linux-kernel - Re: [PATCH v9 00/11] KVM: x86/mmu: Age sptes locklessly

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Message-ID: <173958060314.1192011.10710541316458092620.b4-ty@google.com>
Date: Fri, 14 Feb 2025 16:50:24 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	James Houghton <jthoughton@...gle.com>
Cc: David Matlack <dmatlack@...gle.com>, David Rientjes <rientjes@...gle.com>, 
	Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, Wei Xu <weixugc@...gle.com>, 
	Yu Zhao <yuzhao@...gle.com>, Axel Rasmussen <axelrasmussen@...gle.com>, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 00/11] KVM: x86/mmu: Age sptes locklessly

On Tue, 04 Feb 2025 00:40:27 +0000, James Houghton wrote:
> By aging sptes locklessly with the TDP MMU and the shadow MMU, neither
> vCPUs nor reclaim (mmu_notifier_invalidate_range*) will get stuck
> waiting for aging. This contention reduction improves guest performance
> and saves a significant amount of Google Cloud's CPU usage, and it has
> valuable improvements for ChromeOS, as Yu has mentioned previously[1].
> 
> Please see v8[8] for some performance results using
> access_tracking_perf_test patched to use MGLRU.
> 
> [...]

Applied to kvm-x86 mmu, thanks!

[01/11] KVM: Rename kvm_handle_hva_range()
        https://github.com/kvm-x86/linux/commit/374ccd63600b
[02/11] KVM: Add lockless memslot walk to KVM
        https://github.com/kvm-x86/linux/commit/aa34b811650c
[03/11] KVM: x86/mmu: Factor out spte atomic bit clearing routine
        https://github.com/kvm-x86/linux/commit/e29b74920e6f
[04/11] KVM: x86/mmu: Relax locking for kvm_test_age_gfn() and kvm_age_gfn()
        https://github.com/kvm-x86/linux/commit/b146a9b34aed
[05/11] KVM: x86/mmu: Rename spte_has_volatile_bits() to spte_needs_atomic_write()
        https://github.com/kvm-x86/linux/commit/61d65f2dc766
[06/11] KVM: x86/mmu: Skip shadow MMU test_young if TDP MMU reports page as young
        https://github.com/kvm-x86/linux/commit/e25c2332346f
[07/11] KVM: x86/mmu: Only check gfn age in shadow MMU if indirect_shadow_pages > 0
        https://github.com/kvm-x86/linux/commit/8c403cf23119
[08/11] KVM: x86/mmu: Refactor low level rmap helpers to prep for walking w/o mmu_lock
        https://github.com/kvm-x86/linux/commit/9fb13ba6b5ff
[09/11] KVM: x86/mmu: Add infrastructure to allow walking rmaps outside of mmu_lock
        https://github.com/kvm-x86/linux/commit/4834eaded91e
[10/11] KVM: x86/mmu: Add support for lockless walks of rmap SPTEs
        https://github.com/kvm-x86/linux/commit/bb6c7749ccee
[11/11] KVM: x86/mmu: Support rmap walks without holding mmu_lock when aging gfns
        https://github.com/kvm-x86/linux/commit/af3b6a9eba48

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