linux-kernel - Re: [RFC] KVM: mm: fd-based approach for supporting KVM guest private memory

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: <cb3b2281-8651-672a-53e0-d0c7a9407643@intel.com>
Date:   Wed, 1 Sep 2021 12:26:07 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     jejb@...ux.ibm.com, Andy Lutomirski <luto@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        Sean Christopherson <seanjc@...gle.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 list <kvm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Borislav Petkov <bp@...en8.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Joerg Roedel <jroedel@...e.de>,
        Andi Kleen <ak@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Tom Lendacky <thomas.lendacky@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Varad Gautam <varad.gautam@...e.com>,
        Dario Faggioli <dfaggioli@...e.com>,
        the arch/x86 maintainers <x86@...nel.org>,
        linux-mm@...ck.org, linux-coco@...ts.linux.dev,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Yu Zhang <yu.c.zhang@...ux.intel.com>
Subject: Re: [RFC] KVM: mm: fd-based approach for supporting KVM guest private
 memory

On 9/1/21 9:18 AM, James Bottomley wrote:
>> So I think there are literally zero code paths that currently call
>> try_to_unmap() that will actually work like that on TDX.  If we run
>> out of memory on a TDX host, we can kill the guest completely and
>> reclaim all of its memory (which probably also involves killing QEMU
>> or whatever other user program is in charge), but that's really our
>> only option.
> I think our only option for swap is guest co-operation.

Yes, today that's the only choice.  Both TDX and SEV-SNP can
*theoretically* extend their architectures to enable swap with
uncooperative guests.  But, frankly, nobody has been asking for it.

If you care, please ask Intel and AMD to fix this gap.