Re: [PATCH v15 01/13] x86/sev: Carve out and export SNP guest messaging init routines

[Nikunj A. Dadhania]

On 12/3/2024 7:49 PM, Borislav Petkov wrote:
> On Tue, Dec 03, 2024 at 02:30:33PM +0530, Nikunj A Dadhania wrote:
>> @@ -458,6 +456,20 @@ void set_pte_enc_mask(pte_t *kpte, unsigned long pfn, pgprot_t new_prot);
>>  void snp_kexec_finish(void);
>>  void snp_kexec_begin(void);
>>  
>> +static inline bool snp_is_vmpck_empty(struct snp_msg_desc *mdesc)
>> +{
>> +	static const char zero_key[VMPCK_KEY_LEN] = {0};
>> +
>> +	if (mdesc->vmpck)
>> +		return !memcmp(mdesc->vmpck, zero_key, VMPCK_KEY_LEN);
>> +
>> +	return true;
>> +}
> 
> This function looks silly in a header with that array allocation.
> 
> I think you should simply do:
> 
> 	if (memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN))

Just a minor nit, it will need a negation:

 	if (!memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN))
 
> at the call sites and not have this helper at all.
> 
> But please do verify whether what I'm saying actually makes sense and if it
> does, this can be a cleanup pre-patch.

Yes, it makes sense. I have verified the code and below is the cleanup pre-patch.