Date:   Tue, 23 Nov 2021 13:17:23 -0400
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     David Hildenbrand <david@redhat.com>,
        Chao Peng <chao.p.peng@linux.intel.com>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-fsdevel@vger.kernel.org, qemu-devel@nongnu.org,
        Jonathan Corbet <corbet@lwn.net>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
        Hugh Dickins <hughd@google.com>,
        Jeff Layton <jlayton@kernel.org>,
        "J . Bruce Fields" <bfields@fieldses.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        luto@kernel.org, john.ji@intel.com, susie.li@intel.com,
        jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com
Subject: Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST
Message-ID: <20211123171723.GD5112@ziepe.ca>
References: <20211119134739.20218-1-chao.p.peng@linux.intel.com>
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 <20211119151943.GH876299@ziepe.ca>
 <df11d753-6242-8f7c-cb04-c095f68b41fa@redhat.com>
 <6de78894-8269-ea3a-b4ee-a5cc4dad827e@redhat.com>
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On Tue, Nov 23, 2021 at 10:06:02AM +0100, Paolo Bonzini wrote:

> I think it's great that memfd hooks are usable by more than one subsystem,
> OTOH it's fair that whoever needs it does the work---and VFIO does not need
> it for confidential VMs, yet, so it should be fine for now to have a single
> user.

I think adding a new interface to a core kernel subsystem should come
with a greater requirement to work out something generally useful and
not be overly wedded to a single use case (eg F_SEAL_GUEST)

Especially if something like 'single user' is not just a small
implementation artifact but a key design tennant of the whole eventual
solution.

Jason