Each driver supporting CPU selection must fill in host CPU capabilities.
When filling them, drivers for hypervisors running on the same node as
libvirtd can use cpuNodeData() to obtain raw CPU data. Other drivers,
such as VMware, need to implement their own way of getting such data.
Raw data can be decoded into virCPUDefPtr using cpuDecode() function.
When implementing virConnectCompareCPU(), a hypervisor driver can just
call cpuCompareXML() function with host CPU capabilities.
For each guest for which a driver supports selecting CPU models, it must
set the appropriate feature in guest's capabilities:
virCapabilitiesAddGuestFeature(guest, "cpuselection", 1, 0)
Actions needed when a domain is being created depend on whether the
hypervisor understands raw CPU data (currently CPUID for i686, x86_64
architectures) or symbolic names has to be used.
Typical use by hypervisors which prefer CPUID (such as VMware and Xen):
- convert guest CPU configuration from domain's XML into a set of raw
data structures each representing one of the feature policies:
cpuEncode(conn, architecture, guest_cpu_config,
&forced_data, &required_data, &optional_data,
&disabled_data, &forbidden_data)
- create a mask or whatever the hypervisor expects to see and pass it
to the hypervisor
Typical use by hypervisors with symbolic model names (such as QEMU):
- get raw CPU data for a computed guest CPU:
cpuGuestData(conn, host_cpu, guest_cpu_config, &data)
- decode raw data into virCPUDefPtr with a possible restriction on
allowed model names:
cpuDecode(conn, guest, data, n_allowed_models, allowed_models)
- pass guest->model and guest->features to the hypervisor
* src/cpu/cpu.c src/cpu/cpu.h src/cpu/cpu_generic.c
src/cpu/cpu_generic.h src/cpu/cpu_map.c src/cpu/cpu_map.h
src/cpu/cpu_x86.c src/cpu/cpu_x86.h src/cpu/cpu_x86_data.h
* configure.in: check for CPUID instruction
* src/Makefile.am: glue the new files in
* src/libvirt_private.syms: add new private symbols
* po/POTFILES.in: add new cpu files containing translatable strings
* src/remote/remote_protocol.x: update with new entry point
* daemon/remote.c: add the new server dispatcher
* daemon/remote_dispatch_args.h daemon/remote_dispatch_prototypes.h
daemon/remote_dispatch_ret.h daemon/remote_dispatch_table.h
src/remote/remote_protocol.c src/remote/remote_protocol.h: regenerated
* src/driver.h: add an extra entry point in the structure
* src/esx/esx_driver.c src/lxc/lxc_driver.c src/opennebula/one_driver.c
src/openvz/openvz_driver.c src/phyp/phyp_driver.c src/qemu/qemu_driver.c
src/remote/remote_driver.c src/test/test_driver.c src/uml/uml_driver.c
src/vbox/vbox_tmpl.c src/xen/xen_driver.c: add NULL entry points for
all drivers
* include/libvirt/virterror.h src/util/virterror.c: add new domain
VIR_FROM_CPU for errors
* src/conf/cpu_conf.c src/conf/cpu_conf.h: new parsing module
* src/Makefile.am proxy/Makefile.am: include new files
* src/conf/capabilities.[ch] src/conf/domain_conf.[ch]: reference
new code
* src/libvirt_private.syms: private export of new entry points
XML schema for CPU flags
Firstly, CPU topology and model with optional features have to be
advertised in host capabilities:
<host>
<cpu>
<arch>ARCHITECTURE</arch>
<features>
<!-- old-style features are here -->
</features>
<model>NAME</model>
<topology sockets="S" cores="C" threads="T"/>
<feature name="NAME"/>
</cpu>
...
</host>
Secondly, drivers which support detailed CPU specification have to
advertise
it in guest capabilities:
<guest>
...
<features>
<cpuselection/>
</features>
</guest>
And finally, CPU may be configured in domain XML configuration:
<domain>
...
