Right now, the only way to get at the contents of a virBuffer is
to destroy it. But there are cases in my upcoming patches where
peeking at the contents makes life easier. I suppose this does
open up the potential for bad code to dereference a stale pointer,
by disregarding the docs that the return value is invalid on the
next virBuf operation, but such is life.
* src/util/buf.h (virBufferCurrentContent): New declaration.
* src/util/buf.c (virBufferCurrentContent): Implement it.
* src/libvirt_private.syms (buf.h): Export it.
* tests/virbuftest.c (testBufAutoIndent): Test it.
This fixes the build on 32bit systems which otherwise fails with:
virnetmessagetest.c: In function 'testMessageHeaderEncode':
virnetmessagetest.c:75:9: error: format '%zu' expects argument of type 'size_t', but argument 7 has type 'long unsigned int' [-Werror=format]
Currently, we are allocating buffer for RPC messages statically.
This is not such pain when RPC limits are small. However, if we want
ever to increase those limits, we need to allocate buffer dynamically,
based on RPC message len (= the first 4 bytes). Therefore we will
decrease our mem usage in most cases and still be flexible enough in
corner cases.
QEMU 1.1.0 has been officially released. With 1.1.0 QEMU went back to
three-digits version even for the initial release and I renamed the data
files to match this fact. They were generated with
qemu-system-x86_64 -help >tests/qemuhelpdata/qemu-1.1.0
qemu-system-x86_64 \
-device ? \
-device pci-assign,? \
-device virtio-blk-pci,? \
-device virtio-net-pci,? \
-device scsi-disk,? 2>tests/qemuhelpdata/qemu-1.1.0-device
I came across a bug that the command line generated for passthrough
of the host parallel port /dev/parport0 by libvirt for QEMU is incorrect.
It currently produces:
-chardev tty,id=charparallel0,path=/dev/parport0
-device isa-parallel,chardev=charparallel0,id=parallel0
The first parameter is "tty". It sould be "parport".
If I launch qemu with -chardev parport,... it works as expected.
I have already filled a bug report (
https://bugzilla.redhat.com/show_bug.cgi?id=823879 ), the topic was
already on the list some months ago:
https://www.redhat.com/archives/libvirt-users/2011-September/msg00095.html
Signed-off-by: Eric Blake <eblake@redhat.com>
It is possible to deadlock libvirt by having a domain with XML
longer than PIPE_BUF, and by writing a hook script that closes
stdin early. This is because libvirt was keeping a copy of the
child's stdin read fd open, which means the write fd in the
parent will never see EPIPE (remember, libvirt should always be
run with SIGPIPE ignored, so we should never get a SIGPIPE signal).
Since there is no error, libvirt blocks waiting for a write to
complete, even though the only reader is also libvirt. The
solution is to ensure that only the child can act as a reader
before the parent does any writes; and then dealing with the
fallout of dealing with EPIPE.
Thankfully, this is not a security hole - since the only way to
trigger the deadlock is to install a custom hook script, anyone
that already has privileges to install a hook script already has
privileges to do any number of other equally disruptive things
to libvirt; it would only be a security hole if an unprivileged
user could install a hook script to DoS a privileged user.
* src/util/command.c (virCommandRun): Close parent's copy of child
read fd earlier.
(virCommandProcessIO): Don't let EPIPE be fatal; the child may
be done parsing input.
* tests/commandhelper.c (main): Set up a SIGPIPE situation.
* tests/commandtest.c (test20): Trigger it.
* tests/commanddata/test20.log: New file.
Currently, monitoring QEMU virtual machines with standard Unix
sysadmin tools is harder than it has to be. The QEMU command line is
often miles long and mostly redundant, it's hard to tell which process
is which.
This patch reorders the QEMU -name argument to be the first, so it's
immediately visible in "ps x", htop and "atop -c" output.
Libtool is picky about linking against a module library (aka a .so);
giving lots of warnings like this in the tests directory:
CCLD networkxml2argvtest
*** Warning: Linking the executable networkxml2argvtest against the loadable module
*** libvirt_driver_network.so is not portable!
Fix that by splitting things into a convenience library which can
be used directly by the tests, and making the real .so just wrap
the convenience library.
Based on a suggestion by Daniel P. Berrange.
