linux-kernel - [PATCH v7 00/16] KVM: arm64: Optimise FPSIMD context switching

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Date:   Wed,  9 May 2018 17:12:49 +0100
From:   Dave Martin <Dave.Martin@....com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     linux-arm-kernel@...ts.infradead.org,
        Christoffer Dall <cdall@...nel.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Oleg Nesterov <oleg@...hat.com>
Subject: [PATCH v7 00/16] KVM: arm64: Optimise FPSIMD context switching

Note: Most of these patches are Arm-specific.  People not Cc'd on the
whole series can find it in the linux-arm-kernel archive [2].

This series aims to improve the way FPSIMD context is handled by KVM.
Only minor changes have been made since the previous v6 [1], though
this posting does apply a couple of fixes.

The changes are summarised in the individual patches.

Reviewers please note:

 * Patch 6 is new, and does some minor refactoring to help fix an SVE
   context switching issue on the host, observed during stress-testing
   of v6 on an SVE-enabled model (the actual fix, using this
   refactoring, is incorporated in patch 8).

 * Patch 8 is missing Reviewed-bys/Acked-bys (thanks Marc, but I
   stripped yours in the end due to nontrivial changes.  Reviewer
   attention on these patches would be much appreciated.

Some testing done on Juno and the Arm fast model (arm64), including
combinations of (non-)SVE and (non-)VHE configurations.

Cheers
---Dave

[1] [PATCH v6 00/15] KVM: arm64: Optimise FPSIMD context switching
http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/576355.html

[2] linux-arm-kernel archive
http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/thread.html


Christoffer Dall (1):
  KVM: arm/arm64: Introduce kvm_arch_vcpu_run_pid_change

Dave Martin (15):
  thread_info: Add update_thread_flag() helpers
  arm64: Use update{,_tsk}_thread_flag()
  KVM: arm64: Convert lazy FPSIMD context switch trap to C
  arm64: fpsimd: Generalise context saving for non-task contexts
  arm64/sve: Refactor user SVE trap maintenance for external use
  KVM: arm64: Repurpose vcpu_arch.debug_flags for general-purpose flags
  KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing
  arm64/sve: Move read_zcr_features() out of cpufeature.h
  arm64/sve: Switch sve_pffr() argument from task to thread
  arm64/sve: Move sve_pffr() to fpsimd.h and make inline
  KVM: arm64: Save host SVE context as appropriate
  KVM: arm64: Remove eager host SVE state saving
  KVM: arm64: Remove redundant *exit_code changes in fpsimd_guest_exit()
  KVM: arm64: Fold redundant exit code checks out of fixup_guest_exit()
  KVM: arm64: Invoke FPSIMD context switch trap from C

 arch/arm/include/asm/kvm_host.h     |   9 ++-
 arch/arm64/Kconfig                  |   7 ++
 arch/arm64/include/asm/cpufeature.h |  29 -------
 arch/arm64/include/asm/fpsimd.h     |  21 +++++
 arch/arm64/include/asm/kvm_asm.h    |   3 -
 arch/arm64/include/asm/kvm_host.h   |  32 +++++---
 arch/arm64/include/asm/processor.h  |   2 +
 arch/arm64/kernel/fpsimd.c          | 148 ++++++++++++++++++------------------
 arch/arm64/kernel/ptrace.c          |   1 +
 arch/arm64/kvm/Kconfig              |   1 +
 arch/arm64/kvm/Makefile             |   2 +-
 arch/arm64/kvm/debug.c              |   8 +-
 arch/arm64/kvm/fpsimd.c             | 111 +++++++++++++++++++++++++++
 arch/arm64/kvm/hyp/debug-sr.c       |   6 +-
 arch/arm64/kvm/hyp/entry.S          |  43 -----------
 arch/arm64/kvm/hyp/hyp-entry.S      |  19 -----
 arch/arm64/kvm/hyp/switch.c         | 124 +++++++++++++++++++++---------
 arch/arm64/kvm/hyp/sysreg-sr.c      |   4 +-
 arch/arm64/kvm/sys_regs.c           |   9 +--
 include/linux/kvm_host.h            |   9 +++
 include/linux/sched.h               |   6 ++
 include/linux/thread_info.h         |  11 +++
 virt/kvm/Kconfig                    |   3 +
 virt/kvm/arm/arm.c                  |  25 +++++-
 virt/kvm/kvm_main.c                 |   7 +-
 25 files changed, 405 insertions(+), 235 deletions(-)
 create mode 100644 arch/arm64/kvm/fpsimd.c

-- 
2.1.4