<cpu match="MATCH">
<model>NAME</model>
<topology sockets="S" cores="C" threads="T"/>
<feature policy="POLICY" name="NAME"/>
</cpu>
</domain>
Where MATCH can be one of:
- 'minimum' specified CPU is the minimum requested CPU
- 'exact' disable all additional features provided by host CPU
- 'strict' fail if host CPU doesn't exactly match
POLICY can be one of:
- 'force' turn on the feature, even if host doesn't have it
- 'require' fail if host doesn't have the feature
- 'optional' match host
- 'disable' turn off the feature, even if host has it
- 'forbid' fail if host has the feature
'force' and 'disable' policies turn on/off the feature regardless of its
availability on host. 'force' is unlikely to be used but its there for
completeness since Xen and VMWare allow it.
'require' and 'forbid' policies prevent a guest from being started on a host
which doesn't/does have the feature. 'forbid' is for cases where you disable
the feature but a guest may still try to access it anyway and you don't want
it to succeed.
'optional' policy sets the feature according to its availability on host.
When a guest is booted on a host that has the feature and then migrated to
another host, the policy changes to 'require' as we can't take the feature
away from a running guest.
Default policy for features provided by host CPU but not specified in domain
configuration is set using match attribute of cpu tag. If 'minimum' match is
requested, additional features will be treated as if they were specified
with 'optional' policy. 'exact' match implies 'disable' policy and 'strict'
match stands for 'forbid' policy.
* docs/schemas/capability.rng docs/schemas/domain.rng: extend the
RelaxNG schemas to add CPU flags support
src/node_device/node_device_udev.c was using a function available only
on the daemon code, fix this and use the function available globally
* src/node_device/node_device_udev.c: replace use of virEventAddHandleImpl
by virEventAddHandle
Some of the very useful calls for XML parsing provided by util/xml.[ch]
were not exported as private symbols. This patch fixes this.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Xen HVM guests with PV drivers end up with two network interfaces for
each configured interface. One of them being emulated by qemu and the
other one paravirtual. As this might not be desirable, the attached
patch provides a way for users to specify that only paravirtual network
interface should be presented to the guest.
The configuration was inspired by qemu/kvm driver, for which users can
specify model='virtio' to use paravirtual network interface.
The patch adds support for model='netfront' which results in
type=netfront instead of type=ioemu (or nothing for newer xen versions)
in guests native configuration. Xen's qemu ignores interfaces with
type != ioemu and only paravirtual network device will be seen in the
guest.
Four possible configuration scenarios follow:
- no model specified in domain's XML
- libvirt will behave like before this change; it will set
type=ioemu for HVM guests on xen host which is not newer than
XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU
- covered by existing tests
- PV guest, any model
- no functional change, model is passed as is (and ignored by the
hypervisor)
- covered by existing tests (e.g., *-net-e1000.*)
- HVM guest, model=netfront
- type is set to "netfront", model is not specified
- covered by new *-net-netfront.* tests
- HVM guest, model != netfront
- type is set to "ioemu", model is passed as is
- covered by new *-net-ioemu.* tests
The fourth scenario feels like a regression for xen newer than
XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU as users who had a model specified
in their guest's configuration won't see a paravirtual interface in
their guests any more. On the other hand, the reason for specifying a
model is most likely the fact that they want to use such model which
implies emulated interface. Users of older xen won't be affected at all
as their xen provides paravirtual interface regardless of the type used.
- src/xen/xend_internal.c: add netfront support for the xend backend
- src/xen/xm_internal.c: add netfront support for the XM serialization too
* cfg.mk: use $(srcdir)/ prefix for Makefile.nonreentrant include
* examples/domain-events/events-c/Makefile.am tools/Makefile.am
examples/hellolibvirt/Makefile.am: extend the include paths to
use $(top_srcdir)/include too.
Jiri Denemark