linux-kernel - Re: Rename restrictedmem => guardedmem? (was: Re: [PATCH v10 0/9] KVM: mm: fd-based approach for supporting KVM)

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Message-ID: <a7dcbf5f-8ccf-1078-4bde-6cd2ed883ae6@redhat.com>
Date:   Wed, 19 Apr 2023 17:27:20 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Chao Peng <chao.p.peng@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        "Maciej S . Szmigiero" <mail@...iej.szmigiero.name>,
        Vlastimil Babka <vbabka@...e.cz>,
        Vishal Annapurve <vannapurve@...gle.com>,
        Yu Zhang <yu.c.zhang@...ux.intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        dhildenb@...hat.com, Quentin Perret <qperret@...gle.com>,
        tabba@...gle.com, Michael Roth <michael.roth@....com>,
        wei.w.wang@...el.com, Mike Rapoport <rppt@...nel.org>,
        Liam Merwick <liam.merwick@...cle.com>,
        Isaku Yamahata <isaku.yamahata@...il.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Ackerley Tng <ackerleytng@...gle.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: Rename restrictedmem => guardedmem? (was: Re: [PATCH v10 0/9]
 KVM: mm: fd-based approach for supporting KVM)

On 19.04.23 17:17, Sean Christopherson wrote:
> On Wed, Apr 19, 2023, David Hildenbrand wrote:
>> On 19.04.23 02:47, Sean Christopherson wrote:
>>> On Tue, Apr 18, 2023, David Hildenbrand wrote:
>>>> "memfd_vm" / "vm_mem" would be sooo (feel free to add some more o's here)
>>>> much easier to get. It's a special fd to be used to back VM memory. Depending
>>>> on the VM type (encrypted/protected/whatever), restrictions might apply (not
>>>> able to mmap, not able to read/write ...). For example, there really is no
>>>> need to disallow mmap/read/write when using that memory to back a simple VM
>>>> where all we want to do is avoid user-space page tables.
>>>
>>> In seriousness, I do agree with Jason's very explicit objection[2] against naming
>>> a non-KVM uAPI "guest", or any variation thereof.
>>
>> While I agree, it's all better than the naming we use right now ...
>>
>>
>> Let me throw "tee_mem" / "memfd_tee" into the picture. That could eventually
>> catch what we want to have.
>>
>> Or "coco_mem" / "memfd_coco".
>>
>> Of course, both expect that people know the terminology (just like what "vm"
>> stands for), but it's IMHO significantly better than
>> restricted/guarded/opaque/whatsoever.
>>
>> Again, expresses what it's used for, not why it behaves in weird ways.
> 
> I don't want to explicitly tie this to trusted execution or confidential compute,
> as there is value in backing "normal" guests with memory that cannot be accessed
> by the host userspace without jumping through a few extra hoops, e.g. to add a
> layer of protection against data corruption due to host userspace bugs.

Nothing speaks against using tee_mem for the same purpose I guess. I 
like the sound of it after all. :)

-- 
Thanks,

David / dhildenb