* configure.ac (--with-driver-modules): Fix help test.
* src/Makefile.am (libvirt_driver_xen.la, libvirt_driver_libxl.la)
(libvirt_driver_qemu.la, libvirt_driver_lxc.la)
(libvirt_driver_uml.la): Factor into new convenience libraries.
* tests/Makefile.am (xen_LDADDS, qemu_LDADDS, lxc_LDADDS)
(networkxml2argvtest_LDADD): Link to convenience libraries, not
shared libraries.
Libtool supports linking directly against .o files on some platforms
(such as Linux), which happens to be the only place where we are
actually doing that (for the dtrace-generated probes.o files). However,
it raises a big stink about the non-portability, even though we don't
attempt it on platforms where it would actually fail:
CCLD libvirt_driver_qemu.la
*** Warning: Linking the shared library libvirt_driver_qemu.la against
the non-libtool
*** objects libvirt_qemu_probes.o is not portable!
This shuts libtool up by creating a proper .lo file that matches
what libtool normally expects.
* src/Makefile.am (%_probes.lo): New rule.
(libvirt_probes.stp, libvirt_qemu_probes.stp): Simplify into...
(%_probes.stp): ...shorter rule.
(CLEANFILES): Clean new .lo files.
(libvirt_la_BUILT_LIBADD, libvirt_driver_qemu_la_LIBADD)
(libvirt_lxc_LDADD, virt_aa_helper_LDADD): Link against .lo file.
* tests/Makefile.am (PROBES_O, qemu_LDADDS): Likewise.
With the switch to modules by default, I was getting super long
test output:
TEST: /home/remote/eblake/libvirt/tests/.libs/lt-interfacexml2xmltest
compared to the former:
TEST: interfacexml2xmltest
* tests/testutils.c (virtTestMain): Trim off libtool goop.
To ensure all symbols used by loadable driver modules are
exported in libvirt.so, add a test suite that simply loads
each driver in turn
* tests/Makefile.am, tests/virdrivermoduletest.c: Add
a test case for loading drivers
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
When building as driver modules, it is not possible for the QEMU
driver module to reference the DTrace/SystemTAP probes linked into
the main libvirt.so. Thus we need to move the QEMU probes into a
separate file 'libvirt_qemu_probes.d'. Also rename the existing
file from 'probes.d' to 'libvirt_probes.d' while we're at it
* daemon/Makefile.am, src/internal.h: Include libvirt_probes.h
instead of probes.h
* src/Makefile.am: Add rules for libvirt_qemu_probes.d
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor_json.c,
src/qemu/qemu_monitor_text.c: Include libvirt_qemu_probes.h
* src/libvirt_probes.d: Rename from probes.d
* src/libvirt_qemu_probes.d: QEMU specific probes formerly
in probes.d
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
The libvirt_test.la library was introduced to allow test suites
to reference internal-only symbols. These days, nearly every
symbol we care about is in src/libvirt_private.syms, so there
is no need for libvirt_test.la to continue to exist
* src/Makefile.am: Delete libvirt_test.la & add new .syms files
* src/libvirt_private.syms: Export symbols needed by test suite
* tests/Makefile.am: Link to libvirt_test.la. Ensure LXC tests link
to network_driver.la
* src/libvirt_esx.syms, src/libvirt_openvz.syms: Add exports needed
by test suite
I'm tired of writing:
bool sep = false;
while (...) {
if (sep)
virBufferAddChar(buf, ',');
sep = true;
virBufferAdd(buf, str);
}
This makes it easier, allowing one to write:
while (...)
virBufferAsprintf(buf, "%s,", str);
virBufferTrim(buf, ",", -1);
to trim any remaining comma.
* src/util/buf.h (virBufferTrim): Declare.
* src/util/buf.c (virBufferTrim): New function.
* tests/virbuftest.c (testBufTrim): Test it.
This patch adds support for a new storage backend with RBD support.
RBD is the RADOS Block Device and is part of the Ceph distributed storage
system.
It comes in two flavours: Qemu-RBD and Kernel RBD, this storage backend only
supports Qemu-RBD, thus limiting the use of this storage driver to Qemu only.
To function this backend relies on librbd and librados being present on the
local system.
The backend also supports Cephx authentication for safe authentication with
the Ceph cluster.
