Feedback-ID: ie3994620:Fastmail
Date:   Thu, 26 Jan 2023 17:42:06 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, x86@kernel.org,
        Kostya Serebryany <kcc@google.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Alexander Potapenko <glider@google.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>,
        Bharata B Rao <bharata@amd.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Ashok Raj <ashok.raj@intel.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCHv15 00/17] Linear Address Masking enabling
Message-ID: <20230126144206.mebmtx5ku3qy6xf6@box.shutemov.name>
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On Tue, Jan 24, 2023 at 02:01:58PM +0300, Kirill A. Shutemov wrote:
> On Mon, Jan 23, 2023 at 06:07:20PM -0800, Linus Torvalds wrote:
> > On Mon, Jan 23, 2023 at 2:05 PM 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 capability can be used for efficient address sanitizers (ASAN)
> > > implementation and for optimizations in JITs and virtual machines.
> > >
> > > The patchset brings support for LAM for userspace addresses. Only LAM_U57 at
> > > this time.
> > 
> > I didn't react to anything objectionable in the series.
> > 
> > My only reaction was actually to ask "when / what CPU cores are
> > expected to support this feature"?
> > 
> > Maybe it was mentioned somewhere, and I'm just blind and not finding
> > it.  But even the "Instruction Set Extensions and Future Features"
> > paper seems to just be talking about the CPUID bits, not about any
> > actual "this is when we expect it".
> 
> There's no announced CPUs that have the feature. And it is above my pay
> grade to disclose anything beyond that.

I've asked around and if everything goes well it will be available early
2024.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov