Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Thu, 10 Dec 2020 10:06:50 +0100 | Subject | Re: [PATCH 2/2] powerpc/64s: Trim offlined CPUs from mm_cpumasks |
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Hi Nicholas,
On Fri, Nov 20, 2020 at 4:01 AM Nicholas Piggin <npiggin@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 <npiggin@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/
> return 0; > } > > diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c > index 54c4ba45c7ce..cbb67813cd5d 100644 > --- a/arch/powerpc/platforms/powernv/smp.c > +++ b/arch/powerpc/platforms/powernv/smp.c > @@ -143,6 +143,9 @@ static int pnv_smp_cpu_disable(void) > xive_smp_disable_cpu(); > else > xics_migrate_irqs_away(); > + > + cleanup_cpu_mmu_context(); > + > return 0; > } > > diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c > index f2837e33bf5d..a02012f1b04a 100644 > --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c > +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c > @@ -90,6 +90,9 @@ static int pseries_cpu_disable(void) > xive_smp_disable_cpu(); > else > xics_migrate_irqs_away(); > + > + cleanup_cpu_mmu_context(); > + > return 0; > } > > -- > 2.23.0 >
-- Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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