> > On Mon, Jan 15, 2018 at 12:04:55 -0200, Eduardo Habkost wrote: > > > CCing libvirt developers. > > ... > > > This case is slightly more problematic, however: the new feature is > > > actually migratable (under very controlled circumstances) because of > > > patch 2/2, but it is not migration-safe[1]. This means libvirt > > > shouldn't include it in "host-model" expansion (which uses the > > > query-cpu-model-expansion QMP command) until we make the feature > > > migration-safe. > > > > > > For QEMU, this means the feature shouldn't be returned by > > > "query-cpu-model-expansion type=static model=max" (but it can be > > > returned by "query-cpu-model-expansion type=full model=max"). > > > > > > Jiri, it looks like libvirt uses type=full on > > > query-cpu-model-expansion on x86. It needs to use type=static[2], > > > or it will have no way to find out if a feature is migration-safe or > > > not. > > ... > > > [2] It looks like libvirt uses type=full because it wants to get > > > all QOM property aliases returned. In this case, one > > > solution for libvirt is to use: > > > > > > static_expansion = query_cpu_model_expansion(type=static, model) > > > all_props = query_cpu_model_expansion(type=full, > > > static_expansion) > > > > This is exactly what libvirt is doing (with model = "host") ever since > > query-cpu-model-expansion support was implemented for x86. > > Oh, now I see that the x86 code uses > QEMU_MONITOR_CPU_MODEL_EXPANSION_STATIC_FULL and not just QEMU_MONITOR_CPU_MODEL_EXPANSION_FULL. Nice! > So, I need to add Intel PT feature in "X86CPUDefinition builtin_x86_defs[]" so that we can get this CPUID in specific CPU model not only "-cpu host". Is that right? Intel PT is first supported in Intel Core M and 5th generation Intel Core processors that are based on the Intel micro-architecture code name Broadwell but Intel PT use EPT is first supported in Ice Lake. Intel PT virtualization depend on PT use EPT. I will add Intel PT to "Broadwell" CPU model and later to make sure a "Broadwell" guest can use Intel PT if the host is Ice Lake. Thanks, Luwei Kang
