
add one new test that will test scsi=on.
*src/conf/domain_conf.c - update domain XML parser and formatter
*src/qemu/qemu_(command|driver|hotplug).c - treat
VIR_DOMAIN_DISK_DEVICE_LUN *almost* identically to
VIR_DOMAIN_DISK_DEVICE_DISK, except as indicated above.
Note that no support for this new device value was added to any
hypervisor drivers other than qemu, because it's unclear what it might
mean (if anything) to those drivers.
Implement the parsing and formatting of the XML addition of
the previous commit. The new XML doesn't affect qemu command
line, so we can now test round-trip XML->memory->XML handling.
I chose to reuse the existing structure, even though per-device
override doesn't use all of those fields, rather than create a
new structure, in order to reuse more code.
* src/conf/domain_conf.h (_virDomainDiskDef): Add seclabel member.
* src/conf/domain_conf.c (virDomainDiskDefFree): Free it.
(virSecurityLabelDefFree): New function.
(virDomainDiskDefFormat): Print it.
(virSecurityLabelDefFormat): Reduce output if model not present.
(virDomainDiskDefParseXML): Alter signature, and parse seclabel.
(virSecurityLabelDefParseXML): Split...
(virSecurityLabelDefParseXMLHelper): ...into new helper.
(virDomainDeviceDefParse, virDomainDefParseXML): Update callers.
* tests/qemuxml2argvdata/qemuxml2argv-seclabel-dynamic-override.args:
New file.
* tests/qemuxml2xmltest.c (mymain): Enhance test.
* tests/qemuxml2argvtest.c (mymain): Likewise.
When doing security relabeling, there are cases where a per-file
override might be appropriate. For example, with a static label
and relabeling, it might be appropriate to skip relabeling on a
particular disk, where the backing file lives on NFS that lacks
the ability to track labeling. Or with dynamic labeling, it might
be appropriate to use a custom (non-dynamic) label for a disk
specifically intended to be shared across domains.
The new XML resembles the top-level <seclabel>, but with fewer
options (basically relabel='no', or <label>text</label>):
<domain ...>
...
<devices>
<disk type='file' device='disk'>
<source file='/path/to/image1'>
<seclabel relabel='no'/> <!-- override for just this disk -->
</source>
...
</disk>
<disk type='file' device='disk'>
<source file='/path/to/image1'>
<seclabel relabel='yes'> <!-- override for just this disk -->
<label>system_u:object_r:shared_content_t:s0</label>
</seclabel>
</source>
...
</disk>
...
</devices>
<seclabel type='dynamic' model='selinux'>
<baselabel>text</baselabel> <!-- used for all devices without override -->
</seclabel>
</domain>
This patch only introduces the XML and documentation; future patches
will actually parse and make use of it. The intent is that we can
further extend things as needed, adding a per-device <seclabel> in
more places (such as the source of a console device), and possibly
allowing a <baselabel> instead of <label> for labeling where we want
to reuse the cNNN,cNNN pair of a dynamically labeled domain but a
different base label.
First suggested by Daniel P. Berrange here:
https://www.redhat.com/archives/libvir-list/2011-December/msg00258.html
* docs/schemas/domaincommon.rng (devSeclabel): New define.
(disk): Use it.
* docs/formatdomain.html.in (elementsDisks, seclabel): Document
the new XML.
* tests/qemuxml2argvdata/qemuxml2argv-seclabel-dynamic-override.xml:
New test, to validate RNG.
The RNG for <seclabel> was too strict - if it was present, then it
had to have sub-elements, even if those didn't make sense for the
given attributes. Also, we didn't have any tests of <seclabel>
parsing or XML output.
In this patch, I added more parsing tests than output tests (since
the output populates and/or reorders fields not present in certain
inputs). Making the RNG reliable is a precursor to using <seclabel>
variants in more places in the XML in later patches.
See also:
http://berrange.com/posts/2011/09/29/two-small-improvements-to-svirt-guest-configuration-flexibility-with-kvmlibvirt/
* docs/schemas/domaincommon.rng (seclabel): Tighten rules.
* tests/qemuxml2argvtest.c (mymain): New tests.
* tests/qemuxml2xmltest.c (mymain): Likewise.
* tests/qemuxml2argvdata/qemuxml2argv-seclabel-*.*: New files.
