This is in response to:
https://bugzilla.redhat.com/show_bug.cgi?id=629662
Explanation
qemu's virtio-net-pci driver allows setting the algorithm used for tx
packets to either "bh" or "timer". This is done by adding ",tx=bh" or
",tx=timer" to the "-device virtio-net-pci" commandline option.
'bh' stands for 'bottom half'; when this is set, packet tx is all done
in an iothread in the bottom half of the driver. (In libvirt, this
option is called the more descriptive "iothread".)
'timer' means that tx work is done in qemu, and if there is more tx
data than can be sent at the present time, a timer is set before qemu
moves on to do other things; when the timer fires, another attempt is
made to send more data. (libvirt retains the name "timer" for this
option.)
The resulting difference, according to the qemu developer who added
the option is:
bh makes tx more asynchronous and reduces latency, but potentially
causes more processor bandwidth contention since the cpu doing the
tx isn't necessarily the cpu where the guest generated the
packets.
Solution
This patch provides a libvirt domain xml knob to change the option on
the qemu commandline, by adding a new attribute "txmode" to the
<driver> element that can be placed inside any <interface> element in
a domain definition. It's use would be something like this:
<interface ...>
...
<model type='virtio'/>
<driver txmode='iothread'/>
...
</interface>
I chose to put this setting as an attribute to <driver> rather than as
a sub-element to <tune> because it is specific to the virtio-net
driver, not something that is generally usable by all network drivers.
(note that this is the same placement as the "driver name=..."
attribute used to choose kernel vs. userland backend for the
virtio-net driver.)
Actually adding the tx=xxx option to the qemu commandline is only done
if the version of qemu being used advertises it in the output of
qemu -device virtio-net-pci,?
If a particular txmode is requested in the XML, and the option isn't
listed in that help output, an UNSUPPORTED_CONFIG error is logged, and
the domain fails to start.
qemu 0.13.0 (at least as built for Fedora 14, and also backported to
RHEL 6.0 qemu) supported an older syntax for a spicevmc channel; it's
not as flexible (it has an implicit name and hides the chardev
aspect), but now that we support spicevmc, we might as well target
both variants.
* src/qemu/qemu_capabilities.h (QEMUD_CMD_FLAG_DEVICE_SPICEVMC):
New flag.
* src/qemu/qemu_capabilities.c (qemuCapsParseDeviceStr): Set it
correctly.
* src/qemu/qemu_command.h (qemuBuildVirtioSerialPortDevStr): Drop
declaration.
* src/qemu/qemu_command.c (qemuBuildVirtioSerialPortDevStr): Alter
signature, check flag.
(qemuBuildCommandLine): Adjust caller and check flag.
* tests/qemuhelptest.c (mymain): Update test.
* tests/qemuxml2argvtest.c (mymain): New test.
* tests/qemuxml2argvdata/qemuxml2argv-channel-spicevmc-old.xml:
New file.
* tests/qemuxml2argvdata/qemuxml2argv-channel-spicevmc-old.args:
Likewise.
Qemu smartcard/spicevmc support exists on branches (such as
http://cgit.freedesktop.org/~alon/qemu/commit/?h=usb_ccid.v15&id=024a37b)
but is not yet upstream. The added -help output matches a scratch build
that will be close to the RHEL 6.1 qemu-kvm.
* src/qemu/qemu_capabilities.h (QEMUD_CMD_FLAG_CCID_EMULATED)
(QEMUD_CMD_FLAG_CCID_PASSTHRU, QEMUD_CMD_FLAG_CHARDEV_SPICEVMC):
New flags.
* src/qemu/qemu_capabilities.c (qemuCapsComputeCmdFlags)
(qemuCapsParseDeviceStr): Check for smartcard capabilities.
(qemuCapsExtractVersionInfo): Tweak comment.
* tests/qemuhelptest.c (mymain): New test.
* tests/qemuhelpdata/qemu-kvm-0.12.1.2-rhel61: New file.
* tests/qemuhelpdata/qemu-kvm-0.12.1.2-rhel61-device: Likewise.
* src/qemu/qemu_capabilities.h (qemuCapsParseDeviceStr): New
prototype.
