[PATCH 0/8] x86/irq: KVM: Optimize KVM's PIR harvesting

From: Sean Christopherson
Date: Fri Mar 14 2025 - 23:06:45 EST


Optimizing KVM's PIR harvesting using the same techniques as posted MSIs,
most notably to use 8-byte accesses on 64-bit kernels (/facepalm).

Fix a few warts along the way, and finish up by adding a helper to dedup
the PIR harvesting code between KVM and posted MSIs.

Sean Christopherson (8):
x86/irq: Ensure initial PIR loads are performed exactly once
x86/irq: Track if IRQ was found in PIR during initial loop (to load
PIR vals)
KVM: VMX: Ensure vIRR isn't reloaded at odd times when sync'ing PIR
x86/irq: KVM: Track PIR bitmap as an "unsigned long" array
KVM: VMX: Process PIR using 64-bit accesses on 64-bit kernels
KVM: VMX: Isolate pure loads from atomic XCHG when processing PIR
KVM: VMX: Use arch_xchg() when processing PIR to avoid instrumentation
x86/irq: KVM: Add helper for harvesting PIR to deduplicate KVM and
posted MSIs

arch/x86/include/asm/posted_intr.h | 79 +++++++++++++++++++++++++++---
arch/x86/kernel/irq.c | 63 ++++--------------------
arch/x86/kvm/lapic.c | 20 ++++----
arch/x86/kvm/lapic.h | 4 +-
arch/x86/kvm/vmx/posted_intr.h | 2 +-
5 files changed, 96 insertions(+), 72 deletions(-)


base-commit: c9ea48bb6ee6b28bbc956c1e8af98044618fed5e
--
2.49.0.rc1.451.g8f38331e32-goog