From: Peter Zijlstra <peterz@infradead.org>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
x86@kernel.org, Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@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-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFCv2 07/10] x86/mm: Handle tagged memory accesses from kernel threads
Date: Wed, 11 May 2022 09:23:10 +0200 [thread overview]
Message-ID: <20220511072310.GU76023@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20220511022751.65540-9-kirill.shutemov@linux.intel.com>
On Wed, May 11, 2022 at 05:27:48AM +0300, Kirill A. Shutemov wrote:
> When a kernel thread performs memory access on behalf of a process (like
> in async I/O, io_uring, etc.) it has to respect tagging setup of the
> process as user addresses can include tags.
>
> Normally, LAM setup is per-thread and recorded in thread features, but
> for this use case kernel also tracks LAM setup per-mm. mm->context.lam
> would record LAM that allows the most tag bits among the threads of
> the mm.
Then why does it *ever* make sense to track it per thread? It's not like
it makes heaps of sense to allow one thread in a process to use LAM but
not the others.
next prev parent reply other threads:[~2022-05-11 7:23 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-11 2:27 [RFCv2 00/10] Linear Address Masking enabling Kirill A. Shutemov
2022-05-11 2:27 ` [PATCH] x86: Implement Linear Address Masking support Kirill A. Shutemov
2022-05-12 13:01 ` David Laight
2022-05-12 14:07 ` Matthew Wilcox
2022-05-12 15:06 ` Thomas Gleixner
2022-05-12 15:33 ` David Laight
2022-05-12 14:35 ` Peter Zijlstra
2022-05-12 17:00 ` Kirill A. Shutemov
2022-05-11 2:27 ` [RFCv2 01/10] x86/mm: Fix CR3_ADDR_MASK Kirill A. Shutemov
2022-05-11 2:27 ` [RFCv2 02/10] x86: CPUID and CR3/CR4 flags for Linear Address Masking Kirill A. Shutemov
2022-05-11 2:27 ` [RFCv2 03/10] x86: Introduce userspace API to handle per-thread features Kirill A. Shutemov
2022-05-12 12:02 ` Thomas Gleixner
2022-05-12 12:04 ` [PATCH] x86/prctl: Remove pointless task argument Thomas Gleixner
2022-05-13 12:30 ` [tip: x86/cleanups] " tip-bot2 for Thomas Gleixner
2022-05-13 14:09 ` [RFCv2 03/10] x86: Introduce userspace API to handle per-thread features Alexander Potapenko
2022-05-13 17:34 ` Edgecombe, Rick P
2022-05-13 23:09 ` Kirill A. Shutemov
2022-05-13 23:50 ` Edgecombe, Rick P
2022-05-14 8:37 ` Thomas Gleixner
2022-05-14 23:06 ` Edgecombe, Rick P
2022-05-15 9:02 ` Thomas Gleixner
2022-05-15 18:24 ` Edgecombe, Rick P
2022-05-15 19:38 ` Thomas Gleixner
2022-05-15 22:01 ` Edgecombe, Rick P
2022-05-11 2:27 ` [RFCv2 04/10] x86/mm: Introduce X86_THREAD_LAM_U48 and X86_THREAD_LAM_U57 Kirill A. Shutemov
2022-05-11 7:02 ` Peter Zijlstra
2022-05-12 12:24 ` Thomas Gleixner
2022-05-12 14:37 ` Peter Zijlstra
2022-05-11 2:27 ` [RFCv2 05/10] x86/mm: Provide untagged_addr() helper Kirill A. Shutemov
2022-05-11 7:21 ` Peter Zijlstra
2022-05-11 7:45 ` Peter Zijlstra
2022-05-12 13:06 ` Thomas Gleixner
2022-05-12 14:23 ` Peter Zijlstra
2022-05-12 15:16 ` Thomas Gleixner
2022-05-12 23:14 ` Thomas Gleixner
2022-05-13 10:14 ` David Laight
2022-05-11 2:27 ` [RFCv2 06/10] x86/uaccess: Remove tags from the address before checking Kirill A. Shutemov
2022-05-12 13:02 ` David Laight
2022-05-11 2:27 ` [RFCv2 07/10] x86/mm: Handle tagged memory accesses from kernel threads Kirill A. Shutemov
2022-05-11 7:23 ` Peter Zijlstra [this message]
2022-05-12 13:30 ` Thomas Gleixner
2022-05-11 2:27 ` [RFCv2 08/10] x86/mm: Make LAM_U48 and mappings above 47-bits mutually exclusive Kirill A. Shutemov
2022-05-12 13:36 ` Thomas Gleixner
2022-05-13 23:22 ` Kirill A. Shutemov
2022-05-14 8:37 ` Thomas Gleixner
2022-05-18 8:43 ` Bharata B Rao
2022-05-18 17:08 ` Kirill A. Shutemov
2022-05-11 2:27 ` [RFCv2 09/10] x86/mm: Add userspace API to enable Linear Address Masking Kirill A. Shutemov
2022-05-11 7:26 ` Peter Zijlstra
2022-05-12 14:46 ` Thomas Gleixner
2022-05-11 14:15 ` H.J. Lu
2022-05-12 14:21 ` Thomas Gleixner
2022-05-11 2:27 ` [RFCv2 10/10] x86: Expose thread features status in /proc/$PID/arch_status Kirill A. Shutemov
2022-05-11 6:49 ` [RFCv2 00/10] Linear Address Masking enabling Peter Zijlstra
2022-05-12 15:42 ` Thomas Gleixner
2022-05-12 16:56 ` Kirill A. Shutemov
2022-05-12 19:31 ` Thomas Gleixner
2022-05-12 23:21 ` Thomas Gleixner
2022-05-12 17:22 ` Dave Hansen
2022-05-12 19:39 ` Thomas Gleixner
2022-05-12 21:24 ` Thomas Gleixner
2022-05-13 14:43 ` Matthew Wilcox
2022-05-13 22:59 ` Kirill A. Shutemov
2022-05-12 21:51 ` Dave Hansen
2022-05-12 22:10 ` H.J. Lu
2022-05-12 23:35 ` Thomas Gleixner
2022-05-13 0:08 ` H.J. Lu
2022-05-13 0:46 ` Dave Hansen
2022-05-13 1:27 ` Thomas Gleixner
2022-05-13 3:05 ` Dave Hansen
2022-05-13 8:28 ` Thomas Gleixner
2022-05-13 22:48 ` Kirill A. Shutemov
2022-05-13 9:14 ` Catalin Marinas
2022-05-13 9:26 ` Thomas Gleixner
2022-05-13 0:46 ` Thomas Gleixner
2022-05-13 11:07 ` Alexander Potapenko
2022-05-13 11:28 ` David Laight
2022-05-13 12:26 ` Alexander Potapenko
2022-05-13 14:26 ` David Laight
2022-05-13 15:28 ` Alexander Potapenko
2022-05-13 23:01 ` Kirill A. Shutemov
2022-05-14 10:00 ` Thomas Gleixner
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