[PATCH v4 3/5] arm64: Add support for FEAT_HAFT

[Yicong Yang]

On 2024/11/5 1:28, Catalin Marinas wrote:
> On Sat, Nov 02, 2024 at 06:42:33PM +0800, Yicong Yang wrote:
>> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
>> index 3d261cc123c1..ed8c784ca082 100644
>> --- a/arch/arm64/include/asm/cpufeature.h
>> +++ b/arch/arm64/include/asm/cpufeature.h
>> @@ -838,6 +838,12 @@ static inline bool system_supports_poe(void)
>>  		alternative_has_cap_unlikely(ARM64_HAS_S1POE);
>>  }
>>  
>> +static inline bool system_supports_haft(void)
>> +{
>> +	return IS_ENABLED(CONFIG_ARM64_HAFT) &&
>> +		cpus_have_final_cap(ARM64_HAFT);
>> +}
> 
> I'm fine with this approach. If we ever get hardware with mismatched
> FEAT_HAFT and some secondary CPUs don't come up, we can revisit.
> 
>> diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
>> index ccbae4525891..0bc88df7cb35 100644
>> --- a/arch/arm64/mm/proc.S
>> +++ b/arch/arm64/mm/proc.S
>> @@ -498,6 +498,10 @@ alternative_else_nop_endif
>>  	and	x9, x9, ID_AA64MMFR1_EL1_HAFDBS_MASK
>>  	cbz	x9, 1f
>>  	orr	tcr, tcr, #TCR_HA		// hardware Access flag update
>> +
>> +#ifdef CONFIG_ARM64_HAFT
>> +	orr	tcr2, tcr2, TCR2_EL1x_HAFT
>> +#endif /* CONFIG_ARM64_HAFT */
>>  1:
>>  #endif	/* CONFIG_ARM64_HW_AFDBM */
>>  	msr	mair_el1, mair
> 
> If you still want #ifdefs, I'd have left it outside the HW_AFDBM. We
> already have a dependency in the Kconfig. Anyway, I can fix this up.

yes it has already depend on the HW_AFDBM. And one asm won't cause much to the
Image size if user want CONFIG_ARM64_HAFT=n. I'll drop the #ifdef here.

> I think as an additional patch we can also remove the ID checks for the
> tcr bit in tge HW_AFDBM case. But that's unrelated to this series.

ok. I'll post a separate patch for dropping this.

Thanks.