For storing credentials it uses the built-in secret mechanism of libvirt.
Signed-off-by: Wido den Hollander <wido@widodh.nl>
This patch adds support for the recent ipset iptables extension
to libvirt's nwfilter subsystem. Ipset allows to maintain 'sets'
of IP addresses, ports and other packet parameters and allows for
faster lookup (in the order of O(1) vs. O(n)) and rule evaluation
to achieve higher throughput than what can be achieved with
individual iptables rules.
On the command line iptables supports ipset using
iptables ... -m set --match-set <ipset name> <flags> -j ...
where 'ipset name' is the name of a previously created ipset and
flags is a comma-separated list of up to 6 flags. Flags use 'src' and 'dst'
for selecting IP addresses, ports etc. from the source or
destination part of a packet. So a concrete example may look like this:
iptables -A INPUT -m set --match-set test src,src -j ACCEPT
Since ipset management is quite complex, the idea was to leave ipset
management outside of libvirt but still allow users to reference an ipset.
The user would have to make sure the ipset is available once the VM is
started so that the iptables rule(s) referencing the ipset can be created.
Using XML to describe an ipset in an nwfilter rule would then look as
follows:
<rule action='accept' direction='in'>
<all ipset='test' ipsetflags='src,src'/>
</rule>
The two parameters on the command line are also the two distinct XML attributes
'ipset' and 'ipsetflags'.
FYI: Here is the man page for ipset:
https://ipset.netfilter.org/ipset.man.html
Regards,
Stefan
Make it obvious why we need Osier's patch in commit 10d9038b
to fix NUMA parsing of an AMD machine with two cores sharing
a socket id.
* tests/nodeinfotest.c (linuxTestCompareFiles): Enhance the test.
* tests/nodeinfodata/linux-nodeinfo-sysfs-test-*-output.txt: Update.
To allow the security drivers to apply different configuration
information per hypervisor, pass the virtualization driver name
into the security manager constructor.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Thanks to this new option we are now able to use modern CPU models (such
as Westmere) defined in external configuration file.
The qemu-1.1{,-device} data files for qemuhelptest are filled in with
qemu-1.1-rc2 output for now. I will update those files with real
qemu-1.1 output once it is released.
The uhci1, uhci2, uhci3 companion controllers for ehci1 must
have a master start port set. Since this value is predictable
we should set it automatically if the app does not supply it
Currently each USB2 companion controller gets put on a separate
PCI slot. Not only is this wasteful of PCI slots, but it is not
in compliance with the spec for USB2 controllers. The master
echi1 and all companion controllers should be in the same slot,
with echi1 in function 7, and uhci1-3 in functions 0-2 respectively.
* src/qemu/qemu_command.c: Special case handling of USB2 controllers
to apply correct pci slot assignment
* tests/qemuxml2argvdata/qemuxml2argv-usb-ich9-ehci-addr.args,
tests/qemuxml2argvdata/qemuxml2argv-usb-ich9-ehci-addr.xml: Expand
test to cover automatic slot assignment
Sometimes it is useful to see the callpath for log messages.
This change enhances the log filter syntax so that stack traces
can be show by setting '1:+NAME' instead of '1:NAME'.
This results in output like:
2012-05-09 14:18:45.136+0000: 13314: debug : virInitialize:414 : register drivers
/home/berrange/src/virt/libvirt/src/.libs/libvirt.so.0(virInitialize+0xd6)[0x7f89188ebe86]
/home/berrange/src/virt/libvirt/tools/.libs/lt-virsh[0x431921]
/lib64/libc.so.6(__libc_start_main+0xf5)[0x3a21e21735]
/home/berrange/src/virt/libvirt/tools/.libs/lt-virsh[0x40a279]
2012-05-09 14:18:45.136+0000: 13314: debug : virRegisterDriver:775 : driver=0x7f8918d02760 name=Test
/home/berrange/src/virt/libvirt/src/.libs/libvirt.so.0(virRegisterDriver+0x6b)[0x7f89188ec717]
/home/berrange/src/virt/libvirt/src/.libs/libvirt.so.0(+0x11b3ad)[0x7f891891e3ad]
/home/berrange/src/virt/libvirt/src/.libs/libvirt.so.0(virInitialize+0xf3)[0x7f89188ebea3]
/home/berrange/src/virt/libvirt/tools/.libs/lt-virsh[0x431921]
/lib64/libc.so.6(__libc_start_main+0xf5)[0x3a21e21735]
/home/berrange/src/virt/libvirt/tools/.libs/lt-virsh[0x40a279]
* docs/logging.html.in: Document new syntax
* configure.ac: Check for execinfo.h
* src/util/logging.c, src/util/logging.h: Add support for
stack traces
* tests/testutils.c: Adapt to API change
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
"Instead of developing one CPU with 12 cores, the Magny Cours is
actually two 6 core “Bulldozer” CPUs combined in to one package"
I.e, each package has two NUMA nodes, and the two numa nodes share
the same core ID set (0-6), which means parsing the cores number
from sysfs doesn't work in this case.
