Re: [PATCH v2 1/1] qemu: Add support for RAPL MSRs feature

On Thu, Aug 22, 2024 at 17:59:47 +0200, Anthony Harivel wrote: > Add the support in libvirt to activate the RAPL feature in QEMU. > > This feature is activated with -accel kvm,rapl=true,path=/path/sock.sock > in QEMU. > > The feature is activated in libvirt with the following XML > configuration: > > <kvm> > [...] > <rapl state ='on' socket='/run/qemu-vmsr-helper.sock'/> > [...] > </kvm> > > See: https://gitlab.com/qemu-project/qemu/-/commit/0418f90809aea5b375c859e744c... > > Signed-off-by: Anthony Harivel <aharivel(a)redhat.com&gt; > --- > docs/formatdomain.rst | 2 ++ > src/conf/domain_conf.c | 18 ++++++++++++++++++ > src/conf/domain_conf.h | 2 ++ > src/conf/schemas/domaincommon.rng | 10 ++++++++++ > src/qemu/qemu_command.c | 11 +++++++++++ > tests/qemuxmlconfdata/kvm-features-off.xml | 1 + > .../kvm-features.x86_64-latest.args | 2 +- > tests/qemuxmlconfdata/kvm-features.xml | 1 + > 8 files changed, 46 insertions(+), 1 deletion(-) [...] > @@ -7176,6 +7179,14 @@ qemuBuildAccelCommandLine(virCommand *cmd, > def->kvm_features->features[VIR_DOMAIN_KVM_DIRTY_RING] == VIR_TRISTATE_SWITCH_ON) { > virBufferAsprintf(&buf, ",dirty-ring-size=%d", def->kvm_features->dirty_ring_size); > } This should be separated via a newline. > + if (def->features[VIR_DOMAIN_FEATURE_KVM] == VIR_TRISTATE_SWITCH_ON && > + def->kvm_features->features[VIR_DOMAIN_KVM_RAPL] == VIR_TRISTATE_SWITCH_ON) { > + virBufferAddLit(&buf, ",rapl=true"); > + > + if (def->kvm_features->rapl_helper_socket != NULL) { > + virBufferAsprintf(&buf, ",rapl-helper-socket=%s", def->kvm_features->rapl_helper_socket); > + } > + } > break; > > case VIR_DOMAIN_VIRT_HVF: Apart from that the rest looks good providing the following: I suppose that the 'rapl-helper-socket' is a shared (multiple qemu's use it) resource set up beforehand by the admin. Right?

If that is the case that means the lifecycle of the daemon and permissions (including selinux) for accessing the socket are not something that libvirt needs to deal with. If either of them isn't true please outline how that socket is to be used to see how libvirt will need to approach it.