[PATCH 0/7] KVM: arm64: Fix cross-CPU vcpu pausing

[Marc Zyngier <maz@kernel.org>]

This series is a follow-up on what I previously posted at [1], and has
now grown a few more fixes, and inherited an improvement from Oliver.
Some of the fixes have already been merged, so what we have here
serves a slightly different goal.

As we are simplifying (and fixing) a bunch of vgic behaviours, it
becomes necessary to pause one (or all) vcpu(s) and *reliably*
introspect the state of interrupts.

It appears that the current KVM behaviour is remarkably broken:

- OUTSIDE_GUEST_MODE is published too early, before we have resynced
  the state, making it unreliable

- IN_GUEST_MODE is published too late, once we have already placed
  volatile state on the CPU (interrupts, for example), and making the
  in-memory state stale (edge pending bits are a particular sore spot)

- self-generated requests are sometimes posted too late, after we have
  committed to entering the guest, and are therefore delayed

- the pausing mechanism itself is unreliable, as it has no requirement
  to be called whilst holding a global lock, and therefore is able to
  nest, while it is backed by a simple boolean

This series addresses these defects, and builds on top of it to:

- add pausing to a single vcpu in addition to the full VM pausing

- convert LPI disabling and the MOVALL command to vcpu pausing

Patches on top of -rc6, most of them being Cc stable without any
qualification (this has been broken for as long as I can remember).

[1] https://lore.kernel.org/r/20260929093548.3598547-1-maz@kernel.org

Marc Zyngier (6):
  KVM: arm64: nv: Move L2->L1 switch on interrupt early
  KVM: arm64: Move OUTSIDE_GUEST_MODE publication past context being
    saved
  KVM: arm64: Move IN_GUEST_MODE ahead of state being loaded
  KVM: arm64: Turn vcpu->arch.pause into a counter
  KVM: arm64: vgic: Stop the target vcpu when disabling LPIs
  KVM: arm64: vgic-its: Stop the VM when handling MOVALL

Oliver Upton (1):
  KVM: arm64: Add helpers to halt a vCPU

 arch/arm64/include/asm/kvm_host.h  |  9 ++--
 arch/arm64/kvm/arm.c               | 69 ++++++++++++++++++++----------
 arch/arm64/kvm/nested.c            |  8 ++++
 arch/arm64/kvm/vgic/vgic-its.c     | 11 +++++
 arch/arm64/kvm/vgic/vgic-mmio-v3.c | 10 +++++
 arch/arm64/kvm/vgic/vgic.c         |  8 +---
 6 files changed, 81 insertions(+), 34 deletions(-)

-- 
2.47.3