KVM: arm64: Rework timer offsetting for fun and profit

This series aims at satisfying multiple goals:

- allow a VMM to atomically restore a timer offset for a whole VM
  instead of updating the offset each time a vcpu get its counter
  written

- allow a VMM to save/restore the physical timer context, something
  that we cannot do at the moment due to the lack of offsetting

- provide a framework that is suitable for NV support, where we get
  both global and per timer, per vcpu offsetting

We fix a couple of issues along the way, both from a stylistic and
correctness perspective. This results in a new per VM KVM API that
allows a pair of global offsets to be set at any point in time,
overriding the timer counter writeback.

This has been moderately tested with nVHE, VHE and NV. I do not have
access to CNTPOFF-aware HW, so the jury is still out on that one. Note
that the NV patches in this series are here to give a perspective on
how this gets used.

I've updated the arch_timer selftest to allow offsets to be provided
from the command line, but the arch_test is pretty flimsy and tends to
fail with an error==EINTR, even without this series. Something to
investigate.

Note that this is at best 6.4 material. I have a branch stashed at [1]
and based on kvmarm/next.

Thanks,

	M.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-p...

Marc Zyngier (16):
  arm64: Add CNTPOFF_EL2 register definition
  arm64: Add HAS_ECV_CNTPOFF capability
  kvm: arm64: Expose {un,}lock_all_vcpus() to the reset of KVM
  KVM: arm64: timers: Use a per-vcpu, per-timer accumulator for
    fractional ns
  KVM: arm64: timers: Convert per-vcpu virtual offset to a global value
  KVM: arm64: timers: Use CNTPOFF_EL2 to offset the physical timer
  KVM: arm64: timers: Allow physical offset without CNTPOFF_EL2
  KVM: arm64: timers: Allow userspace to set the counter offsets
  KVM: arm64: timers: Allow save/restoring of the physical timer
  KVM: arm64: timers: Rationalise per-vcpu timer init
  KVM: arm64: Document KVM_ARM_SET_CNT_OFFSETS and co
  KVM: arm64: nv: timers: Add a per-timer, per-vcpu offset
  KVM: arm64: nv: timers: Support hyp timer emulation
  KVM: arm64: selftests: Add physical timer registers to the sysreg list
  KVM: arm64: selftests: Augment existing timer test to handle variable
    offsets
  KVM: arm64: selftests: Deal with spurious timer interrupts

 Documentation/virt/kvm/api.rst                |  47 ++
 arch/arm64/include/asm/kvm_host.h             |  14 +
 arch/arm64/include/uapi/asm/kvm.h             |  15 +
 arch/arm64/kernel/cpufeature.c                |  11 +
 arch/arm64/kvm/arch_timer.c                   | 443 ++++++++++++++----
 arch/arm64/kvm/arm.c                          |  47 ++
 arch/arm64/kvm/guest.c                        |  29 +-
 arch/arm64/kvm/hyp/nvhe/timer-sr.c            |  18 +-
 arch/arm64/kvm/hypercalls.c                   |   2 +-
 arch/arm64/kvm/trace_arm.h                    |   6 +-
 arch/arm64/kvm/vgic/vgic-kvm-device.c         |  38 --
 arch/arm64/kvm/vgic/vgic.c                    |  15 +
 arch/arm64/kvm/vgic/vgic.h                    |   3 -
 arch/arm64/tools/cpucaps                      |   1 +
 arch/arm64/tools/sysreg                       |   4 +
 include/clocksource/arm_arch_timer.h          |   1 +
 include/kvm/arm_arch_timer.h                  |  32 +-
 include/kvm/arm_vgic.h                        |   1 +
 include/uapi/linux/kvm.h                      |   3 +
 .../selftests/kvm/aarch64/arch_timer.c        |  26 +-
 .../selftests/kvm/aarch64/get-reg-list.c      |   5 +-
 21 files changed, 603 insertions(+), 158 deletions(-)

-- 
2.34.1


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