* src/qemu/qemu_capabilities.c (qemuCapsParsePCIDeviceStrs)
Rename and split...
(qemuCapsExtractDeviceStr, qemuCapsParseDeviceStr): ...to make it
easier to add and test device-specific checks.
(qemuCapsExtractVersionInfo): Update caller.
* tests/qemuhelptest.c (testHelpStrParsing): Also test parsing of
device-related flags.
(mymain): Update expected flags.
* tests/qemuhelpdata/qemu-0.12.1-device: New file.
* tests/qemuhelpdata/qemu-kvm-0.12.1.2-rhel60-device: New file.
* tests/qemuhelpdata/qemu-kvm-0.12.3-device: New file.
* tests/qemuhelpdata/qemu-kvm-0.13.0-device: New file.
* tests/qemuhelpdata/qemu-kvm-0.13.0: New file.
* tests/qemuhelptest.c (mymain): New test from Fedora 14 qemu-kvm,
which covers some options (like -fstype passthrough) not tested elsewhere.
* tests/qemuhelpdata/qemu-kvm-0.12.1.2-rhel60: New file.
* tests/qemuhelptest.c (mymain): New test from RHEL 6.0 qemu-kvm,
which covers some options (like -vga=qxl) not tested elsewhere.
* .x-sc_prohibit_empty_lines_at_EOF: Exempt qemu help output.
Commit febc591683 introduced -vga none in
case no video card is included in domain XML. However, old qemu
versions do not support this and such domain cannot be successfully
started.
* docs/schemas/domain.rng: Fix merge error which left SPICE channel
elements under VNC schema.
* tests/qemuhelptest.c: Add SPICE flag to kvm-83 test
* tests/qemuxml2argvdata/qemuxml2argv-graphics-spice.xml: Add
<memballoon> element
The patch is based on the possiblity in the QEmu command line to
add -smbios options allowing to override the default values picked
by QEmu. We need to detect this first from QEmu help output.
If the domain is defined with smbios to be inherited from host
then we pass the values coming from the Host own SMBIOS, but
if the domain is defined with smbios to come from sysinfo, we
use the ones coming from the domain definition.
* src/qemu/qemu_conf.h: add the QEMUD_CMD_FLAG_SMBIOS_TYPE enum
value
* src/qemu/qemu_conf.c: scan the help output for the smbios support,
and if available add support based on the domain definitions,
and host data
* tests/qemuhelptest.c: add the new enum in the outputs
So far, readonly=on option is used when qemu supports -device. However,
there are qemu versions which support readonly option with -drive
although they don't have support for -device.
This sets the process name to the same value as the Windows title,
but since the name is limited to 16 chars only this is kept as a
configuration option and turned off by default
* src/qemu/qemu.conf src/qemu/qemu_conf.[ch]: hceck for support in the
QEmu help output, add the option in qemu conf file and augment
qemudBuildCommandLine to add it if switched on
* src/qemu/libvirtd_qemu.aug src/qemu/test_libvirtd_qemu.aug: augment
the augeas lenses accordingly
* tests/qemuhelptest.c: cope with the extra flag being detected now
This enables support for nested SVM using the regular CPU
model/features block. If the CPU model or features include
'svm', then the '-enable-nesting' flag will be added to the
QEMU command line. Latest out of tree patches for nested
'vmx', no longer require the '-enable-nesting' flag. They
instead just look at the cpu features. Several of the models
already include svm support, but QEMU was just masking out
the svm bit silently. So this will enable SVM on such
models
* src/qemu/qemu_conf.h: flag for -enable-nesting
* src/qemu/qemu_conf.c: Use -enable-nesting if VMX or SVM are in
the CPUID
* src/cpu/cpu.h, src/cpu/cpu.c: API to check for a named feature
* src/cpu/cpu_x86.c: x86 impl of feature check
* src/libvirt_private.syms: Add cpuHasFeature
* src/qemuhelptest.c: Add nesting flag where required
Add a new element to the <os> block:
<bootmenu enable="yes|no"/>
Which maps to -boot,menu=on|off on the QEMU command line.
I decided to use an explicit 'enable' attribute rather than just make the
bootmenu element boolean. This allows us to treat lack of a bootmenu element
as 'use hypervisor default'.
