[PATCH 0/2] KVM: arm64: vgic: LPI fixes for redistributors with LPIs disabled

[Fuad Tabba <fuad.tabba@linux.dev>]

Hi folks,

Two fixes on top of Marc's cross-CPU vcpu pausing series [1], for LPIs
whose redistributor has LPIs disabled. Without them, the guest can take
such an LPI with EnableLPIs clear, or lose one mapped before it enables
them.

The first is the vgic_target_oracle() change Oliver suggested on v2 of
that series [2]. It stops an LPI from being queued to a redistributor
with EnableLPIs clear once the disable path has retired the vCPU's AP
list. With that check, the path has to pause the vCPU before clearing
EnableLPIs, so that the retire still finds its LPIs.

With the second, an LPI mapped while its redistributor has LPIs
disabled keeps its pending bit when they're enabled. The second relies
on the first to keep such an LPI off the AP list until the enable.

Reproducers for the INVALL case in the first and the map in the second
fail in every run without the patch and pass with it.

Based on kvm-arm64/cross-vcpu-sync as merged in kvmarm/fixes, which the
first builds on (e99ff76f4a02b; also applies to kvmarm/fixes
309e1d2215255).

Cheers,
/fuad

[1] https://lore.kernel.org/all/20261015100539.1011760-1-maz@kernel.org/
[2] https://lore.kernel.org/all/asf87i2RDh-WksL-@kernel.org/

Fuad Tabba (2):
  KVM: arm64: vgic: Don't forward LPIs to a redistributor with LPIs
    disabled
  KVM: arm64: vgic-v3: Don't drop a pending LPI mapped with LPIs
    disabled

 arch/arm64/kvm/vgic/vgic-mmio-v3.c | 31 ++++++++++++++++--------------
 arch/arm64/kvm/vgic/vgic-v3.c      |  3 ++-
 arch/arm64/kvm/vgic/vgic.c         | 12 ++++++++----
 3 files changed, 27 insertions(+), 19 deletions(-)


base-commit: e99ff76f4a02be8542e2c3ecc8843d7339a0200d
-- 
2.47.3