On 18/08/2020 10:34, Olaf Hering wrote: > Since commit 6b85e427098cce1a6d386b3bae2f0c7ce86e47f7 'xen-cpuid -p' shows > the cpuid policies. I think these policies define what a domU will get to see > when cpuid() is invoked, or when MSRs are accessed.
Only a subset of the read-only MSRs - those which effectively behave like further feature information. 0xce is Intel-only MSR which we actually advertise consistently, to offer CPUID faulting capabilities to VMs. Future MSRs are going to be MSR_ARCH_CAPS (when we've got the toostack side of the work done), then MSR_FEATURE_CONTROL and all the VMX MSRs for Intel nested virt. > Unfortunately this commit shows only the raw hex values, which makes it > difficult to compare output from different physical hosts. I think the actual > policy values could be shown in expanded form, similar to what 'xen-cpuid -d' > would show. > > Did you ever consider to show the expanded form for policies? Using a bit of sed, you can transform the CPUID part into something which `cpuid` can interpret and decode. I'm not aware of anything for the MSR side yet. As always, xen-cpuid is a debug tool, and tends to only gain new functionality on an as-time-permits basis. I do have a few vague plans to extend it, but they are definitely not higher priority than getting MSR_ARCH_CAPS working. ~Andrew
