Merge patch series "riscv: asid: switch to alternative way to fix stale TLB entries"

Merge patch series "riscv: asid: switch to alternative way to fix stale TLB entries"

Sergey Matyukevich <geomatsi@gmail.com> says:

Some time ago two different patches have been posted to fix stale TLB
entries that caused applications crashes.

The patch [0] suggested 'aggregating' mm_cpumask, i.e. current cpu is not
cleared for the switched-out task in switch_mm function. For additional
explanations see the commit message by Guo Ren. The same approach is
used by arc architecture, so another good comment is for switch_mm
in arch/arc/include/asm/mmu_context.h.

The patch [1] attempted to reduce the number of TLB flushes by deferring
(and possibly avoiding) them for CPUs not running the task.

Patch [1] has been merged. However we already have two bug reports from
different vendors. So apparently something is missing in the approach
suggested in [1]. In both cases the patch [0] fixed the issue.

This patch series reverts [1] and replaces it by [0].

[0] https://lore.kernel.org/linux-riscv/20221111075902.798571-1-guoren@kernel.org/
[1] https://lore.kernel.org/linux-riscv/20220829205219.283543-1-geomatsi@gmail.com/

* b4-shazam-merge:
  riscv: asid: Fixup stale TLB entry cause application crash
  Revert "riscv: mm: notify remote harts about mmu cache updates"

Link: https://lore.kernel.org/r/20230226150137.1919750-1-geomatsi@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>