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Subject: Re: [PATCH v19 6/8] PM: hibernate: disable when there are active
 secretmem users
To:     Mark Rutland <mark.rutland@arm.com>,
        Mike Rapoport <rppt@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Andy Lutomirski <luto@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Christopher Lameter <cl@linux.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Elena Reshetova <elena.reshetova@intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Hagen Paul Pfeifer <hagen@jauu.net>,
        Ingo Molnar <mingo@redhat.com>,
        James Bottomley <jejb@linux.ibm.com>,
        Kees Cook <keescook@chromium.org>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        Matthew Wilcox <willy@infradead.org>,
        Matthew Garrett <mjg59@srcf.ucam.org>,
        Michal Hocko <mhocko@suse.com>,
        Mike Rapoport <rppt@linux.ibm.com>,
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        Palmer Dabbelt <palmer@dabbelt.com>,
        Palmer Dabbelt <palmerdabbelt@google.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
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        Yury Norov <yury.norov@gmail.com>, linux-api@vger.kernel.org,
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 <20210513184734.29317-7-rppt@kernel.org>
 <20210518102424.GD82842@C02TD0UTHF1T.local>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Message-ID: <47d0e5b1-ffee-d694-4865-8718619c1be0@redhat.com>
Date:   Tue, 18 May 2021 12:27:13 +0200
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On 18.05.21 12:24, Mark Rutland wrote:
> On Thu, May 13, 2021 at 09:47:32PM +0300, Mike Rapoport wrote:
>> From: Mike Rapoport <rppt@linux.ibm.com>
>>
>> It is unsafe to allow saving of secretmem areas to the hibernation
>> snapshot as they would be visible after the resume and this essentially
>> will defeat the purpose of secret memory mappings.
>>
>> Prevent hibernation whenever there are active secret memory users.
> 
> Have we thought about how this is going to work in practice, e.g. on
> mobile systems? It seems to me that there are a variety of common
> applications which might want to use this which people don't expect to
> inhibit hibernate (e.g. authentication agents, web browsers).
> 
> Are we happy to say that any userspace application can incidentally
> inhibit hibernate?

It's worth noting that secretmem has to be explicitly enabled by the 
admin to even work.

-- 
Thanks,

David / dhildenb