[PATCH 0/4] KVM: arm64: vgic: Stop migrating IRQ from vgic_prune_ap_list()

[Oliver Upton <oupton@kernel.org>]

The VGIC has been getting a lot of undesired attention lately, as
there's plenty of weird and wonderful ways that the guest can play games
with KVM. My general impression on the whole matter is that modifying AP
lists remotely is a giant mess, with the worst offender being
vgic_prune_ap_list().

This series aims to sidestep the issue by only recalling IRQs from an AP
list if the vCPU has been paused. Keeping the overheads reasonable also
means adding support for pausing a single vCPU instead of the entire
VM, so update the eligible users of kvm_arm_halt_guest() to something
more relaxed while we're at it.

Marc, this series applies on top of your own for LPI malice [1]. You'll
note that I've taken some of it for 7.3 while leaving the rest for you
to take in 7.4, I'm perfectly happy with Patch 3 and 4 getting squashed
into the corresponding bits of your own series if you prefer.

Tested semi-rigorously on an Altra machine and the Orion board, using
both real guests and an LLM-generated selftest specific for migrating
pending LPIs. The latter was way too big to make sense of, I'll try and
post a test if I can it into something tidy.

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

Oliver Upton (4):
  KVM: arm64: Add helpers to halt a vCPU
  KVM: arm64: vgic: Move IRQ migrations out of vgic_prune_ap_list()
  KVM: arm64: vgic-v3: Only pause the targeted vCPU when disabling LPIs
  KVM: arm64: vgic-v3: Pause the source vCPU when processing MOVALL cmd

 arch/arm64/include/asm/kvm_host.h  |   2 +
 arch/arm64/kvm/arm.c               |  18 ++-
 arch/arm64/kvm/vgic/vgic-its.c     |  19 ++-
 arch/arm64/kvm/vgic/vgic-mmio-v2.c |  11 +-
 arch/arm64/kvm/vgic/vgic-mmio-v3.c |  18 ++-
 arch/arm64/kvm/vgic/vgic.c         | 184 +++++++++++++++++------------
 arch/arm64/kvm/vgic/vgic.h         |  24 ++++
 include/kvm/arm_vgic.h             |   1 +
 8 files changed, 164 insertions(+), 113 deletions(-)


base-commit: cfaf3b76669d386912a91103671691692f81c316
-- 
2.47.3