Re: [XEN PATCH v3 02/16] x86/altp2m: check if altp2m active when giving away p2midx

[Jan Beulich <jbeulich@xxxxxxxx>]

On 07.06.2024 09:25, Jan Beulich wrote:
> On 03.06.2024 13:09, Sergiy Kibrik wrote:
>> @@ -38,9 +34,13 @@ static inline bool altp2m_active(const struct domain *d)
>>  }
>>  
>>  /* Only declaration is needed. DCE will optimise it out when linking. */
>> -uint16_t altp2m_vcpu_idx(const struct vcpu *v);
>>  void altp2m_vcpu_disable_ve(struct vcpu *v);
>>  
>>  #endif
>>  
>> +static inline uint16_t altp2m_vcpu_idx(const struct vcpu *v)
>> +{
>> +    return altp2m_active(v->domain) ? vcpu_altp2m(v).p2midx : 0;
>> +}
> 
> While perhaps okay this way as a first step,

Hmm, or maybe not. 0 is a valid index, and hence could be misleading
at call sites.

Jan

> my general expectation
> would be that with ALTP2M=n there also wouldn't be any p2midx field
> in the respective struct. Which in turn will mean that this code
> would need re-doing again, and perhaps again splitting between an
> inline one and a decl-only one. With that I wonder whether that split
> wouldn't better be retained right away.
> 
> Jan