Re: [PATCH v3 5/8] xen/arm: Add additional reference to owner domain when the owner is allocated

[Julien Grall <julien@xxxxxxx>]

On 12/05/2022 10:11, Penny Zheng wrote:
> @@ -827,6 +858,37 @@ static int __init allocate_shared_memory(struct domain *d,
>           }
>       }
>   
> +    /*
> +     * Get the right amount of references per page, which is the number of
> +     * borrow domains.
> +     */
> +    ret = acquire_nr_borrower_domain(d, pbase, psize, &nr_borrowers);
> +    if ( ret )
> +        return ret;
> +
> +    /*
> +     * Instead of let borrower domain get a page ref, we add as many
> +     * additional reference as the number of borrowers when the owner
> +     * is allocated, since there is a chance that owner is created
> +     * after borrower.
> +     */
> +    page = mfn_to_page(smfn);
Where do you check that the range [smfn, smfn + nr_pages] is actual RAM? 
If there are none, then you should use mfn_valid() for each mfn to 
ensure there will be a struct page for it.
Cheers,

--
Julien Grall