From: Marc Zyngier <maz@kernel.org>
To: Colton Lewis <coltonlewis@google.com>
Cc: kvm@vger.kernel.org, alexandru.elisei@arm.com,
pbonzini@redhat.com, corbet@lwn.net, linux@armlinux.org.uk,
catalin.marinas@arm.com, will@kernel.org, oliver.upton@linux.dev,
mizhang@google.com, joey.gouly@arm.com, suzuki.poulose@arm.com,
yuzenghui@huawei.com, mark.rutland@arm.com, shuah@kernel.org,
gankulkarni@os.amperecomputing.com, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
linux-perf-users@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v6 00/19] ARM64 PMU Partitioning
Date: Fri, 13 Feb 2026 08:11:01 +0000 [thread overview]
Message-ID: <86h5rlawru.wl-maz@kernel.org> (raw)
In-Reply-To: <gsnt8qcxhdpn.fsf@coltonlewis-kvm.c.googlers.com>
On Thu, 12 Feb 2026 21:08:36 +0000,
Colton Lewis <coltonlewis@google.com> wrote:
>
> Hey Marc, thanks for the review.
>
> Marc Zyngier <maz@kernel.org> writes:
>
> > On Mon, 09 Feb 2026 22:13:55 +0000,
> > Colton Lewis <coltonlewis@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.
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.
Please do.
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2026-02-13 8:11 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-09 22:13 [PATCH v6 00/19] ARM64 PMU Partitioning Colton Lewis
2026-02-09 22:13 ` [PATCH v6 01/19] arm64: cpufeature: Add cpucap for HPMN0 Colton Lewis
2026-02-09 22:13 ` [PATCH v6 02/19] KVM: arm64: Reorganize PMU includes Colton Lewis
2026-02-09 22:13 ` [PATCH v6 03/19] KVM: arm64: Reorganize PMU functions Colton Lewis
2026-02-09 22:13 ` [PATCH v6 04/19] perf: arm_pmuv3: Introduce method to partition the PMU Colton Lewis
2026-03-11 11:59 ` James Clark
2026-03-12 22:37 ` Colton Lewis
2026-03-11 17:45 ` James Clark
2026-03-12 22:37 ` Colton Lewis
2026-02-09 22:14 ` [PATCH v6 05/19] perf: arm_pmuv3: Generalize counter bitmasks Colton Lewis
2026-02-09 22:14 ` [PATCH v6 06/19] perf: arm_pmuv3: Keep out of guest counter partition Colton Lewis
2026-02-25 17:53 ` Colton Lewis
2026-03-11 12:00 ` James Clark
2026-03-12 22:39 ` Colton Lewis
2026-02-09 22:14 ` [PATCH v6 07/19] KVM: arm64: Set up FGT for Partitioned PMU Colton Lewis
2026-02-09 22:14 ` [PATCH v6 08/19] KVM: arm64: Define access helpers for PMUSERENR and PMSELR Colton Lewis
2026-02-10 4:30 ` kernel test robot
2026-02-10 5:20 ` kernel test robot
2026-02-09 22:14 ` [PATCH v6 09/19] KVM: arm64: Write fast path PMU register handlers Colton Lewis
2026-02-12 9:07 ` Marc Zyngier
2026-02-25 17:45 ` Colton Lewis
2026-02-09 22:14 ` [PATCH v6 10/19] KVM: arm64: Setup MDCR_EL2 to handle a partitioned PMU Colton Lewis
2026-02-09 22:14 ` [PATCH v6 11/19] KVM: arm64: Context swap Partitioned PMU guest registers Colton Lewis
2026-03-11 12:01 ` James Clark
2026-03-12 22:39 ` Colton Lewis
2026-02-09 22:14 ` [PATCH v6 12/19] KVM: arm64: Enforce PMU event filter at vcpu_load() Colton Lewis
2026-02-09 22:14 ` [PATCH v6 13/19] KVM: arm64: Implement lazy PMU context swaps Colton Lewis
2026-02-09 22:14 ` [PATCH v6 14/19] perf: arm_pmuv3: Handle IRQs for Partitioned PMU guest counters Colton Lewis
2026-02-10 4:51 ` kernel test robot
2026-02-10 7:32 ` kernel test robot
2026-02-09 22:14 ` [PATCH v6 15/19] KVM: arm64: Detect overflows for the Partitioned PMU Colton Lewis
2026-02-09 22:14 ` [PATCH v6 16/19] KVM: arm64: Add vCPU device attr to partition the PMU Colton Lewis
2026-02-10 5:55 ` kernel test robot
2026-03-05 10:16 ` James Clark
2026-03-12 22:13 ` Colton Lewis
2026-02-09 22:14 ` [PATCH v6 17/19] KVM: selftests: Add find_bit to KVM library Colton Lewis
2026-02-09 22:14 ` [PATCH v6 18/19] KVM: arm64: selftests: Add test case for partitioned PMU Colton Lewis
2026-02-09 22:14 ` [PATCH v6 19/19] KVM: arm64: selftests: Relax testing for exceptions when partitioned Colton Lewis
2026-02-10 8:49 ` [PATCH v6 00/19] ARM64 PMU Partitioning Marc Zyngier
2026-02-12 21:08 ` Colton Lewis
2026-02-13 8:11 ` Marc Zyngier [this message]
2026-02-25 17:40 ` Colton Lewis
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