[RFC PATCH 0/4] Add support for ARMv8.6 TWED feature

[Jingyi Wang]

TWE Delay is an optional feature in ARMv8.6 Extentions. There is a
performance benefit in waiting for a period of time for an event to
arrive before taking the trap as it is common that event will arrive
“quite soon” after executing the WFE instruction.

This series adds support for TWED feature and implements TWE delay
value dynamic adjustment.

Thanks for Shameer's advice on this series. The function of this patch
has been tested on TWED supported hardware and the performance of it is
still on test, any advice will be welcomed.

Jingyi Wang (2):
  KVM: arm64: Make use of TWED feature
  KVM: arm64: Use dynamic TWE Delay value

Zengruan Ye (2):
  arm64: cpufeature: TWED support detection
  KVM: arm64: Add trace for TWED update

 arch/arm64/Kconfig                   | 10 +++++
 arch/arm64/include/asm/cpucaps.h     |  3 +-
 arch/arm64/include/asm/kvm_arm.h     |  5 +++
 arch/arm64/include/asm/kvm_emulate.h | 38 ++++++++++++++++++
 arch/arm64/include/asm/kvm_host.h    | 19 ++++++++-
 arch/arm64/include/asm/virt.h        |  8 ++++
 arch/arm64/kernel/cpufeature.c       | 12 ++++++
 arch/arm64/kvm/arm.c                 | 58 ++++++++++++++++++++++++++++
 arch/arm64/kvm/handle_exit.c         |  2 +
 arch/arm64/kvm/trace_arm.h           | 21 ++++++++++
 10 files changed, 174 insertions(+), 2 deletions(-)

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2.19.1