And the wrong CPU number could cause three problems for libvirt:
1) performance lost
A domain without "cpuset" or "placement='auto'" (to drive numad)
specified will be only pinned to part of the CPUs.
2) domain can be started
If a domain uses numad, and the advisory nodeset returned from
numad contains node which exceeds the range of wrong total CPU
number. The domain will fail to start, as the bitmask passed to
sched_setaffinity could be fully filled with zero.
3) wrong CPU number affects lots of stuffs.
E.g. for command "virsh vcpuinfo", "virsh vcpupin", it will always
output with the truncated CPU list.
For more details:
https://www.redhat.com/archives/libvir-list/2012-May/msg00607.html
This patch is to fix the problem by parsing /proc/cpuinfo to get
the value of field "cpu cores", and use it as nodeinfo->cores if
it's greater than the cores number from sysfs.
For pseries guest, the default controller model is
ibmvscsi controller, this controller only can work
on spapr-vio address.
This patch is to assign spapr-vio address type to
ibmvscsi controller and correct vscsi test case.
Signed-off-by: Li Zhang <zhlcindy@linux.vnet.ibm.com>
Test 2 data grabbed from a 2-core 1-node laptop.
Test 3 data grabbed from a 48-cpu AMD Magny Cours box.
* tests/nodeinfodata/linux-nodeinfo-sysfs-test-2*: New test data.
* tests/nodeinfodata/linux-nodeinfo-sysfs-test-3*: Likewise.
* tests/nodeinfotest.c (mymain): Run them.
* cfg.mk
(exclude_file_name_regexp--sc_prohibit_empty_lines_at_EOF): Exempt
new test files.
We had previously weakened our nodeinfotest in order to ignore parsed
node values, because the parse function was mistakenly relying on
host files. A better fix is to avoid using the numactl library, but
to instead parse the same files that numactl would read, all while
allowing the files to be relative to our choice of directory.
* src/nodeinfo.c (CPU_SYS_PATH, NODE_SYS_PATH): Replace with...
(SYSFS_SYSTEM_PATH): ...parent directory.
(linuxNodeInfoCPUPopulate): Check NUMA nodes from requested
directory (by inlining numactl code).
(nodeGetCPUmap, nodeGetMemoryStats): Adjust macro use.
* tests/nodeinfotest.c (linuxTestCompareFiles, linuxTestNodeInfo):
Update test to match.
<vcpu> is not an optional node. The value for its 'placement'
actually always defaults to 'static' in the underlying codes.
(Even no 'cpuset' and 'placement' is specified, the domain
process will be pinned to all the available pCPUs).
Though numad will manage the memory allocation of task dynamically,
it wants management application (libvirt) to pre-set the memory
policy according to the advisory nodeset returned from querying numad,
(just like pre-bind CPU nodeset for domain process), and thus the
performance could benefit much more from it.
This patch introduces new XML tag 'placement', value 'auto' indicates
whether to set the memory policy with the advisory nodeset from numad,
and its value defaults to the value of <vcpu> placement, or 'static'
if 'nodeset' is specified. Example of the new XML tag's usage:
<numatune>
<memory placement='auto' mode='interleave'/>
</numatune>
Just like what current "numatune" does, the 'auto' numa memory policy
setting uses libnuma's API too.
If <vcpu> "placement" is "auto", and <numatune> is not specified
explicitly, a default <numatume> will be added with "placement"
set as "auto", and "mode" set as "strict".
