From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Alexander Potapenko <glider@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
the arch/x86 maintainers <x86@kernel.org>,
Kostya Serebryany <kcc@google.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Taras Madan <tarasmadan@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
"H . J . Lu" <hjl.tools@gmail.com>,
Andi Kleen <ak@linux.intel.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHv5 00/13] Linear Address Masking enabling
Date: Wed, 20 Jul 2022 03:59:50 +0300 [thread overview]
Message-ID: <20220720005950.fonulr4kkwbh6kbz@black.fi.intel.com> (raw)
In-Reply-To: <CAG_fn=WR3s3UMh76+bibN0nUpZk9AS_M18=oxP+pc_vtqKt34A@mail.gmail.com>
On Mon, Jul 18, 2022 at 07:39:22PM +0200, Alexander Potapenko wrote:
> On Wed, Jul 13, 2022 at 1:13 AM Kirill A. Shutemov
> <kirill.shutemov@linux.intel.com> wrote:
> >
> > Linear Address Masking[1] (LAM) modifies the checking that is applied to
> > 64-bit linear addresses, allowing software to use of the untranslated
> > address bits for metadata.
> >
> > The patchset brings support for LAM for userspace addresses.
> >
> > LAM_U48 enabling is controversial since it competes for bits with
> > 5-level paging. Its enabling isolated into an optional last patch that
> > can be applied at maintainer's discretion.
>
> I believe having optional patches will put unnecessary burden on
> distro maintainers.
> Soon after landing U48 support other changes will start piling on top
> of it, and it will be impossible to maintain a kernel with this patch
> removed.
> It also won't make any difference for the upstream, where this patch
> will be always present.
>
> We'd better decide now whether we need U48 or not, and either keep it
> or delete it.
Dave, Andy, any position on this?
I wrote LAM_U48 support to prove that interface is flexible enough, but I
see why it can be a problem if a distro will pick them up ahead of
upstream.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2022-07-20 0:59 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-12 23:13 Kirill A. Shutemov
2022-07-12 23:13 ` [PATCHv5 01/13] x86/mm: Fix CR3_ADDR_MASK Kirill A. Shutemov
2022-07-21 13:10 ` Alexander Potapenko
2022-07-29 3:00 ` Hu, Robert
2022-07-12 23:13 ` [PATCHv5 02/13] x86: CPUID and CR3/CR4 flags for Linear Address Masking Kirill A. Shutemov
2022-07-21 13:10 ` Alexander Potapenko
2022-07-12 23:13 ` [PATCHv5 03/13] mm: Pass down mm_struct to untagged_addr() Kirill A. Shutemov
2022-07-21 13:12 ` Alexander Potapenko
2022-07-12 23:13 ` [PATCHv5 04/13] x86/mm: Handle LAM on context switch Kirill A. Shutemov
2022-07-12 23:13 ` [PATCHv5 05/13] x86/uaccess: Provide untagged_addr() and remove tags before address check Kirill A. Shutemov
2022-07-13 15:02 ` [PATCHv5.1 04/13] x86/mm: Handle LAM on context switch Kirill A. Shutemov
2022-07-20 8:57 ` Alexander Potapenko
2022-07-20 12:38 ` Kirill A. Shutemov
2022-07-21 13:13 ` Alexander Potapenko
2022-07-21 13:14 ` [PATCHv5 05/13] x86/uaccess: Provide untagged_addr() and remove tags before address check Alexander Potapenko
2022-07-12 23:13 ` [PATCHv5 06/13] x86/mm: Provide ARCH_GET_UNTAG_MASK and ARCH_ENABLE_TAGGED_ADDR Kirill A. Shutemov
2022-07-18 17:47 ` Alexander Potapenko
2022-07-20 0:57 ` Kirill A. Shutemov
2022-07-20 8:19 ` Alexander Potapenko
2022-07-20 12:47 ` Kirill A. Shutemov
2022-07-20 12:54 ` Alexander Potapenko
2022-07-12 23:13 ` [PATCHv5 07/13] x86: Expose untagging mask in /proc/$PID/arch_status Kirill A. Shutemov
2022-07-21 13:47 ` Alexander Potapenko
2022-07-12 23:13 ` [PATCHv5 08/13] selftests/x86/lam: Add malloc test cases for linear-address masking Kirill A. Shutemov
2022-07-12 23:13 ` [PATCHv5 09/13] selftests/x86/lam: Add mmap and SYSCALL " Kirill A. Shutemov
2022-07-12 23:13 ` [PATCHv5 10/13] selftests/x86/lam: Add io_uring " Kirill A. Shutemov
2022-07-12 23:13 ` [PATCHv5 11/13] selftests/x86/lam: Add inherit " Kirill A. Shutemov
2022-07-12 23:13 ` [PATCHv5 OPTIONAL 12/13] x86/mm: Extend LAM to support to LAM_U48 Kirill A. Shutemov
2022-07-12 23:13 ` [PATCHv5 OPTIONAL 13/13] selftests/x86/lam: Add tests cases for LAM_U48 Kirill A. Shutemov
2022-07-18 17:39 ` [PATCHv5 00/13] Linear Address Masking enabling Alexander Potapenko
2022-07-20 0:59 ` Kirill A. Shutemov [this message]
2022-07-21 13:09 ` Alexander Potapenko
2022-07-21 17:07 ` Dave Hansen
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