On 3/9/21 7:35 PM, Will Deacon wrote:
> On Mon, Mar 08, 2021 at 02:42:00PM +0000, Marc Zyngier wrote:
>> On Fri, 05 Mar 2021 14:36:09 +0000,
>> Anshuman Khandual <anshuman.khand...@arm.com> wrote:
>>> -   switch (cpuid_feature_extract_unsigned_field(mmfr0, tgran_2)) {
>>> -   default:
>>> -   case 1:
>>> +   tgran_2 = cpuid_feature_extract_unsigned_field(mmfr0, tgran_2_shift);
>>> +   if (tgran_2 == ID_AA64MMFR0_TGRAN_2_SUPPORTED_NONE) {
>>>             kvm_err("PAGE_SIZE not supported at Stage-2, giving up\n");
>>>             return -EINVAL;
>>> -   case 0:
>>> +   } else if (tgran_2 == ID_AA64MMFR0_TGRAN_2_SUPPORTED_DEFAULT) {
>>>             kvm_debug("PAGE_SIZE supported at Stage-2 (default)\n");
>>> -           break;
>>> -   case 2:
>>> +   } else if (tgran_2 >= ID_AA64MMFR0_TGRAN_2_SUPPORTED_MIN &&
>>> +              tgran_2 <= ID_AA64MMFR0_TGRAN_2_SUPPORTED_MAX) {
>>>             kvm_debug("PAGE_SIZE supported at Stage-2 (advertised)\n");
>>> -           break;
>>> +   } else {
>>> +           kvm_err("Unsupported value, giving up\n");
>>> +           return -EINVAL;
>>
>> nit: this doesn't say *what* value is unsupported, and I really
>> preferred the switch-case version, such as this:
>>
>> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
>> index 1f22b36a0eff..d267e4b1aec6 100644
>> --- a/arch/arm64/kvm/reset.c
>> +++ b/arch/arm64/kvm/reset.c
>> @@ -312,15 +312,18 @@ int kvm_set_ipa_limit(void)
>>  
>>      switch (cpuid_feature_extract_unsigned_field(mmfr0, tgran_2)) {
>>      default:
>> -    case 1:
>> +    case ID_AA64MMFR0_TGRAN_2_SUPPORTED_NONE:
>>              kvm_err("PAGE_SIZE not supported at Stage-2, giving up\n");
>>              return -EINVAL;
>> -    case 0:
>> +    case ID_AA64MMFR0_TGRAN_2_SUPPORTED_DEFAULT:
>>              kvm_debug("PAGE_SIZE supported at Stage-2 (default)\n");
>>              break;
>> -    case 2:
>> +    case ID_AA64MMFR0_TGRAN_2_SUPPORTED_MIN ... 
>> ID_AA64MMFR0_TGRAN_2_SUPPORTED_MAX:
>>              kvm_debug("PAGE_SIZE supported at Stage-2 (advertised)\n");
>>              break;
>> +    default:
>> +            kvm_err("Unsupported value for TGRAN_2, giving up\n");
>> +            return -EINVAL;
>>      }
>>  
>>      kvm_ipa_limit = id_aa64mmfr0_parange_to_phys_shift(parange);
>>
>>
>> Otherwise:
>>
>> Acked-by: Marc Zyngier <m...@kernel.org>
> 
> Anshuman -- please can you spin a v2 with the switch syntax as suggested
> above by Marc?

Sure, will do.

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