One of the xml tests in the test suite was created using a
now-deprecated qemu machine type ("fedora-13", which was only ever
valid for Fedora builds of qemu). Although strictly speaking it's not
necessary to replace it with an actual supported qemu machine type
(since the xml in question is never actually sent to qemu), this patch
changes it to the actually-supported "pc-0.13" just for general
tidiness. (Also, on some Fedora builds which contain a special patch
to rid the world of "fedora-13", having it mentioned in the test suite
will cause make check to fail.)
This adds per-device weights to <blkiotune>. Note that the
cgroups implementation only supports weights per block device,
and not per-file within the device; hence this option must be
global to the domain definition rather than tied to individual
<devices>/<disk> entries:
<domain ...>
<blkiotune>
<device>
<path>/path/to/block</path>
<weight>1000</weight>
</device>
</blkiotune>
..
This patch also adds a parameter --device-weights to virsh command
blkiotune for setting/getting blkiotune.weight_device for any
hypervisor that supports it. All <device> entries under
<blkiotune> are concatenated into a single string attribute under
virDomain{Get,Set}BlkioParameters, named "device_weight".
Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Add routines to generate -numa QEMU command line option based on
<numa> ... </numa> XML specifications.
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
This improves the support for qemu rbd devices by adding support for a few
key features (e.g., authentication) and cleaning up the way in which
rbd configuration options are passed to qemu.
An <auth> member of the disk source xml specifies how librbd should
authenticate. The username attribute is the Ceph/RBD user to authenticate as.
The usage or uuid attributes specify which secret to use. Usage is an
arbitrary identifier local to libvirt.
The old RBD support relied on setting an environment variable to
communicate information to qemu/librbd. Instead, pass those options
explicitly to qemu. Update the qemu argument parsing and tests
accordingly.
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Josh Durgin <josh.durgin@dreamhost.com>
While Xen only has a single paravirt console, UML, and
QEMU both support multiple paravirt consoles. The LXC
driver can also be trivially made to support multiple
consoles. This patch extends the XML to allow multiple
<console> elements in the XML. It also makes the UML
and QEMU drivers support this config.
* src/conf/domain_conf.c, src/conf/domain_conf.h: Allow
multiple <console> devices
* src/lxc/lxc_driver.c, src/xen/xen_driver.c,
src/xenxs/xen_sxpr.c, src/xenxs/xen_xm.c: Update for
internal API changes
* src/security/security_selinux.c, src/security/virt-aa-helper.c:
Only label consoles that aren't a copy of the serial device
* src/qemu/qemu_command.c, src/qemu/qemu_driver.c,
src/qemu/qemu_process.c, src/uml/uml_conf.c,
src/uml/uml_driver.c: Support multiple console devices
* tests/qemuxml2xmltest.c, tests/qemuxml2argvtest.c: Extra
tests for multiple virtio consoles. Set QEMU_CAPS_CHARDEV
for all console /channel tests
* tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-auto.args,
tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.args
tests/qemuxml2argvdata/qemuxml2argv-console-virtio.args: Update
for correct chardev syntax
* tests/qemuxml2argvdata/qemuxml2argv-console-virtio-many.args,
tests/qemuxml2argvdata/qemuxml2argv-console-virtio-many.xml: New
test file
Rather than making all clients of monitor commands that are JSON-only
check whether yajl support was compiled in, it is simpler to just
avoid setting the capability bit up front if we can't use the capability.
* src/qemu/qemu_capabilities.c (qemuCapsComputeCmdFlags): Only set
capability bit if we also have yajl library to use it.
* src/qemu/qemu_driver.c (qemuDomainReboot): Drop #ifdefs.
* src/qemu/qemu_process.c (qemuProcessStart): Likewise.
* tests/qemuhelptest.c (testHelpStrParsing): Pass test even
without yajl.
* tests/qemuxml2argvtest.c (mymain): Simplify use of json flag.
* tests/qemuxml2argvdata/qemuxml2argv-disk-drive-error-*.args:
Update expected results to match.
VirtFS allows the user to choose between path/handle based fs driver.
As of now, libvirt hardcoded path based driver only. This patch provides
a solution to allow user to choose between path/handle based fs driver.
Sample:
<filesystem type='mount'>
<driver type='handle'/>
<source dir='/folder/to/share1'/>
<target dir='mount_tag1'/>
</filesystem>
<filesystem type='mount'>
<driver type='path'/>
<source dir='/folder/to/share2'/>
<target dir='mount_tag2'/>
</filesystem>
Signed-off-by: Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Previously libvirt's disk device XML only had a single attribute,
error_policy, to control both read and write error policy, but qemu
has separate options for controlling read and write. In one case
(enospc) a policy is allowed for write errors but not read errors.
