Marc Zyngier <[email protected]> writes:
On Thu, 12 Feb 2026 21:08:36 +0000, Colton Lewis <[email protected]> wrote:
Hey Marc, thanks for the review.
Marc Zyngier <[email protected]> writes:
> On Mon, 09 Feb 2026 22:13:55 +0000, > Colton Lewis <[email protected]> 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.
No. *any* VMM. QEMU, kvmtool, crosvm, firecrackpoter, whichever you want.
I had hoped that the use in the selftest was sufficient to show how to use the uAPI.
The selftests are absolutely pointless, like 99% of all selftests. They don't demonstrate how the userspace API works, now how configuring the PMU is ordered with the rest of the save/restore flow.
If not, I can send out an example QEMU patch to the QEMU ARM mailing list.
Okay I sent one to you, qemu-arm, and everyone else I asked to review this series.
