[PATCH] RISC-V: Avoid coupling the T-Head CMOs and Zicbom

[Palmer Dabbelt]

On Thu, 15 Sep 2022 14:15:13 PDT (-0700), heiko at sntech.de wrote:
> Am Donnerstag, 15. September 2022, 19:09:00 CEST schrieb Palmer Dabbelt:
>> We could make the T-Head CMOs depend on a new-enough assembler to have
>> Zicbom, but it's not strictly necessary because the T-Head CMOs
>> circumvent the assembler.
>>
>> Fixes: 8f7e001e0325 ("RISC-V: Clean up the Zicbom block size probing")
>> Cc: stable at vger.kernel.org
>> Reported-by: kernel test robot <lkp at intel.com>
>> Reported-by: Conor Dooley <conor.dooley at microchip.com>
>> Signed-off-by: Palmer Dabbelt <palmer at rivosinc.com>
>
> Reviewed-by: Heiko Stuebner <heiko at sntech.de>

Thanks, this is on fixes (a little late this week due to the 
conferences, but I'm still hoping for rc6).

>
>> ---
>>  arch/riscv/include/asm/cacheflush.h | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/riscv/include/asm/cacheflush.h b/arch/riscv/include/asm/cacheflush.h
>> index a89c005b4bbf..273ece6b622f 100644
>> --- a/arch/riscv/include/asm/cacheflush.h
>> +++ b/arch/riscv/include/asm/cacheflush.h
>> @@ -42,8 +42,12 @@ void flush_icache_mm(struct mm_struct *mm, bool local);
>>
>>  #endif /* CONFIG_SMP */
>>
>> -#ifdef CONFIG_RISCV_ISA_ZICBOM
>> +/*
>> + * The T-Head CMO errata internally probe the CBOM block size, but otherwise
>> + * don't depend on Zicbom.
>> + */
>>  extern unsigned int riscv_cbom_block_size;
>> +#ifdef CONFIG_RISCV_ISA_ZICBOM
>>  void riscv_init_cbom_blocksize(void);
>>  #else
>>  static inline void riscv_init_cbom_blocksize(void) { }
>>