This patch adds a separate attribute that sets only the read error
policy. If just error_policy is set, it will apply to both read and
write error policy (previous behavior), but if the new rerror_policy
attribute is set, it will override error_policy for read errors only.
Possible values for rerror_policy are "stop", "report", and "ignore"
("report" is the qemu-controlled default for rerror_policy when
error_policy isn't specified).
For consistency, the value "report" has been added to the possible
values for error_policy as well.
commit 12062ab set rerror=ignore when error_policy="enospace" was
selected (since the rerror option in qemu doesn't accept "enospc", as
the werror option does).
After that patch was already pushed, Paolo Bonzini noticed it and
commented that leaving rerror at the default ("report") would be a
better choice. This patch corrects the problem - if error_policy =
"enospace" is given, rerror is left off the qemu commandline,
effectively setting it to "report". For other values, rerror is still
set to match werror.
Additionally, the parsing of error_policy was changed to no longer
erroneously allow "default" as a choice - as with most other
attributes, if you want the default setting, just don't specify an
error_policy.
Finally, two ommissions in the first patch were corrected - a
long-dormant qemuxml2argv test for enospace was enabled, and fixed to
pass, and the argv2xml parser in qemu_command.c was updated to
recognize the different spelling on the qemu commandline.
When support for was added for PCI multifunction cards (in commit
9f8baf, first included in libvirt 0.9.3), it was done by always
turning on the multifunction bit for all PCI devices. Since that time
it has been realized that this is not an ideal solution, and that the
multifunction bit must be selectively turned on. For example, see
https://bugzilla.redhat.com/show_bug.cgi?id=728174
and the discussion before and after
https://www.redhat.com/archives/libvir-list/2011-September/msg01036.html
This patch modifies multifunction support so that the multifunction=on
option is only added to the qemu commandline for a device if its PCI
<address> definition has the attribute "multifunction='on'", e.g.:
<address type='pci' domain='0x0000' bus='0x00'
slot='0x04' function='0x0' multifunction='on'/>
In practice, the multifunction bit should only be turned on if
function='0' AND other functions will be used in the same slot - it
usually isn't needed for functions 1-7 (although there are apparently
some exceptions, e.g. the Intel X53 according to the QEMU source
code), and should never be set if only function 0 will be used in the
slot. The test cases have been changed accordingly to illustrate.
With this patch in place, if a user attempts to assign multiple
functions in a slot without setting the multifunction bit for function
0, libvirt will issue an error when the domain is defined, and the
define operation will fail. In the future, we may decide to detect
this situation and automatically add multifunction=on to avoid the
error; even then it will still be useful to have a manual method of
turning on multifunction since, as stated above, there are some
devices that excpect it to be turned on for all functions in a slot.
A side effect of this patch is that attempts to use the same PCI
address for two different devices will now log an error (previously
this would cause the domain define operation to fail, but there would
be no log message generated). Because the function doing this log was
almost completely rewritten, I didn't think it worthwhile to make a
separate patch for that fix (the entire patch would immediately be
obsoleted).
This patch was made in response to:
https://bugzilla.redhat.com/show_bug.cgi?id=738095
In short, qemu's default for the rombar setting (which makes the
firmware ROM of a PCI device visible/not on the guest) was previously
0 (not visible), but they recently changed the default to 1
(visible). Unfortunately, there are some PCI devices that fail in the
guest when rombar is 1, so the setting must be exposed in libvirt to
prevent a regression in behavior (it will still require explicitly
setting <rom bar='off'/> in the guest XML).
rombar is forced on/off by adding:
<rom bar='on|off'/>
inside a <hostdev> element that defines a PCI device. It is currently
ignored for all other types of devices.
At the moment there is no clean method to determine whether or not the
rombar option is supported by QEMU - this patch uses the advice of a
QEMU developer to assume support for qemu-0.12+. There is currently a
patch in the works to put this information in the output of "qemu-kvm
-device pci-assign,?", but of course if we switch to keying off that,
we would lose support for setting rombar on all the versions of qemu
between 0.12 and whatever version gets that patch.
QEMU 0.13 introduced cache=unsafe for -drive, this patch exposes
it in the libvirt layer.
* Introduced a new QEMU capability flag ($prefix_CACHE_UNSAFE),
as even if $prefix_CACHE_V2 is set, we can't know if unsafe
is supported.
* Improved the reliability of qemu cache type detection.
