linux-kernel - Re: [PATCHv6 11/30] x86/tdx: Handle in-kernel MMIO

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: <b1c1c4f1-8e5d-3c5a-8433-e101bbf79600@intel.com>
Date:   Wed, 16 Mar 2022 14:53:10 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        luto@...nel.org, peterz@...radead.org
Cc:     sathyanarayanan.kuppuswamy@...ux.intel.com, aarcange@...hat.com,
        ak@...ux.intel.com, dan.j.williams@...el.com, david@...hat.com,
        hpa@...or.com, jgross@...e.com, jmattson@...gle.com,
        joro@...tes.org, jpoimboe@...hat.com, knsathya@...nel.org,
        pbonzini@...hat.com, sdeep@...are.com, seanjc@...gle.com,
        tony.luck@...el.com, vkuznets@...hat.com, wanpengli@...cent.com,
        thomas.lendacky@....com, brijesh.singh@....com, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCHv6 11/30] x86/tdx: Handle in-kernel MMIO

On 3/15/22 19:08, Kirill A. Shutemov wrote:
> In other words, even if all of the work was done to paravirtualize all
> x86 MMIO users and virtio, this approach would still be needed. There
> is essentially no way to get rid of this code.
...
> == Patching TDX drivers ==
...> This approach will be adopted in the future, removing the bulk of
> MMIO #VEs. The #VE-based MMIO will remain serving non-virtio use cases.

I still don't like this very much, but I can't argue with my own logic. :)

BTW, TDX folks...  I expect you to, today, start coming up with a
comprehensive list of the MMIO-induced #VE's and the reasoning why they
should or should not be paravirtualized.  You're going to get grumpy
maintainers if this is done haphazardly as one-offs when users hit
performance issues.

Reviewed-by: Dave Hansen <dave.hansen@...ux.intel.com>