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From: James Bottomley <jejb@linux.ibm.com>
To: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>,
	Mike Rapoport <rppt@kernel.org>,
	Mike Rapoport <rppt@linux.ibm.com>,
	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>, Ingo Molnar <mingo@redhat.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Matthew Wilcox <willy@infradead.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Roman Gushchin <guro@fb.com>, Shakeel Butt <shakeelb@google.com>,
	Shuah Khan <shuah@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tycho Andersen <tycho@tycho.ws>, Will Deacon <will@kernel.org>,
	linux-api@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org,
	x86@kernel.org, Hagen Paul Pfeifer <hagen@jauu.net>,
	Palmer Dabbelt <palmerdabbelt@google.com>
Subject: Re: [PATCH v17 07/10] mm: introduce memfd_secret system call to create "secret" memory areas
Date: Tue, 16 Feb 2021 08:25:39 -0800	[thread overview]
Message-ID: <12c3890b233c8ec8e3967352001a7b72a8e0bfd0.camel@linux.ibm.com> (raw)
In-Reply-To: <YCrJjYmr7A2nO6lA@dhcp22.suse.cz>

On Mon, 2021-02-15 at 20:20 +0100, Michal Hocko wrote:
[...]
> > >   What kind of flags are we talking about and why would that be a
> > > problem with memfd_create interface? Could you be more specific
> > > please?
> > 
> > You mean what were the ioctl flags in the patch series linked
> > above? They were SECRETMEM_EXCLUSIVE and SECRETMEM_UNCACHED in
> > patch 3/5. 
> 
> OK I see. How many potential modes are we talking about? A few or
> potentially many?
 
Well I initially thought there were two (uncached or not) until you
came up with the migratable or non-migratable, which affects the
security properties.  But now there's also potential for hardware
backing, like mktme,  described by flags as well.  I suppose you could
also use RDT to restrict which cache the data goes into: say L1 but not
L2 on to lessen the impact of fully uncached (although the big thrust
of uncached was to blunt hyperthread side channels).  So there is
potential for quite a large expansion even though I'd be willing to bet
that a lot of the modes people have thought about turn out not to be
very effective in the field.

James




  reply	other threads:[~2021-02-16 16:26 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-08  8:49 [PATCH v17 00/10] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2021-02-08  8:49 ` [PATCH v17 01/10] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
2021-02-08  8:49 ` [PATCH v17 02/10] mmap: make mlock_future_check() global Mike Rapoport
2021-02-08  8:49 ` [PATCH v17 03/10] riscv/Kconfig: make direct map manipulation options depend on MMU Mike Rapoport
2021-02-08  8:49 ` [PATCH v17 04/10] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
2021-02-08  8:49 ` [PATCH v17 05/10] set_memory: allow querying whether set_direct_map_*() is actually enabled Mike Rapoport
2021-02-08  8:49 ` [PATCH v17 06/10] arm64: kfence: fix header inclusion Mike Rapoport
2021-02-08  8:49 ` [PATCH v17 07/10] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2021-02-08 10:49   ` Michal Hocko
2021-02-08 21:26     ` Mike Rapoport
2021-02-09  8:47       ` Michal Hocko
2021-02-09  9:09         ` Mike Rapoport
2021-02-09 13:17           ` Michal Hocko
2021-02-11  7:13             ` Mike Rapoport
2021-02-11  8:39               ` Michal Hocko
2021-02-11  9:01                 ` David Hildenbrand
2021-02-11  9:38                   ` Michal Hocko
2021-02-11  9:48                     ` David Hildenbrand
2021-02-11 10:02                     ` David Hildenbrand
2021-02-11 11:29                       ` Mike Rapoport
2021-02-11 11:27                   ` Mike Rapoport
2021-02-11 12:07                     ` David Hildenbrand
2021-02-11 23:09                       ` Mike Rapoport
2021-02-12  9:18                         ` David Hildenbrand
2021-02-14  9:19                           ` Mike Rapoport
2021-02-14  9:58                             ` David Hildenbrand
2021-02-14 19:21                               ` James Bottomley
2021-02-15  9:13                                 ` Michal Hocko
2021-02-15 18:14                                   ` James Bottomley
2021-02-15 19:20                                     ` Michal Hocko
2021-02-16 16:25                                       ` James Bottomley [this message]
2021-02-16 16:34                                         ` David Hildenbrand
2021-02-16 16:44                                           ` James Bottomley
2021-02-16 17:16                                             ` David Hildenbrand
2021-02-17 16:19                                               ` James Bottomley
2021-02-22  9:38                                                 ` David Hildenbrand
2021-02-22 10:50                                                   ` David Hildenbrand
2021-02-16 16:51                                         ` Michal Hocko
2021-02-11 11:20                 ` Mike Rapoport
2021-02-11 12:30                   ` Michal Hocko
2021-02-11 22:59                     ` Mike Rapoport
2021-02-12  9:02                       ` Michal Hocko
2021-02-08  8:49 ` [PATCH v17 08/10] PM: hibernate: disable when there are active secretmem users Mike Rapoport
2021-02-08 10:18   ` Michal Hocko
2021-02-08 10:32     ` David Hildenbrand
2021-02-08 10:51       ` Michal Hocko
2021-02-08 10:53         ` David Hildenbrand
2021-02-08 10:57           ` Michal Hocko
2021-02-08 11:13             ` David Hildenbrand
2021-02-08 11:14               ` David Hildenbrand
2021-02-08 11:26                 ` David Hildenbrand
2021-02-08 12:17                   ` Michal Hocko
2021-02-08 13:34                     ` Michal Hocko
2021-02-08 13:40                     ` David Hildenbrand
2021-02-08 21:28     ` Mike Rapoport
2021-02-22  7:34   ` Matthew Garrett
2021-02-22 10:23     ` Mike Rapoport
2021-02-22 18:27       ` Matthew Garrett
2021-02-22 19:17       ` Dan Williams
2021-02-22 19:21         ` James Bottomley
2021-02-08  8:49 ` [PATCH v17 09/10] arch, mm: wire up memfd_secret system call where relevant Mike Rapoport
2021-02-08  8:49 ` [PATCH v17 10/10] secretmem: test: add basic selftest for memfd_secret(2) Mike Rapoport
2021-02-08  9:27 ` [PATCH v17 00/10] mm: introduce memfd_secret system call to create "secret" memory areas David Hildenbrand
2021-02-08 21:13   ` Mike Rapoport
2021-02-08 21:38     ` David Hildenbrand
2021-02-09  8:59       ` Michal Hocko
2021-02-09  9:15         ` David Hildenbrand
2021-02-09  9:53           ` Michal Hocko
2021-02-09 10:23             ` David Hildenbrand
2021-02-09 10:30               ` David Hildenbrand
2021-02-09 13:25               ` Michal Hocko
2021-02-09 16:17                 ` David Hildenbrand
2021-02-09 20:08                   ` Michal Hocko

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