(gdb) p/x QEMUD_CMD_FLAG_VNET_HOST
$7 = 0xffffffff80000000
Oops - that meant we were incorrectly setting QEMU_CMD_FLAG_RTC_TD_HACK
for qemu-kvm-0.12.3 (and probably botching a few other settings as well).
Fixes Red Hat BZ#592070
* src/qemu/qemu_conf.h (QEMUD_CMD_FLAG_VNET_HOST): Avoid sign
extension.
* tests/qemuhelpdata/qemu-kvm-0.12.3: New file.
* tests/qemuhelptest.c (mymain): Add another case.
* src/qemu/qemu_conf.h: define 4 new flags
* src/qemu/qemu_conf.c: check the help text of qemu for presence of
features indicated by each flag.
* tests/qemuhelptest.c: add appropriate flags into the masks for each test
This allows QEMU guests to be started with an arbitrary clock
offset
The test case can't actually be enabled, since QEMU argv expects
an absolute timestring, and this will obviously change every
time the test runs :-( Hopefully QEMU will allow a relative
time offset in the future.
* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h: Use the -rtc arg
if available to support variable clock offset mode
* tests/qemuhelptest.c: Add QEMUD_CMD_FLAG_RTC for qemu 0.12.1
* qemuxml2argvdata/qemuxml2argv-clock-variable.args,
qemuxml2argvdata/qemuxml2argv-clock-variable.xml,
qemuxml2argvtest.c: Test case, except we can't actually enable
it yet.
The QEMU flags are commonly stored as a signed or unsigned int,
allowing only 31 flags. This limit is rather close, so to aid
future patches, change it to a 64-bit int
* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h, src/qemu/qemu_driver.c,
tests/qemuargv2xmltest.c, tests/qemuhelptest.c, tests/qemuxml2argvtest.c:
Use 'unsigned long long' for QEMU flags
QEMU's command line equivalent for the following domain XML fragment
<vcpus>2</vcpus>
<cpu ...>
...
<topology sockets='1' cores='2', threads='1'/>
</cpu>
is
-smp 2,sockets=1,cores=2,threads=1
This syntax was introduced in QEMU-0.12.
Version 2 changes:
- -smp argument build split into a separate function
- always add ",sockets=S,cores=C,threads=T" to -smp if qemu supports it
- use qemuParseCommandLineKeywords for command line parsing
Version 3 changes:
- ADD_ARG_LIT => ADD_ARG and line reordering in qemudBuildCommandLine
- rebased
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Not all QEMU builds default to SDL graphics for their display.
Newer QEMU now has an explicit -sdl flag, which we can use to
explicitly request SDL intead of relying on the default. This
protects libvirt against unexpected changes in graphics default
* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h: Probe for -sdl
flag and use it if it is found
* tests/qemuhelptest.c: Add SDL flag to tests
Probe for the new -device flag and if available set the -nodefaults
flag, instead of using -net none, -serial none or -parallel none.
Other device types will be converted to use -device in later patches.
The -nodefaults flag will help avoid unwelcome surprises from future
QEMU releases
* src/qemu/qemu_conf.c: Probe for -device. Add -nodefaults flag.
Remove -net none, -serial none or -parallel none
* src/qemu/qemu_conf.h: Define QEMU_CMD_FLAG_DEVICE
* tests/qemuhelpdata/qemu-0.12.1: New data file for 0.12.1 QEMU
* tests/qemuhelptest.c: Test feature extraction from 0.12.1 QEMU
The behavior for the qemu balloon device has changed. Formerly, a virtio
balloon device was provided by default. Now, '-balloon virtio' must be
specified on the command line to enable it. This patch causes libvirt to
add '-balloon virtio' to the command line whenever the -balloon option is
available.
* src/qemu/qemu_conf.c src/qemu/qemu_conf.h: check for the new flag and
add "-baloon vitio" to qemu command when needed
* tests/qemuhelptest.c: add the new flag for detection
Recent qemu releases require command option '-enable-qemu' in order
for the kvm functionality be activated. Libvirt needs to pass this flag
to qemu when starting a domain. Note that without the option,
even if both the kernel and qemu support KVM, KVM will not be activated
and VMs will be very slow.
