linux-kernel - Re: [RFC PATCH V3 2/4] KVM: X86: Introduce role.glevel for level expanded pagetable

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: <e549d4c4-ca56-da1d-cc50-1a73621ba487@redhat.com>
Date:   Wed, 13 Apr 2022 18:03:51 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Lai Jiangshan <jiangshanlai@...il.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Lai Jiangshan <jiangshan.ljs@...group.com>,
        Jonathan Corbet <corbet@....net>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        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,
        "H. Peter Anvin" <hpa@...or.com>, linux-doc@...r.kernel.org
Subject: Re: [RFC PATCH V3 2/4] KVM: X86: Introduce role.glevel for level
 expanded pagetable

On 4/13/22 17:32, Sean Christopherson wrote:
>>> Are we planning on removing direct?
>>
>> I think so, it's redundant and the code almost always checks
>> direct||passthrough (which would be passthrough_delta > 0 with your scheme).
> 
> I'm ok dropping direct and rolling it into target_level, just so long as we add
> helpers, e.g. IIUC they would be
> 
> static inline bool is_sp_direct(...)
> {
> 	return !sp->role.target_level;
> }
> 
> static inline bool is_sp_direct_or_passthrough(...)
> {
> 	return sp->role.target_level != sp->role.level;
> }

Yes of course.  Or respectively:

	return sp->role.passthrough_levels == s->role.level;

	return sp->role.passthrough_levels > 0;

I'm not sure about a more concise name for the latter.  Maybe 
sp_has_gpt(...) but I haven't thought it through very much.

>>> Hmm, it's not a raw level though.
>>
>> Hence the plural. :)
> 
> LOL, I honestly thought that was a typo.  Making it plural sounds like it's passing
> through to multiple levels.

I meant it as number of levels being passed through.  I'll leave that to 
Jiangshan, either target_level or passthrough_levels will do for me.

Paolo