Re: [libvirt] [Qemu-devel] [PATCH 1/3] qmp: Add query-host-cpu command

On 06/20/2016 02:12 PM, Eduardo Habkost wrote: > The command can be used to return host-specific CPU capabilities > information. > > Signed-off-by: Eduardo Habkost <ehabkost(a)redhat.com&gt; > --- > include/sysemu/arch_init.h | 1 + > qapi-schema.json | 36 ++++++++++++++++++++++++++++++++++++ > qmp-commands.hx | 6 ++++++ > qmp.c | 13 +++++++++++++ > stubs/Makefile.objs | 1 + > stubs/arch-query-host-cpu-info.c | 8 ++++++++ > 6 files changed, 65 insertions(+) > create mode 100644 stubs/arch-query-host-cpu-info.c > > diff --git a/include/sysemu/arch_init.h b/include/sysemu/arch_init.h > index d690dfa..54215ab 100644 > --- a/include/sysemu/arch_init.h > +++ b/include/sysemu/arch_init.h > @@ -35,5 +35,6 @@ int kvm_available(void); > int xen_available(void); > > CpuDefinitionInfoList *arch_query_cpu_definitions(Error **errp); > +void arch_query_host_cpu_info(HostCPUInfo *r, bool migratable, Error **errp); > > #endif > diff --git a/qapi-schema.json b/qapi-schema.json > index 19e3ef2..d2f4879 100644 > --- a/qapi-schema.json > +++ b/qapi-schema.json > @@ -3047,6 +3047,42 @@ > ## > { 'command': 'query-cpu-definitions', 'returns': ['CpuDefinitionInfo'] } > > + > +## > +# @HostCPUInfo: > +# > +# Information on CPU capabilities supported by the current host. > +# > +# @qom-properties: #optional Values of CPU QOM properties corresponding > +# to CPU capabilities supported by the host. > +# > +# Most properties returned in qom-properties are boolean properties > +# indicating if a feature can be enabled in the current host. Other > +# non-boolean properties may be returned, the semantics of each property > +# depend on the architecture-specific code that handle them. > +# > +# Since: 2.7.0 Most places in .json files list just 'Since: x.y' rather than 'x.y.z', but we aren't consistent enough to insist either way on including or excluding a micro release number. > +## > +{ 'struct': 'HostCPUInfo', > + 'data': { '*qom-properties': 'any' } } This is a big hammer that makes the properties non-introspectible - a client can tell that properties will be returned, but cannot tell which properties to expect nor what format to expect for a given property name. I don't know that the interface could be made easily introspectible or not (it would probably require some QAPI unions, and a LOT more generated code). So it would be nice if we could explore how hard it would be to use a type-safe representation instead of 'any', before declaring that this is the best we can do. Or, it may be the sign of a bigger issue that we have no good way to introspect what qom properties to expect, in general (and that solving that would also solve this).