Re: [PATCH v2] MIPS: mm: tlb-r4k: Uniquify TLB entries on init

[Thomas Bogendoerfer]

On Sat, Jun 07, 2025 at 01:43:56PM +0100, Jiaxun Yang wrote:
> Hardware or bootloader will initialize TLB entries to any value, which
> may collide with kernel's UNIQUE_ENTRYHI value. On MIPS microAptiv/M5150
> family of cores this will trigger machine check exception and cause boot
> failure. On M5150 simulation this could happen 7 times out of 1000 boots.
> 
> Replace local_flush_tlb_all() with r4k_tlb_uniquify() which probes each
> TLB ENTRIHI unique value for collisions before it's written, and in case
> of collision try a different ASID.
> 
> Cc: stable@xxxxxxxxxx
> Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
> ---
> Changes in v2:
> - Cycle ASID instead of ENTRYHI index in case of collison.
> - Avoid int over flow UB (Maciej)
> - Link to v1: https://lore.kernel.org/r/20250605-tlb-fix-v1-1-4af496f17b2f@xxxxxxxxxxx
> ---
>  arch/mips/mm/tlb-r4k.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 55 insertions(+), 1 deletion(-)

applied to mips-next.

Thomas.

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