[PATCH v2 00/10] arm64: Add initial support for FEAT_WFxT

Marc Zyngier
2022-04-19T18:34:20Z

The ARMv8.7 WFxT feature is a new take on the good old WFI/WFE
instructions as they behave the same way, only taking an extra timeout
parameter.

This small series aims at adding the minimal support for this feature,
enabling it for both the kernel and KVM.

A potential addition to this series would be to remove the event
generation from the counters, and rely on the timeout where it
matters (spinlocks?). Feedback welcome.

Patches on top of 5.18-rc2, tested of the FVP AEM.

* From v1 [1]:
- Properly generate traces even if the deadline has already expired
- Collect RBs, with thanks.

[1] https://lore.kernel.org/r/20220412131303.504690-1-maz@kernel.org

Marc Zyngier (10):
arm64: Expand ESR_ELx_WFx_ISS_TI to match its ARMv8.7 definition
arm64: Add RV and RN fields for ESR_ELx_WFx_ISS
KVM: arm64: Simplify kvm_cpu_has_pending_timer()
KVM: arm64: Introduce kvm_counter_compute_delta() helper
KVM: arm64: Handle blocking WFIT instruction
KVM: arm64: Offer early resume for non-blocking WFxT instructions
KVM: arm64: Expose the WFXT feature to guests
arm64: Add HWCAP advertising FEAT_WFXT
arm64: Add wfet()/wfit() helpers
arm64: Use WFxT for __delay() when possible

Documentation/arm64/cpu-feature-registers.rst | 2 +
Documentation/arm64/elf_hwcaps.rst | 4 ++
arch/arm64/include/asm/barrier.h | 4 ++
arch/arm64/include/asm/esr.h | 8 +++-
arch/arm64/include/asm/hwcap.h | 1 +
arch/arm64/include/asm/kvm_host.h | 1 +
arch/arm64/include/uapi/asm/hwcap.h | 1 +
arch/arm64/kernel/cpufeature.c | 13 +++++
arch/arm64/kernel/cpuinfo.c | 1 +
arch/arm64/kvm/arch_timer.c | 47 ++++++++++++-------
arch/arm64/kvm/arm.c | 6 +--
arch/arm64/kvm/handle_exit.c | 35 ++++++++++++--
arch/arm64/kvm/sys_regs.c | 2 +
arch/arm64/lib/delay.c | 12 ++++-
arch/arm64/tools/cpucaps | 1 +
include/kvm/arm_arch_timer.h | 2 -
16 files changed, 110 insertions(+), 30 deletions(-)

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2.34.1