linux-kernel - Re: [PATCH 3/3] /dev/mem: Do not map unaccepted memory

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Message-ID: <20230907142510.vcj57cvnewqt4m37@box.shutemov.name>
Date:   Thu, 7 Sep 2023 17:25:10 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Borislav Petkov <bp@...en8.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Baoquan He <bhe@...hat.com>, Vivek Goyal <vgoyal@...hat.com>,
        Dave Young <dyoung@...hat.com>, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-coco@...ts.linux.dev, linux-efi@...r.kernel.org,
        kexec@...ts.infradead.org
Subject: Re: [PATCH 3/3] /dev/mem: Do not map unaccepted memory

On Thu, Sep 07, 2023 at 07:15:21AM -0700, Dave Hansen wrote:
> On 9/6/23 00:39, Adrian Hunter wrote:
> > Support for unaccepted memory was added recently, refer commit
> > dcdfdd40fa82 ("mm: Add support for unaccepted memory"), whereby
> > a virtual machine may need to accept memory before it can be used.
> > 
> > Do not map unaccepted memory because it can cause the guest to fail.
> 
> Doesn't /dev/mem already provide a billion ways for someone to shoot
> themselves in the foot?  TDX seems to have added the 1,000,000,001st.
> Is this really worth patching?

Is it better to let TD die silently? I don't think so.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov