[PATCH v6 00/19] ARM64 PMU Partitioning

[Colton Lewis]

Hey Marc, thanks for the review.

Marc Zyngier <maz at kernel.org> writes:

> On Mon, 09 Feb 2026 22:13:55 +0000,
> Colton Lewis <coltonlewis at google.com> wrote:

>> This series creates a new PMU scheme on ARM, a partitioned PMU that
>> allows reserving a subset of counters for more direct guest access,
>> significantly reducing overhead. More details, including performance
>> benchmarks, can be read in the v1 cover letter linked below.

>> An overview of what this series accomplishes was presented at KVM
>> Forum 2025. Slides [1] and video [2] are linked below.

>> IMPORTANT: This iteration does not yet implement the dynamic counter
>> reservation approach suggested by Will Deacon in January [3]. I am
>> working on it, but wanted to send this version first to keep momentum
>> going and ensure I've addressed all issues besides that.

> [...]

> As I have asked before, this is missing an example of how userspace is
> going to use this. Without it, it is impossible to correctly review
> this series.

> Please consider this as a blocker.

Understood. I remember you asking for a QEMU patch specifically.

I had hoped that the use in the selftest was sufficient to show how to
use the uAPI. If not, I can send out an example QEMU patch to the QEMU
ARM mailing list.

> Thanks,

> 	M.

> --
> Without deviation from the norm, progress is not possible.