Excerpts from Christophe Leroy's message of December 20, 2020 9:43 pm:
>
>
> Le 20/12/2020 à 00:48, Nicholas Piggin a écrit :
>> This allows some nest MMU features to be compiled away if coprocessor
>> support is not selected.
>>
>> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
>> ---
>> arch/powerpc/Kconfig | 1 +
>> arch/powerpc/include/asm/book3s/64/mmu.h | 2 ++
>> arch/powerpc/include/asm/book3s/64/tlbflush.h | 2 ++
>> arch/powerpc/include/asm/mmu_context.h | 5 +++--
>> arch/powerpc/platforms/Kconfig | 3 +++
>> arch/powerpc/platforms/powernv/Kconfig | 1 +
>> 6 files changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index ae7391627054..4376bf4c53b4 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -888,6 +888,7 @@ config PPC_PROT_SAO_LPAR
>>
>> config PPC_COPRO_BASE
>> bool
>> + select PPC_NMMU if PPC_BOOK3S_64
>>
>> config SCHED_SMT
>> bool "SMT (Hyperthreading) scheduler support"
>> diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h
>> b/arch/powerpc/include/asm/book3s/64/mmu.h
>> index 995bbcdd0ef8..07850d68a624 100644
>> --- a/arch/powerpc/include/asm/book3s/64/mmu.h
>> +++ b/arch/powerpc/include/asm/book3s/64/mmu.h
>> @@ -103,8 +103,10 @@ typedef struct {
>> /* Number of bits in the mm_cpumask */
>> atomic_t active_cpus;
>>
>> +#ifdef CONFIG_PPC_NMMU
>> /* Number of users of the external (Nest) MMU */
>> atomic_t copros;
>> +#endif
>>
>> /* Number of user space windows opened in process mm_context */
>> atomic_t vas_windows;
>> diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush.h
>> b/arch/powerpc/include/asm/book3s/64/tlbflush.h
>> index 0a7431e954c6..c70a82851f78 100644
>> --- a/arch/powerpc/include/asm/book3s/64/tlbflush.h
>> +++ b/arch/powerpc/include/asm/book3s/64/tlbflush.h
>> @@ -16,8 +16,10 @@ enum {
>>
>> static inline bool mm_has_nmmu(struct mm_struct *mm)
>> {
>> +#ifdef CONFIG_PPC_NMMU
>> if (unlikely(atomic_read(&mm->context.copros) > 0))
>> return true;
>> +#endif
>> return false;
>> }
>>
>> diff --git a/arch/powerpc/include/asm/mmu_context.h
>> b/arch/powerpc/include/asm/mmu_context.h
>> index d5821834dba9..53eac0cc4929 100644
>> --- a/arch/powerpc/include/asm/mmu_context.h
>> +++ b/arch/powerpc/include/asm/mmu_context.h
>> @@ -143,6 +143,7 @@ static inline void dec_mm_active_cpus(struct mm_struct
>> *mm)
>> atomic_dec(&mm->context.active_cpus);
>> }
>>
>> +#ifdef CONFIG_PPC_NMMU
>> static inline void mm_context_add_copro(struct mm_struct *mm)
>> {
>> /*
>> @@ -187,6 +188,7 @@ static inline void mm_context_remove_copro(struct
>> mm_struct *mm)
>> dec_mm_active_cpus(mm);
>> }
>> }
>> +#endif
>>
>> /*
>> * vas_windows counter shows number of open windows in the mm
>> @@ -218,8 +220,7 @@ static inline void mm_context_remove_vas_window(struct
>> mm_struct *mm)
>> #else
>> static inline void inc_mm_active_cpus(struct mm_struct *mm) { }
>> static inline void dec_mm_active_cpus(struct mm_struct *mm) { }
>> -static inline void mm_context_add_copro(struct mm_struct *mm) { }
>> -static inline void mm_context_remove_copro(struct mm_struct *mm) { }
>
> Are you sure you can remove those ?
> If so, I think it belongs to another patch, I can't see how the new PPC_NMMU
> would allow that by itself.
Yeah possibly a separate patch. Nothing except 64s should compile such
code though, I think?
Thanks,
Nick
