[libvirt PATCH 0/9] [RFC] Dynamic CPU models

[Tim Wiederhake]

libvirt and qemu cpu models are out of sync. libvirt cpu models are
considered static and never changing, whereas qemu cpu models have
changed over time. This leads to problems and confusion for users,
as the cpu models they specify may have different features than what
they expect.

This series introduces two new APIs to enumerate and retrieve cpu
models dynamically from the hypervisor at runtime, allowing the user
to make use of cpu models from newer hypervisor versions even if
libvirt is not aware of them.

These two new functions are intended as building blocks onto which
higher-level functionality can be build, e.g. the ability to specify
a hypervisor cpu model directly in a domain xml. With these two
functions alone this has to be done manually for now, i.e. enumerate
the available cpu models, retrieve the cpu description and manually
insert it into the domain xml accordingly:

    $ virsh hypervisor-cpu-models --arch x86_64
    Name                        Alias
    ----------------------------------------------------
    max
    host
    base
    qemu64-v1
    qemu64                      qemu64-v1
    qemu32-v1
    qemu32                      qemu32-v1
    phenom-v1
    phenom                      phenom-v1
    (...)

    $ virsh hypervisor-cpu-definition --machine pc --arch x86_64 qemu64
    <cpu>
      <model>qemu64</model>
      <feature name='cmov'/>
      <feature name='mmx'/>
      <feature name='xd'/>
      <feature name='x-intel-pt-auto-level'/>
      <feature name='kvm_asyncpf'/>
      <feature name='kvm-asyncpf'/>
      <feature name='legacy-cache'/>
      <feature name='vmware-cpuid-freq'/>
      <feature name='mce'/>
      <feature name='mca'/>
      <feature name='msr'/>
      <feature name='fxsr'/>
      <feature name='cpuid-0xb'/>
      <feature name='kvm_pv_eoi'/>
      <feature name='pni'/>
      <feature name='x2apic'/>
      <feature name='i64'/>
      <feature name='pae'/>
      <feature name='pat'/>
      <feature name='sse'/>
      <feature name='kvm_nopiodelay'/>
      <feature name='kvm-nopiodelay'/>
      <feature name='kvmclock-stable-bit'/>
      <feature name='hypervisor'/>
      <feature name='syscall'/>
      <feature name='x-migrate-smi-count'/>
      <feature name='full-cpuid-auto-level'/>
      <feature name='sse3'/>
      <feature name='sse2'/>
      <feature name='kvm-pv-eoi'/>
      <feature name='cx8'/>
      <feature name='pge'/>
      <feature name='fill-mtrr-mask'/>
      <feature name='cx16'/>
      <feature name='de'/>
      <feature name='clflush'/>
      <feature name='tsc'/>
      <feature name='fpu'/>
      <feature name='check'/>
      <feature name='apic'/>
      <feature name='kvm-steal-time'/>
      <feature name='kvm_steal_time'/>
      <feature name='kvmclock'/>
      <feature name='l3-cache'/>
      <feature name='nx'/>
      <feature name='tcg-cpuid'/>
      <feature name='lm'/>
      <feature name='pse'/>
      <feature name='sep'/>
      <feature name='kvm'/>
      <feature name='lahf-lm'/>
      <feature name='lahf_lm'/>
      <feature name='mtrr'/>
      <feature name='pse36'/>
    </cpu>

The returned cpu description is currently completely unfiltered, as
can be seen by the duplicate entries differing only in "-" vs. "_"
usage, inclusion of experimental feature flags and generally, flags
that are not recognized by libvirt. One possibility to adress this
would be to extend virQEMUCapsCPUFeatureTranslate.

Before I continue with this, I would love to hear other people's
thoughts, comments and potential use cases.

Cheers,
Tim

Tim Wiederhake (9):
  qemuMonitorCPUDefInfo: Add alias
  libvirt: introduce virConnectGetHypervisorCPUModelNames public API
  remote: Add RPC support for the virConnectGetHypervisorCPUModelNames
    API
  qemu: implement virConnectGetHypervisorCPUModelNames API
  tools: Report hypervisor cpu model names
  libvirt: introduce virConnectGetHypervisorCPUModelDefinition public
    API
  remote: Add support for the virConnectGetHypervisorCPUModelDefinition
    API
  qemu: Implement virConnectGetHypervisorCPUModelDefinition API
  tools: Report hypervisor cpu model definitions

 docs/manpages/virsh.rst             |  27 ++++++
 include/libvirt/libvirt-host.h      |  13 +++
 src/driver-hypervisor.h             |  17 ++++
 src/libvirt-host.c                  | 109 +++++++++++++++++++++++
 src/libvirt_public.syms             |   2 +
 src/qemu/qemu_driver.c              | 105 ++++++++++++++++++++++
 src/qemu/qemu_monitor.c             |   2 +
 src/qemu/qemu_monitor.h             |   1 +
 src/qemu/qemu_monitor_json.c        |   3 +
 src/remote/remote_daemon_dispatch.c |  76 ++++++++++++++++
 src/remote/remote_driver.c          | 100 +++++++++++++++++++++
 src/remote/remote_protocol.x        |  37 +++++++-
 src/remote_protocol-structs         |  27 ++++++
 tools/virsh-host.c                  | 132 ++++++++++++++++++++++++++++
 14 files changed, 650 insertions(+), 1 deletion(-)

-- 
2.31.1