linux-kernel - Re: [PATCH v2 0/2] KVM: x86/mmu: Zap orphaned kids for nested TDP MMU

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Message-ID: <CANgfPd8vsgdduEfWLaQSyJkAD1zMgDmGJM+wbCyAXM2zq=rtSg@mail.gmail.com>
Date:   Wed, 12 Aug 2020 14:15:34 -0700
From:   Ben Gardon <bgardon@...gle.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Peter Shier <pshier@...gle.com>
Subject: Re: [PATCH v2 0/2] KVM: x86/mmu: Zap orphaned kids for nested TDP MMU

On Wed, Aug 12, 2020 at 12:28 PM Sean Christopherson
<sean.j.christopherson@...el.com> wrote:
>
> As promised, albeit a few days late.
>
> Ben, I kept your performance numbers even though it this version has
> non-trivial differences relative to what you tested.  I assume we'll need
> a v3 anyways if this doesn't provide the advertised performance benefits.
>
> Ben Gardon (1):
>   KVM: x86/MMU: Recursively zap nested TDP SPs when zapping last/only
>     parent
>
> Sean Christopherson (1):
>   KVM: x86/mmu: Move flush logic from mmu_page_zap_pte() to
>     FNAME(invlpg)
>
>  arch/x86/kvm/mmu/mmu.c         | 38 ++++++++++++++++++++++------------
>  arch/x86/kvm/mmu/paging_tmpl.h |  7 +++++--
>  2 files changed, 30 insertions(+), 15 deletions(-)
>

Thanks for sending this revised series Sean. This all looks good to me.
I think the main performance difference between this series and the
original patch I sent is only zapping nested TDP shadow pages, but I
expect it to behave more or less the same since the number of direct
TDP pages is pretty bounded.

>
> --
> 2.28.0
>