Re: [PATCH v3 0/8] KVM: x86: Add AMD Guest PerfMonV2 PMU support

Sean Christopherson
2023-01-20T01:13:44Z

On Fri, Nov 11, 2022, Like Xu wrote:
> Starting with Zen4, core PMU on AMD platforms such as Genoa and
> Ryzen-7000 will support PerfMonV2, and it is also compatible with
> legacy PERFCTR_CORE behavior and msr addresses.
>
> If you don't have access to the hardware specification, the commits
> d6d0c7f681fd..7685665c390d for host perf can also bring a quick
> overview. Its main change is the addition of three msr's equivalent
> to Intel V2, namely global_ctrl, global_status, global_status_clear.
>
> It is worth noting that this feature is very attractive for reducing the
> overhead of PMU virtualization, since multiple msr accesses to multiple
> counters will be replaced by a single access to the global register,
> plus more accuracy gain when multiple guest counters are used.

Some minor nits, though I haven't looked at the meat of the series yet. I'll
give this a thorough review early next week (unless I'm extra ambitious tomorrow).