On Fri, Dec 31, 2021, Like Xu wrote: > On 31/12/2021 2:13 am, Sean Christopherson wrote: > > On Fri, Dec 10, 2021, Like Xu wrote: > > > The new hardware facility supporting guest PEBS is only available on > > > Intel Ice Lake Server platforms for now. KVM will check this field > > > through perf_get_x86_pmu_capability() instead of hard coding the cpu > > > models in the KVM code. If it is supported, the guest PEBS capability > > > will be exposed to the guest. > > > > So what exactly is this new feature? I've speed read the cover letter and a few > > changelogs and didn't find anything that actually explained when this feature does. > > > > Please check Intel SDM Vol3 18.9.5 for this "EPT-Friendly PEBS" feature. > > I assume when an unfamiliar feature appears in the patch SUBJECT, > the reviewer may search for the exact name in the specification. C'mon, seriously? How the blazes am I supposed to know that the feature name is EPT-Friendly PEBS? Or that it's even in the SDM (it's not in the year-old version of the SDM I currently have open) versus one of the many ISE docs? This is not hard. Please spend the 30 seconds it takes to write a small blurb so that reviewers don't have to spend 5+ minutes wondering WTF this does. Add support for EPT-Friendly PEBS, a new CPU feature that enlightens PEBS to translate guest linear address through EPT, and facilitates handling VM-Exits that occur when accessing PEBS records. More information can be found in the <date> release of Intel's SDM, Volume 3, 18.9.5 "EPT-Friendly PEBS".
