linux-kernel - Re: [PATCH 03/22] kvm: mmu: Init / Uninit the TDP MMU

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2633cc07-f106-25ba-0ab9-d4a422aca171@redhat.com>
Date:   Wed, 30 Sep 2020 19:39:38 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Ben Gardon <bgardon@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Cannon Matthews <cannonmatthews@...gle.com>,
        Peter Xu <peterx@...hat.com>, Peter Shier <pshier@...gle.com>,
        Peter Feiner <pfeiner@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>
Subject: Re: [PATCH 03/22] kvm: mmu: Init / Uninit the TDP MMU

On 30/09/20 18:57, Sean Christopherson wrote:
>> +
>> +static bool __read_mostly tdp_mmu_enabled = true;
>> +module_param_named(tdp_mmu, tdp_mmu_enabled, bool, 0644);
> This param should not exist until the TDP MMU is fully functional, e.g. running
> KVM against "kvm: mmu: Support zapping SPTEs in the TDP MMU" immediately hits a
> BUG() in the rmap code.  I haven't wrapped my head around the entire series to
> grok whether it make sense to incrementally enable the TDP MMU, but my gut says
> that's probably non-sensical.

No, it doesn't.  Whether to add the module parameter is kind of
secondary, but I agree it shouldn't be true---not even at the end of
this series, since fast page fault for example is not implemented yet.

Paolo