[0/2] APICv-related fixes for inhibits and tracepoint

Message

Alejandro Jimenez April 17, 2024, 8:08 p.m. UTC

Patch 1 fixes an issue when avic=0 (current default) where
APICV_INHIBIT_REASON_ABSENT remains set even after an in-kernel local APIC has
been created. e.g. tracing the inhibition tracepoint shows:

<...>-196432  [247] ..... 70380.628931: kvm_apicv_inhibit_changed: set reason=2, inhibits=0x4
<...>-196432  [247] ..... 70380.628941: kvm_apicv_inhibit_changed: set reason=0, inhibits=0x5

and the reason=2 inhibit is not removed after the local APIC is created.

Patch 2 modifies the wording in the pi_irte_update tracepoint to make it clear
that it is used by the posted interrupt implementation of both vendors. I have
reservations about modifying the tracepoint output and breaking user scripts,
but according to recent discussions tracepoints are not strictly a stable ABI,
so I'd consider this minor change to avoid confusion around this area.

Thank you,
Alejandro

Alejandro Jimenez (2):
  KVM: x86: Only set APICV_INHIBIT_REASON_ABSENT if APICv is enabled
  KVM: x86: Remove VT-d mention in posted interrupt tracepoint

 arch/x86/kvm/trace.h |  4 ++--
 arch/x86/kvm/x86.c   | 15 ++++++++++++++-
 2 files changed, 16 insertions(+), 3 deletions(-)


base-commit: 2d181d84af38146748042a6974c577fc46c3f1c3