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From:   Vishal Annapurve <vannapurve@google.com>
Date:   Tue, 31 May 2022 12:15:00 -0700
Message-ID: <CAGtprH8EMsPMMoOEzjRu0SMVKT0RqmkLk=n+6uXkBA6-wiRtUA@mail.gmail.com>
Subject: Re: [PATCH v6 3/8] mm/memfd: Introduce MFD_INACCESSIBLE flag
To:     Chao Peng <chao.p.peng@linux.intel.com>
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On Thu, May 19, 2022 at 8:41 AM Chao Peng <chao.p.peng@linux.intel.com> wrote:
>
> Introduce a new memfd_create() flag indicating the content of the
> created memfd is inaccessible from userspace through ordinary MMU
> access (e.g., read/write/mmap). However, the file content can be
> accessed via a different mechanism (e.g. KVM MMU) indirectly.
>

SEV, TDX, pkvm and software-only VMs seem to have usecases to set up
initial guest boot memory with the needed blobs.
TDX already supports a KVM IOCTL to transfer contents to private
memory using the TDX module but rest of the implementations will need
to invent
a way to do this.

Is there a plan to support a common implementation for either allowing
initial write access from userspace to private fd or adding a KVM
IOCTL to transfer contents to such a file,
as part of this series through future revisions?

Regards,
Vishal