From abf0878ce95f8a9b47d8ecf2de1d4617bec21711 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Wed, 25 May 2022 12:23:56 +1000 Subject: [PATCH] powerpc/64s: POWER10 nest MMU does not require flush escalation workaround Per (non-public) Nest MMU Workbook, POWER10 and POWER9P NMMU does not cache PTEs in PWC, so does not require PWC flush to invalidate these translations. Skip the workaround on POWER10 and later. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220525022358.780745-2-npiggin@gmail.com --- arch/powerpc/mm/book3s64/radix_tlb.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c index dda51fef2d2e..4e29b619578c 100644 --- a/arch/powerpc/mm/book3s64/radix_tlb.c +++ b/arch/powerpc/mm/book3s64/radix_tlb.c @@ -755,10 +755,18 @@ EXPORT_SYMBOL(radix__local_flush_tlb_page); static bool mm_needs_flush_escalation(struct mm_struct *mm) { /* - * P9 nest MMU has issues with the page walk cache - * caching PTEs and not flushing them properly when - * RIC = 0 for a PID/LPID invalidate + * The P9 nest MMU has issues with the page walk cache caching PTEs + * and not flushing them when RIC = 0 for a PID/LPID invalidate. + * + * This may have been fixed in shipping firmware (by disabling PWC + * or preventing it from caching PTEs), but until that is confirmed, + * this workaround is required - escalate all RIC=0 IS=1/2/3 flushes + * to RIC=2. + * + * POWER10 (and P9P) does not have this problem. */ + if (cpu_has_feature(CPU_FTR_ARCH_31)) + return false; if (atomic_read(&mm->context.copros) > 0) return true; return false;