Re: [PATCH v2 1/2] xen/domain: Annotate struct domain as page aligned

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.03.2025 22:29, Andrew Cooper wrote:
> On 05/03/2025 9:23 am, Jan Beulich wrote:
>> On 04.03.2025 00:29, Andrew Cooper wrote:
>>> --- a/xen/include/xen/sched.h
>>> +++ b/xen/include/xen/sched.h
>>> @@ -645,7 +645,7 @@ struct domain
>>>      unsigned int num_llc_colors;
>>>      const unsigned int *llc_colors;
>>>  #endif
>>> -};
>>> +} __aligned(PAGE_SIZE);
>>>  
>>>  static inline struct page_list_head *page_to_list(
>>>      struct domain *d, const struct page_info *pg)
>> I understand struct domain is where you need the annotation right away, but 
>> is
>> there a reason not to do the same for struct vcpu right away?
> 
> struct vcpu is more complicated.  It's multi-page on ARM, and I have a
> strong suspicion that alignment is going to have to change away from
> PAGE_SIZE for architectures wanting to use larger page sizes.
> 
> e.g. with 64k pagetables, I expect these will still want 4k alignment,
> and therefore they'll all want changing. i.e. I'm probably creating less
> work for someone in the future by not annotating struct vcpu. ~Andrew

Wouldn't the same hold for struct domain?

Jan