Excerpts from Michael Ellerman's message of December 14, 2020 8:43 pm: > Nicholas Piggin <npig...@gmail.com> writes: >> Excerpts from Geert Uytterhoeven's message of December 10, 2020 7:06 pm: >>> Hi Nicholas, >>> >>> On Fri, Nov 20, 2020 at 4:01 AM Nicholas Piggin <npig...@gmail.com> wrote: >>>> >>>> When offlining a CPU, powerpc/64s does not flush TLBs, rather it just >>>> leaves the CPU set in mm_cpumasks, so it continues to receive TLBIEs >>>> to manage its TLBs. >>>> >>>> However the exit_flush_lazy_tlbs() function expects that after >>>> returning, all CPUs (except self) have flushed TLBs for that mm, in >>>> which case TLBIEL can be used for this flush. This breaks for offline >>>> CPUs because they don't get the IPI to flush their TLB. This can lead >>>> to stale translations. >>>> >>>> Fix this by clearing the CPU from mm_cpumasks, then flushing all TLBs >>>> before going offline. >>>> >>>> These offlined CPU bits stuck in the cpumask also prevents the cpumask >>>> from being trimmed back to local mode, which means continual broadcast >>>> IPIs or TLBIEs are needed for TLB flushing. This patch prevents that >>>> situation too. >>>> >>>> Signed-off-by: Nicholas Piggin <npig...@gmail.com> >>> >>> Thanks for your patch! >>> >>>> --- a/arch/powerpc/platforms/powermac/smp.c >>>> +++ b/arch/powerpc/platforms/powermac/smp.c >>>> @@ -911,6 +911,8 @@ static int smp_core99_cpu_disable(void) >>>> >>>> mpic_cpu_set_priority(0xf); >>>> >>>> + cleanup_cpu_mmu_context(); >>>> + >>> >>> I guess this change broke pmac32_defconfig+SMP in v5.10-rc7? >>> >>> arch/powerpc/platforms/powermac/smp.c: error: implicit >>> declaration of function 'cleanup_cpu_mmu_context' >>> [-Werror=implicit-function-declaration]: => 914:2 >>> >>> http://kisskb.ellerman.id.au/kisskb/buildresult/14423174/ >> >> Hey, yeah it does thanks for catching it. This patch fixes it for me >> >> --- >> From a9b5ec92ffac975e81c6d7db6ff2b1486b2723f7 Mon Sep 17 00:00:00 2001 >> From: Nicholas Piggin <npig...@gmail.com> >> Date: Mon, 14 Dec 2020 13:52:39 +1000 >> Subject: [PATCH] powerpc/32s: Fix cleanup_cpu_mmu_context() compile bug >> >> 32s has no tlbiel_all() defined, so just disable the cleanup with a >> comment. > > Or what about just:
That works, I kind of wanted it in there explicit that we don't clean up on 32s. I don't mind if you prefer this though. Thanks, Nick > > diff --git a/arch/powerpc/include/asm/book3s/32/mmu-hash.h > b/arch/powerpc/include/asm/book3s/32/mmu-hash.h > index 331187661236..685c589e723f 100644 > --- a/arch/powerpc/include/asm/book3s/32/mmu-hash.h > +++ b/arch/powerpc/include/asm/book3s/32/mmu-hash.h > @@ -94,6 +94,7 @@ typedef struct { > } mm_context_t; > > void update_bats(void); > +static inline void cleanup_cpu_mmu_context(void) { }; > > /* patch sites */ > extern s32 patch__hash_page_A0, patch__hash_page_A1, patch__hash_page_A2; > > > cheers > >