* src/qemu/qemu_conf.h src/qemu/qemu_conf.c: parse the extra command
line option from help and add it when running kvm
* tests/qemuhelptest.c: this modified the flags output for qemu-0.10.5
and qemu-kvm-0.11.0-rc2 regression tests
* docs/schemas/domain.rng: Add <serial> element to disks
* src/domain_conf.h, src/domain_conf.c: XML parsing and
formatting for disk serial numbers
* src/qemu_conf.c: Set serial number when launching guests
* tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.args,
tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.xml: Add
serial number to XML test
Add option to domain XML for
<memoryBacking>
<hugepages/>
</memoryBacking>
* configure.in: Add check for mntent.h
* qemud/libvirtd_qemu.aug, qemud/test_libvirtd_qemu.aug, src/qemu.conf
Add 'hugetlbfs_mount' config parameter
* src/qemu_conf.c, src/qemu_conf.h: Check for -mem-path flag in QEMU,
and pass it when hugepages are requested.
Load hugetlbfs_mount config parameter, search for mount if not given.
* src/qemu_driver.c: Free hugetlbfs_mount/path parameter in driver shutdown.
Create directory for QEMU hugepage usage, chowning if required.
* docs/formatdomain.html.in: Document memoryBacking/hugepages elements
* docs/schemas/domain.rng: Add memoryBacking/hugepages elements to schema
* src/util.c, src/util.h, src/libvirt_private.syms: Add virFileFindMountPoint
helper API
* tests/qemuhelptest.c: Add -mem-path constants
* tests/qemuxml2argvtest.c, tests/qemuxml2xmltest.c: Add tests for hugepage
handling
* tests/qemuxml2argvdata/qemuxml2argv-hugepages.xml,
tests/qemuxml2argvdata/qemuxml2argv-hugepages.args: Data files for
hugepage tests
PCI device assignment is only supported in KVM's fork of qemu, so we
should really detect its availability and give a nice error if its
not supported.
* src/qemu_conf.[ch]: introduce QEMUD_CMD_FLAG_PCIDEVICE indicating
that the -pcidevice command line option is available
* tests/*: update the tests
Add QEMUD_CMD_FLAG_NET_NAME to indicate that '-net ...,name=foo' is
supported and QEMUD_CMD_FLAG_HOST_NET_ADD to indicate that the
'host_net_add' monitor command is available.
Set both these flags if the qemu version is greater than 0.10.0.
Checking via the '-help' output would not work for the monitor command
and even for the command line arg, it would be quite fragile.
* src/qemu_conf.h: add new flags as aliases of QEMUD_CMD_FLAG_0_10
* src/qemu_conf.c: set QEMUD_CMD_FLAG_0_10 for versions >= 0.10.0
* tests/qemuhelptest.c: set QEMUD_CMD_FLAG_0_10 for the appropriate
qemu versions
* src/qemu_conf.c, src/qemu_conf.h: Use -vga or -std-vga
when starting guests if video card is present
* tests/qemuhelptest.c: Change to use constants instead
of hardcoded hex numbers, and add VGA support
* tests/qemuxml2argvdata/qemuxml2argv-graphics-sdl-fullscreen.xml,
tests/qemuxml2argvdata/qemuxml2argv-graphics-sdl.args,
tests/qemuxml2argvdata/qemuxml2argv-graphics-sdl.xml,
tests/qemuxml2argvdata/qemuxml2argv-graphics-vnc-sasl.args,
tests/qemuxml2argvdata/qemuxml2argv-graphics-vnc-sasl.xml,
tests/qemuxml2argvdata/qemuxml2argv-graphics-vnc-tls.xml,
tests/qemuxml2argvdata/qemuxml2argv-graphics-vnc.xml,
tests/qemuxml2argvdata/qemuxml2argv-input-xen.xml: Add <video>
element for testing graphics adapter
* tests/qemuxml2argvtest.c: Add QEMUD_CMD_FLAG_VGA flag
* tests/qemuxml2xmltest.c: Add missing graphics-vnc-sasl/tls tests