The following XML can now fully drive numad:
1) <vcpu> placement is 'auto', no <numatune> is specified.
<vcpu placement='auto'>10</vcpu>
2) <vcpu> placement is 'auto', no 'placement' is specified for
<numatune>.
<vcpu placement='auto'>10</vcpu>
<numatune>
<memory mode='interleave'/>
</numatune>
And it's also able to control the CPU placement and memory policy
independently. e.g.
1) <vcpu> placement is 'auto', and <numatune> placement is 'static'
<vcpu placement='auto'>10</vcpu>
<numatune>
<memory mode='strict' nodeset='0-10,^7'/>
</numatune>
2) <vcpu> placement is 'static', and <numatune> placement is 'auto'
<vcpu placement='static' cpuset='0-24,^12'>10</vcpu>
<numatune>
<memory mode='interleave' placement='auto'/>
</numatume>
A follow up patch will change the XML formatting codes to always output
'placement' for <vcpu>, even it's 'static'.
Alon tried './qemuxml2argvtest --help' to figure out a test failure,
but it didn't help. The information is in HACKING, but it doesn't
hurt to make the tests also provide their own help.
Signed-off-by: Alon Levy <alevy@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
qemu's behavior in this case is to change the spice server behavior to
require secure connection to any channel not otherwise specified as
being in plaintext mode. libvirt doesn't currently allow requesting this
(via plaintext-channel=<channel name>).
RHBZ: 819499
Signed-off-by: Alon Levy <alevy@redhat.com>
We only know -lpthread exists on platforms where we build
threads-pthread.c; but when we build threads-win32.c, LIB_PTHREAD
is empty.
* tests/Makefile.am (shunloadtest_LDADD): Use correct library.
Error: RESOURCE_LEAK:
/libvirt/tests/qemuxml2argvtest.c:47:
alloc_arg: Calling allocation function "virAlloc" on "ret".
/libvirt/src/util/memory.c:101:
alloc_fn: Storage is returned from allocation function "calloc".
/libvirt/src/util/memory.c:101:
var_assign: Assigning: "*((void **)ptrptr)" = "calloc(1UL, size)".
/libvirt/tests/qemuxml2argvtest.c:54:
leaked_storage: Variable "ret" going out of scope leaks the storage it points to.
On cygwin, <rpc/rpc.h> lives in a different directory than
/usr/include, so anything that uses it must modify CFLAGS. This
previously tripped up just 'make check', but now that we build
all test programs unconditionally, it also trips up 'make'.
* tests/Makefile.am (virnetmessagetest_CFLAGS): Find rpc headers.
The recent push to use correct scaling terms (kB for 1000, KiB for
1024 - such as commit 9dfdead) missed some places in virsh.
* tools/virsh.c (prettyCapacity, cmdDominfo, cmdFreecell)
(cmdNodeinfo, cmdNodeMemStats, cmdMigrateSetMaxSpeed)
(cmdBlockCopy, cmdBlockPull, cmdBlockJob): Use KiB, not kB, when
referring to multiples of 1024.
* tests/virshtest.c: Update expected output to match.
This works with newer qemu that doesn't allow escaping spaces.
It's backwards compatible as well.
Signed-off-by: Josh Durgin <josh.durgin@dreamhost.com>
More bug extermination in the category of:
Error: CHECKED_RETURN:
/libvirt/src/conf/network_conf.c:595:
check_return: Calling function "virAsprintf" without checking return value (as is done elsewhere 515 out of 543 times).
/libvirt/src/qemu/qemu_process.c:2780:
unchecked_value: No check of the return value of "virAsprintf(&msg, "was paused (%s)", virDomainPausedReasonTypeToString(reason))".
/libvirt/tests/commandtest.c:809:
check_return: Calling function "setsid" without checking return value (as is done elsewhere 4 out of 5 times).
/libvirt/tests/commandtest.c:830:
unchecked_value: No check of the return value of "virTestGetDebug()".
/libvirt/tests/commandtest.c:831:
check_return: Calling function "virTestGetVerbose" without checking return value (as is done elsewhere 41 out of 42 times).
/libvirt/tests/commandtest.c:833:
check_return: Calling function "virInitialize" without checking return value (as is done elsewhere 18 out of 21 times).
