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Subject: Re: [PATCH v2 10/13] KVM: x86/mmu: Allow zapping collapsible SPTEs to
 use MMU read lock
To:     Ben Gardon <bgardon@google.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc:     Peter Xu <peterx@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Peter Shier <pshier@google.com>,
        Peter Feiner <pfeiner@google.com>,
        Junaid Shahid <junaids@google.com>,
        Jim Mattson <jmattson@google.com>,
        Yulei Zhang <yulei.kernel@gmail.com>,
        Wanpeng Li <kernellwp@gmail.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Xiao Guangrong <xiaoguangrong.eric@gmail.com>
References: <20210401233736.638171-1-bgardon@google.com>
 <20210401233736.638171-11-bgardon@google.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <4140362f-92d5-5c5e-de8e-4e1e3a65b317@redhat.com>
Date:   Fri, 2 Apr 2021 13:14:47 +0200
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On 02/04/21 01:37, Ben Gardon wrote:
> To speed the process of disabling dirty logging, change the TDP MMU
> function which zaps collapsible SPTEs to run under the MMU read lock.

Technically it only reduces the impact on the running VM; it doesn't
speed it up right?  Something like:

     To reduce the impact of disabling dirty logging, change the TDP MMU
     function which zaps collapsible SPTEs to run under the MMU read lock.
     This way, page faults on zapped SPTEs can proceed in parallel with
     kvm_mmu_zap_collapsible_sptes.

Paolo