linux-kernel - [PATCH v4 00/23] ARM64 PMU Partitioning

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Message-ID: <20250714225917.1396543-1-coltonlewis@google.com>
Date: Mon, 14 Jul 2025 22:58:54 +0000
From: Colton Lewis <coltonlewis@...gle.com>
To: kvm@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jonathan Corbet <corbet@....net>, 
	Russell King <linux@...linux.org.uk>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Mingwei Zhang <mizhang@...gle.com>, Joey Gouly <joey.gouly@....com>, 
	Suzuki K Poulose <suzuki.poulose@....com>, Zenghui Yu <yuzenghui@...wei.com>, 
	Mark Rutland <mark.rutland@....com>, Shuah Khan <shuah@...nel.org>, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, linux-perf-users@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, Colton Lewis <coltonlewis@...gle.com>
Subject: [PATCH v4 00/23] ARM64 PMU Partitioning

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.

v4:

* Apply Mark Brown's non-UNDEF FGT control commit to the PMU FGT
  controls and calculate those controls with the others in
  kvm_calculate_traps()

* Introduce lazy context swaps for guests that only turns on for
  guests that have enabled partitioning and accessed PMU registers.

* Rename pmu-part.c to pmu-direct.c because future features might
  achieve direct PMU access without partitioning.

* Better explain certain commits, such as why the untrapped registers
  are safe to untrap.

* Reduce the PMU include cleanup down to only what is still necessary
  and explain why.

v3:
https://lore.kernel.org/kvm/20250626200459.1153955-1-coltonlewis@google.com/

v2:
https://lore.kernel.org/kvm/20250620221326.1261128-1-coltonlewis@google.com/

v1:
https://lore.kernel.org/kvm/20250602192702.2125115-1-coltonlewis@google.com/

Colton Lewis (21):
  arm64: cpufeature: Add cpucap for HPMN0
  KVM: arm64: Reorganize PMU functions
  perf: arm_pmuv3: Introduce method to partition the PMU
  perf: arm_pmuv3: Generalize counter bitmasks
  perf: arm_pmuv3: Keep out of guest counter partition
  KVM: arm64: Account for partitioning in kvm_pmu_get_max_counters()
  KVM: arm64: Set up FGT for Partitioned PMU
  KVM: arm64: Writethrough trapped PMEVTYPER register
  KVM: arm64: Use physical PMSELR for PMXEVTYPER if partitioned
  KVM: arm64: Writethrough trapped PMOVS register
  KVM: arm64: Write fast path PMU register handlers
  KVM: arm64: Setup MDCR_EL2 to handle a partitioned PMU
  KVM: arm64: Account for partitioning in PMCR_EL0 access
  KVM: arm64: Context swap Partitioned PMU guest registers
  KVM: arm64: Enforce PMU event filter at vcpu_load()
  KVM: arm64: Extract enum debug_owner to enum vcpu_register_owner
  KVM: arm64: Implement lazy PMU context swaps
  perf: arm_pmuv3: Handle IRQs for Partitioned PMU guest counters
  KVM: arm64: Inject recorded guest interrupts
  KVM: arm64: Add ioctl to partition the PMU when supported
  KVM: arm64: selftests: Add test case for partitioned PMU

Marc Zyngier (1):
  KVM: arm64: Reorganize PMU includes

Mark Brown (1):
  KVM: arm64: Introduce non-UNDEF FGT control

 Documentation/virt/kvm/api.rst                |  21 +
 arch/arm/include/asm/arm_pmuv3.h              |  38 +
 arch/arm64/include/asm/arm_pmuv3.h            |  61 +-
 arch/arm64/include/asm/kvm_host.h             |  34 +-
 arch/arm64/include/asm/kvm_pmu.h              | 123 +++
 arch/arm64/include/asm/kvm_types.h            |   7 +-
 arch/arm64/kernel/cpufeature.c                |   8 +
 arch/arm64/kvm/Makefile                       |   2 +-
 arch/arm64/kvm/arm.c                          |  22 +
 arch/arm64/kvm/debug.c                        |  33 +-
 arch/arm64/kvm/hyp/include/hyp/debug-sr.h     |   6 +-
 arch/arm64/kvm/hyp/include/hyp/switch.h       | 181 ++++-
 arch/arm64/kvm/pmu-direct.c                   | 395 ++++++++++
 arch/arm64/kvm/pmu-emul.c                     | 674 +---------------
 arch/arm64/kvm/pmu.c                          | 725 ++++++++++++++++++
 arch/arm64/kvm/sys_regs.c                     | 137 +++-
 arch/arm64/tools/cpucaps                      |   1 +
 arch/arm64/tools/sysreg                       |   6 +-
 drivers/perf/arm_pmuv3.c                      | 128 +++-
 include/linux/perf/arm_pmu.h                  |   1 +
 include/linux/perf/arm_pmuv3.h                |  14 +-
 include/uapi/linux/kvm.h                      |   4 +
 tools/include/uapi/linux/kvm.h                |   2 +
 .../selftests/kvm/arm64/vpmu_counter_access.c |  62 +-
 24 files changed, 1910 insertions(+), 775 deletions(-)
 create mode 100644 arch/arm64/kvm/pmu-direct.c


base-commit: 79150772457f4d45e38b842d786240c36bb1f97f
--
2.50.0.727.gbf7dc18ff4-goog