kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-11-08 18:57:22 +00:00
Code Issues Releases Packages Activity

x86/kfence: fix booting on 32bit non-PAE systems

Browse source 
commit 16459fe7e0 upstream.

The original patch inverted the PTE unconditionally to avoid
L1TF-vulnerable PTEs, but Linux doesn't make this adjustment in 2-level
paging.

Adjust the logic to use the flip_protnone_guard() helper, which is a nop
on 2-level paging but inverts the address bits in all other paging modes.

This doesn't matter for the Xen aspect of the original change.  Linux no
longer supports running 32bit PV under Xen, and Xen doesn't support
running any 32bit PV guests without using PAE paging.

Link: https://lkml.kernel.org/r/20260126211046.2096622-1-andrew.cooper3@citrix.com
Fixes: b505f19445 ("x86/kfence: avoid writing L1TF-vulnerable PTEs")
Reported-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Closes: https://lore.kernel.org/lkml/CAKFNMokwjw68ubYQM9WkzOuH51wLznHpEOMSqtMoV1Rn9JV_gw@mail.gmail.com/
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jann Horn <jannh@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andrew Cooper 2026-01-26 21:10:46 +00:00 • committed by Greg Kroah-Hartman
commit 917ccf6fd1
1 changed files with 4 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files