linux-kernel - Re: [PATCH v10 0/9] mm: introduce memfd_secret system call to create "secret" memory areas

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Message-ID: <20201124092919.GI8537@kernel.org>
Date:   Tue, 24 Nov 2020 11:29:19 +0200
From:   Mike Rapoport <rppt@...nel.org>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Christopher Lameter <cl@...ux.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        David Hildenbrand <david@...hat.com>,
        Elena Reshetova <elena.reshetova@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        James Bottomley <jejb@...ux.ibm.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Matthew Wilcox <willy@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Roman Gushchin <guro@...com>, Shuah Khan <shuah@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tycho Andersen <tycho@...ho.ws>, Will Deacon <will@...nel.org>,
        Linux API <linux-api@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        linux-riscv@...ts.infradead.org, X86 ML <x86@...nel.org>
Subject: Re: [PATCH v10 0/9] mm: introduce memfd_secret system call to create
 "secret" memory areas

On Mon, Nov 23, 2020 at 07:28:22AM -0800, Andy Lutomirski wrote:
> On Mon, Nov 23, 2020 at 1:54 AM Mike Rapoport <rppt@...nel.org> wrote:
> >
> > From: Mike Rapoport <rppt@...ux.ibm.com>
> >
> > Hi,
> >
> > This is an implementation of "secret" mappings backed by a file descriptor.
> >
> > The file descriptor backing secret memory mappings is created using a
> > dedicated memfd_secret system call The desired protection mode for the
> > memory is configured using flags parameter of the system call. The mmap()
> > of the file descriptor created with memfd_secret() will create a "secret"
> > memory mapping. The pages in that mapping will be marked as not present in
> > the direct map and will have desired protection bits set in the user page
> > table. For instance, current implementation allows uncached mappings.
> 
> I'm still not ready to ACK uncached mappings on x86.  I'm fine with
> the concept of allowing privileged users to create UC memory on x86
> for testing and experimentation, but it's a big can of worms in
> general. 

Ok, let's move forward without UC. 

-- 
Sincerely yours,
Mike.