Re: [PATCH 4/4] x86/tsx: Add cmdline tsx=fake to not clear CPUID bits RTM and HLE

On Wed, Jul 7, 2021 at 8:09 AM Eduardo Habkost <ehabkost(a)redhat.com&gt; wrote: > > CCing libvir-list, Jiri Denemark, Michal Privoznik, so they are aware > that the definition of "supported CPU features" will probably become a > bit more complex in the future. Has there ever been a clear definition? Family, model, and stepping, for instance: are these the only values supported? That would make cross-platform migration impossible. What about the vendor string? Is that the only value supported? That would make cross-vendor migration impossible. For the maximum input value for basic CPUID information (CPUID.0H:EAX), is that the only value supported, or is it the maximum value supported? On the various individual feature bits, does a '1' imply that '0' is also supported, or is '1' the only value supported? What about the feature bits with reversed polarity (e.g. CPUID.(EAX=07H,ECX=0):EBX.FDP_EXCPTN_ONLY[bit 6])? This API has never made sense to me. I have no idea how to interpret what it is telling me.