[PATCH v5 18/26] powerpc/book3s64/keys/kuap: Reset AMR/IAMR values on kexec

[Aneesh Kumar K.V]

On 7/6/20 5:59 PM, Michael Ellerman wrote:
> "Aneesh Kumar K.V" <aneesh.kumar at linux.ibm.com> writes:
>> As we kexec across kernels that use AMR/IAMR for different purposes
>> we need to ensure that new kernels get kexec'd with a reset value
>> of AMR/IAMR. For ex: the new kernel can use key 0 for kernel mapping and the old
>> AMR value prevents access to key 0.
>>
>> This patch also removes reset if IAMR and AMOR in kexec_sequence. Reset of AMOR
>> is not needed and the IAMR reset is partial (it doesn't do the reset
>> on secondary cpus) and is redundant with this patch.
> 
> I like the idea of cleaning this stuff up.
> 
> But I think tying it into kup/kuep/kuap and the MMU features and ifdefs
> and so on is overly complicated.
> 
> We should just have eg:
> 
> void reset_sprs(void)
> {
> 	if (early_cpu_has_feature(CPU_FTR_ARCH_206)) {
>          	mtspr(SPRN_AMR, 0);
>          	mtspr(SPRN_UAMOR, 0);
>          }
> 
> 	if (early_cpu_has_feature(CPU_FTR_ARCH_207S)) {
>          	mtspr(SPRN_IAMR, 0);
>          }
> }
> 
> And call that from the kexec paths.
>

Will fix. Should that be early_cpu_has_feature()? cpu_has_feature() 
should work there right?

-aneesh