[PATCH 0/2] x86/entry: simplify RESTORE_CR3

[Lai Jiangshan]

When I searched percpu data touched by entry code for #DB
protection[1], it seems to me RESTORE_CR3() does too much work,
this patchset simplifies it.

Patch 1 enhances 21e944591102("x86/mm: Optimize RESTORE_CR3") for
kernel CR3.

Patch 2 *reverts* 21e944591102("x86/mm: Optimize RESTORE_CR3") for
User CR3.

Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Link: https://lore.kernel.org/lkml/20200525145102.122557-1-laijs@xxxxxxxxxxxxxxxxx
Lai Jiangshan (2):
  x86/entry: Don't write to CR3 when restoring to kernel CR3
  x86/entry: always flush user CR3 in RESTORE_CR3

 arch/x86/entry/calling.h  | 36 ++++++++----------------------------
 arch/x86/entry/entry_64.S |  6 +++---
 2 files changed, 11 insertions(+), 31 deletions(-)

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2.20.1