From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD2D3C433FE for ; Tue, 31 May 2022 19:15:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DE02D6B0071; Tue, 31 May 2022 15:15:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D67986B0073; Tue, 31 May 2022 15:15:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C05CE6B0074; Tue, 31 May 2022 15:15:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 3E08F6B0071 for ; Tue, 31 May 2022 15:15:16 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id 1233D80553 for ; Tue, 31 May 2022 19:15:16 +0000 (UTC) X-FDA: 79526991432.18.71E7EED Received: from mail-pf1-f175.google.com (mail-pf1-f175.google.com [209.85.210.175]) by imf25.hostedemail.com (Postfix) with ESMTP id ED499A0066 for ; Tue, 31 May 2022 19:14:40 +0000 (UTC) Received: by mail-pf1-f175.google.com with SMTP id y189so14045056pfy.10 for ; Tue, 31 May 2022 12:15:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=9LEQ/FAYXiOycH5Pgki0a9z4cyO6Zt9xfMoijJMruHE=; b=aoYECPuBKU7Lwlucej90ckQ541ZhjI9tXfhwwrKcylKXIDWfCbS506NUkmQoPpFtjp SxY2BDwXcLrnVWuj1tlKZZFXX3boTF7L4/UbiNTvLgRbtbDkTU4iJj5rlChLdWN+AXW9 /8uU6E9xZwRmy7lGao0XRqc/MNAqTYJl5P/hqXTOYZPGOYjzn/bAAgwSrZzoRfJDN/cT SuEfeHBBPefKlsfPtsSVZxWgXtnCDoM36KPdTqy2nZJEgrImggnACjHpxleCCtC3++o9 yxDwtO9/7vBZwXZmJ1VhyZ/Ls48fokKREiBfE3hRzy/o9DlM+JugKxkM4Tz9Yq/hcS03 4NUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=9LEQ/FAYXiOycH5Pgki0a9z4cyO6Zt9xfMoijJMruHE=; b=150Fr//Phir/KUy5rwyJ/WjYgvpDbhV1DXaLKQouTrM37wpmMLkOqqql6j1KUS7NhZ EZhHMi/k7xRjokMEjYVieSZU27bExQCoqmBj5doZo197BnJ4s4+rDtPDMXIUspQvXUHW dfE+UPojquynFp6DQTmZxH+yvF3yffohAY6ZBV6RA5ZDMTS4a5cijdAwHGuD7YpRUSPJ LxXMAnGCovRDlZNWFNXFIkEUh30h/CJhl2FXFCQ8tZIY0wepshGXH3dYKsLFgp/swPlv 1IDkr1ZvK+Ds9vJbVzyd10K4/cfV7eo+iLVrv1DOvjyA9ODPd5Nnmp+zT+U41G1dUOnq ne3w== X-Gm-Message-State: AOAM531hjGNZbg3hIU1HviPyxZ+Ov7um0HVF9oLg7DSn4a6YW9vHUnWt MiFPIGlq0E85sutgUegTuppZC9uj7vOd/vcRc2Etfw== X-Google-Smtp-Source: ABdhPJxAPLjjLuJnMkOUKZFNo6VjJcW6gX615tv0A0PeV8j4hPGz6HEz6HuE5g9ZfRLMUWFpXLfK3l0Q4MwhwgPaQrE= X-Received: by 2002:a63:2ad6:0:b0:3f9:d9fa:2713 with SMTP id q205-20020a632ad6000000b003f9d9fa2713mr44449690pgq.512.1654024511581; Tue, 31 May 2022 12:15:11 -0700 (PDT) MIME-Version: 1.0 References: <20220519153713.819591-1-chao.p.peng@linux.intel.com> <20220519153713.819591-4-chao.p.peng@linux.intel.com> In-Reply-To: <20220519153713.819591-4-chao.p.peng@linux.intel.com> From: Vishal Annapurve Date: Tue, 31 May 2022 12:15:00 -0700 Message-ID: Subject: Re: [PATCH v6 3/8] mm/memfd: Introduce MFD_INACCESSIBLE flag To: Chao Peng Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Yu Zhang , "Kirill A . Shutemov" , Andy Lutomirski , Jun Nakajima , dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , Michael Roth , mhocko@suse.com Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=aoYECPuB; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf25.hostedemail.com: domain of vannapurve@google.com designates 209.85.210.175 as permitted sender) smtp.mailfrom=vannapurve@google.com X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: ED499A0066 X-Rspam-User: X-Stat-Signature: 1rg6d6ni8r94jyrtqi9ppjis3tqa4j5q X-HE-Tag: 1654024480-750508 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, May 19, 2022 at 8:41 AM Chao Peng 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