One note about the error in commandtest line 809: setsid() seems to fail when running the test -- could be removed ?
In order to track a block copy job across libvirtd restarts, we
need to save internal XML that tracks the name of the file
holding the mirror. Displaying this name in dumpxml might also
be useful to the user, even if we don't yet have a way to (re-)
start a domain with mirroring enabled up front. This is done
with a new <mirror> sub-element to <disk>, as in:
<disk type='file' device='disk'>
<driver name='qemu' type='raw'/>
<source file='/var/lib/libvirt/images/original.img'/>
<mirror file='/var/lib/libvirt/images/copy.img' format='qcow2' ready='yes'/>
...
</disk>
For now, the element is output-only, in live domains; it is ignored
when defining a domain or hot-plugging a disk (since those contexts
use VIR_DOMAIN_XML_INACTIVE in parsing). The 'ready' attribute appears
when libvirt knows that the job has changed from the initial pulling
phase over to the mirroring phase, although absence of the attribute
is not a sure indicator of the current phase. If we come up with a way
to make qemu start with mirroring enabled, we can relax the xml
restriction, and allow <mirror> (but not attribute 'ready') on input.
Testing active-only XML meant tweaking the testsuite slightly, but it
was worth it.
* docs/schemas/domaincommon.rng (diskspec): Add diskMirror.
* docs/formatdomain.html.in (elementsDisks): Document it.
* src/conf/domain_conf.h (_virDomainDiskDef): New members.
* src/conf/domain_conf.c (virDomainDiskDefFree): Clean them.
(virDomainDiskDefParseXML): Parse them, but only internally.
(virDomainDiskDefFormat): Output them.
* tests/qemuxml2argvdata/qemuxml2argv-disk-mirror.xml: New test file.
* tests/qemuxml2xmloutdata/qemuxml2xmlout-disk-mirror.xml: Likewise.
* tests/qemuxml2xmltest.c (testInfo): Alter members.
(testCompareXMLToXMLHelper): Allow more test control.
(mymain): Run new test.
This patch modifies the CPU comparrison function to report the
incompatibilities in more detail to ease identification of problems.
* src/cpu/cpu.h:
cpuGuestData(): Add argument to return detailed error message.
* src/cpu/cpu.c:
cpuGuestData(): Add passthrough for error argument.
* src/cpu/cpu_x86.c
x86FeatureNames(): Add function to convert a CPU definition to flag
names.
x86Compute(): - Add error message parameter
- Add macro for reporting detailed error messages.
- Improve error reporting.
- Simplify calculation of forbidden flags.
x86DataIteratorInit():
x86cpuidMatchAny(): Remove functions that are no longer needed.
* src/qemu/qemu_command.c:
qemuBuildCpuArgStr(): - Modify for new function prototype
- Add detailed error reports
- Change error code on incompatible processors
to VIR_ERR_CONFIG_UNSUPPORTED instead of
internal error
* tests/cputest.c:
cpuTestGuestData(): Modify for new function prototype
Since now we have fixed domain UUID for test driver, defining
a domain with different name but same UUID doesn't work any
more. This patch delete the UUID from the dumped XML so that
it could be generated.
A "ide-drive" device can be either a hard disk or a CD-ROM,
if there is ",media=cdrom" specified for the backend, it's
a CD-ROM, otherwise it's a hard disk.
Upstream qemu splitted "ide-drive" into "ide-hd" and "ide-cd"
since commit 1f56e32, and ",media=cdrom" is not required for
ide-cd anymore. "ide-drive" is still supported for backwards
compatibility, but no doubt we should go foward.
A "scsi-disk" device can be either a hard disk or a CD-ROM,
if there is ",media=cdrom" specified for the backend, it's
a CD-ROM, otherwise it's a hard disk.
But upstream qemu splitted "scsi-disk" into "scsi-hd" and
"scsi-cd" since commit b443ae, and ",media=cdrom" is not
required for scsi-cd anymore. "scsi-disk" is still supported
for backwards compatibility, but no doubt we should go
foward.
* src/qemu/qemu_command.c: Wire up -bios with <loader>
* tests/qemuxml2argvdata/qemuxml2argv-bios.args,
tests/qemuxml2argvdata/qemuxml2argv-bios.xml: Expand
existing BIOS test case to cover <loader>
