Re: [PATCH v2 07/11] xen: move domain_use_host_layout() to common code

[Oleksii Kurochko <oleksii.kurochko@gmail.com>]

On 4/1/26 7:59 AM, Jan Beulich wrote:
> On 31.03.2026 21:49, Oleksii Kurochko wrote:
>> On 3/31/26 6:32 PM, Oleksii Kurochko wrote:
>>>>>>> @@ -2544,6 +2544,12 @@ void thaw_domains(void)
>>>>>>>     #endif /* CONFIG_SYSTEM_SUSPEND */
>>>>>>> +bool domain_use_host_layout(struct domain *d)
>>>>>>> +{
>>>>>>> +    return is_domain_direct_mapped(d) ||
>>>>>>> +           (paging_mode_translate(d) && is_hardware_domain(d));
>>>>>>> +}
>>>>>>
>>>>>> The placement of paging_mode_translate() doesn't match ...
>>>>>>
>>>>>>> --- a/xen/include/xen/domain.h
>>>>>>> +++ b/xen/include/xen/domain.h
>>>>>>> @@ -62,6 +62,22 @@ void domid_free(domid_t domid);
>>>>>>>     #define is_domain_direct_mapped(d) ((d)->cdf & CDF_directmap)
>>>>>>>     #define is_domain_using_staticmem(d) ((d)->cdf & CDF_staticmem)
>>>>>>> +/*
>>>>>>> + * Is the auto-translated domain using the host memory layout?
>>>>>>> + *
>>>>>>> + * domain_use_host_layout() is always False for PV guests.
>>>>>>
>>>>>> ... the description of the function.
>>>>>
>>>>> But why the placement should be different?
>>>>
>>>> If you focus on auto-translated, then imo paging_mode_translate()
>>>> better would guard everything.
>>>
>>> Then it make sense to do in the following way:
>>>    bool domain_use_host_layout(struct domain *d)
>>>    {
>>> -    return is_domain_direct_mapped(d) ||
>>> -           (paging_mode_translate(d) && is_hardware_domain(d));
>>> +    return paging_mode_translate(d) &&
>>> +           (is_domain_direct_mapped(d) || is_hardware_domain(d));
>>>    }
>>
>> This is not really correct.
> 
> ... because of ... ? (After all, then the comment isn't correct either.)

I thought it could break what Arm had before when 
paging_mode_translate() is false, but it is always true for Arm, so with 
paging_mode_translate() being true, the new definition is equivalent to 
what it had before. So looks goods.

~ Oleksii


> 
> Jan