The commit that prevents disk corruption on domain shutdown
(96fc478417) causes regression with QEMU
0.14.* and 0.15.* because of a regression bug in QEMU that was fixed
only recently in QEMU git. The affected versions of QEMU do not quit on
SIGTERM if started with -no-shutdown, which we use to implement fake
reboot. Since -no-shutdown tells QEMU not to quit automatically on guest
shutdown, domains started using the affected QEMU cannot be shutdown
properly and stay in a paused state.
This patch disables fake reboot feature on such QEMU by not using
-no-shutdown, which makes shutdown work as expected. However,
virDomainReboot will not work in this case and it will report "Requested
operation is not valid: Reboot is not supported with this QEMU binary".
It is important to be able to attach USB redirected devices to a
particular controller (one that supports USB2 for instance).
Without this patch, only the default bus was used.
<redirdev bus='usb' type='spicevmc'>
<address type='usb' bus='0' port='4'/>
</redirdev>
As discussed here:
https://www.redhat.com/archives/libvir-list/2011-August/msg00361.htmlhttps://www.redhat.com/archives/libvir-list/2011-August/msg00552.html
Adds snapshot attribute and transient sub-element:
<devices>
<disk type=... snapshot='no|internal|external'>
...
<transient/>
</disk>
</devices>
* docs/schemas/domaincommon.rng (snapshot): New define.
(disk): Add snapshot and persistent attributes.
* docs/formatdomain.html.in: Document them.
* src/conf/domain_conf.h (virDomainDiskSnapshot): New enum.
(_virDomainDiskDef): New fields.
* tests/qemuxml2argvdata/qemuxml2argv-disk-transient.xml: New
test of rng, no args counterpart until qemu support is complete.
* tests/qemuxml2argvdata/qemuxml2argv-disk-snapshot.args: New
file, snapshot attribute does not affect args.
* tests/qemuxml2argvdata/qemuxml2argv-disk-snapshot.xml: Likewise.
* tests/qemuxml2argvtest.c (mymain): Run new test.
QEMU uses USB bus name "usb.0" when using the legacy -usb argument.
If we want to allow USB devices to specify their addresses with legacy
-usb, we should either in case of legacy bus name drop the 0 from the
address bus, or just drop the 0 from device id. This patch does the
later.
Another solution would be to permit addressing on non-legacy USB
controllers only.
So that devices can be attached to hubs. Example, to attach to first
port of a usb-hub on port 1.
<hub type='usb'>
<address type='usb' bus='0' port='1'/>
</hub>
<input type='mouse' type='usb'>
<address type='usb' bus='0' port='1.1'/>
</hub>
also add a test entry
Created by copying from qemuxml2argv-disk-drive-v2-wb.*, then
s/writeback/directsync/. Hopefully this matches Osier's intentions.
* tests/qemuxml2argvdata/qemuxml2argv-disk-drive-cache-directsync.args:
* tests/qemuxml2argvdata/qemuxml2argv-disk-drive-cache-directsync.xml:
Add missing files needed by 'make check'.
In some versions of qemu, both virtio-blk-pci and virtio-net-pci
devices can have an event_idx setting that determines some details of
event processing. When it is enabled, it "reduces the number of
interrupts and exits for the guest". qemu will automatically enable
this feature when it is available, but there may be cases where this
new feature could actually make performance worse (NB: no such case
has been found so far).
As a safety switch in case such a situation is encountered in the
field, this patch adds a new attribute "event_idx" to the <driver>
element of both disk and interface devices. event_idx can be set to
"on" (to force event_idx on in case qemu has it disabled by default)
or "off" (for force event_idx off). In the case that event_idx support
isn't present in qemu, the attribute is ignored (this on the advice of
the qemu developer).
docs/formatdomain.html.in: document the new flag (marking it as
"don't mess with this!"
docs/schemas/domain.rng: add event_idx in appropriate places
src/conf/domain_conf.[ch]: add event_idx to parser and formatter
src/libvirt_private.syms: export
virDomainVirtioEventIdx(From|To)String
src/qemu/qemu_capabilities.[ch]: detect and report event_idx in
disk/net
src/qemu/qemu_command.c: add event_idx parameter to qemu commandline
when appropriate.
tests/qemuxml2argvdata/qemuxml2argv-event_idx.args,
tests/qemuxml2argvdata/qemuxml2argv-event_idx.xml,
tests/qemuxml2argvtest.c,
tests/qemuxml2xmltest.c: test cases for event_idx.
