Commit 95acc9c2 authored by Yu Zhao's avatar Yu Zhao Committed by Todd Kjos
Browse files

FROMLIST: mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG

Some architectures support the accessed bit in non-leaf PMD entries,
e.g., x86 sets the accessed bit in a non-leaf PMD entry when using it
as part of linear address translation [1]. Page table walkers that
clear the accessed bit may use this capability to reduce their search
space.

Note that:
1. Although an inline function is preferable, this capability is added
   as a configuration option for consistency with the existing macros.
2. Due to the little interest in other varieties, this capability was
   only tested on Intel and AMD CPUs.

[1]: Intel 64 and IA-32 Architectures Software Developer's Manual
     Volume 3 (June 2021), section 4.8

Link: https://lore.kernel.org/r/20220309021230.721028-3-yuzhao@google.com/


Signed-off-by: default avatarYu Zhao <yuzhao@google.com>
Reviewed-by: default avatarBarry Song <baohua@kernel.org>
Acked-by: default avatarBrian Geffon <bgeffon@google.com>
Acked-by: default avatarJan Alexander Steffens (heftig) <heftig@archlinux.org>
Acked-by: default avatarOleksandr Natalenko <oleksandr@natalenko.name>
Acked-by: default avatarSteven Barrett <steven@liquorix.net>
Acked-by: default avatarSuleiman Souhlal <suleiman@google.com>
Tested-by: default avatarDaniel Byrne <djbyrne@mtu.edu>
Tested-by: default avatarDonald Carr <d@chaos-reins.com>
Tested-by: default avatarHolger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: default avatarKonstantin Kharlamov <Hi-Angel@yandex.ru>
Tested-by: default avatarShuang Zhai <szhai2@cs.rochester.edu>
Tested-by: default avatarSofia Trinh <sofia.trinh@edi.works>
Tested-by: default avatarVaibhav Jain <vaibhav@linux.ibm.com>
Bug: 227651406
Signed-off-by: default avatarKalesh Singh <kaleshsingh@google.com>
Change-Id: I73f84a21fd315192eaa3e6443334ed1bccb4e99e
parent 1ed19b56
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