linux-kernel - Re: [PATCH v2 0/8] x86/irq: KVM: Optimize KVM's PIR harvesting

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Message-ID: <174562143766.1001424.10208731170484769772.b4-ty@google.com>
Date: Fri, 25 Apr 2025 16:11:00 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org, 
	Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH v2 0/8] x86/irq: KVM: Optimize KVM's PIR harvesting

On Tue, 01 Apr 2025 09:34:39 -0700, Sean Christopherson wrote:
> 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.
> 
> v2:
>  - Collect a review. [tglx]
>  - Use an "unsigned long" with a bitwise-OR to gather PIR. [tglx]
> 
> [...]

Applied to kvm-x86 pir.

Thomas and other x86 maintainers, please holler if you object to taking this
through KVM (x86), or to any of the patches.  I want to start getting coverage
in -next, and deliberately put this in its own topic branch so I can rewrite or
drop things as needed.

[1/8] x86/irq: Ensure initial PIR loads are performed exactly once
      https://github.com/kvm-x86/linux/commit/600e9606046a
[2/8] x86/irq: Track if IRQ was found in PIR during initial loop (to load PIR vals)
      https://github.com/kvm-x86/linux/commit/3cdb8261504c
[3/8] KVM: VMX: Ensure vIRR isn't reloaded at odd times when sync'ing PIR
      https://github.com/kvm-x86/linux/commit/6433fc01f9f1
[4/8] x86/irq: KVM: Track PIR bitmap as an "unsigned long" array
      https://github.com/kvm-x86/linux/commit/f1459315f4d2
[5/8] KVM: VMX: Process PIR using 64-bit accesses on 64-bit kernels
      https://github.com/kvm-x86/linux/commit/06b4d0ea226c
[6/8] KVM: VMX: Isolate pure loads from atomic XCHG when processing PIR
      https://github.com/kvm-x86/linux/commit/b41f8638b9d3
[7/8] KVM: VMX: Use arch_xchg() when processing PIR to avoid instrumentation
      https://github.com/kvm-x86/linux/commit/baf68a0e3bd6
[8/8] x86/irq: KVM: Add helper for harvesting PIR to deduplicate KVM and posted MSIs
      https://github.com/kvm-x86/linux/commit/edaf3eded386

--
https://github.com/kvm-x86/linux/tree/next