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x86/irq: KVM: Optimize KVM's PIR harvesting

From:  Sean Christopherson <seanjc-AT-google.com>
To:  Thomas Gleixner <tglx-AT-linutronix.de>, Ingo Molnar <mingo-AT-redhat.com>, Borislav Petkov <bp-AT-alien8.de>, Dave Hansen <dave.hansen-AT-linux.intel.com>, x86-AT-kernel.org, Sean Christopherson <seanjc-AT-google.com>, Paolo Bonzini <pbonzini-AT-redhat.com>
Subject:  [PATCH 0/8] x86/irq: KVM: Optimize KVM's PIR harvesting
Date:  Fri, 14 Mar 2025 20:06:21 -0700
Message-ID:  <20250315030630.2371712-1-seanjc@google.com>
Cc:  linux-kernel-AT-vger.kernel.org, kvm-AT-vger.kernel.org, Jacob Pan <jacob.jun.pan-AT-linux.intel.com>, Jim Mattson <jmattson-AT-google.com>
Archive-link:  Article

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




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