Re: [PATCH v4 6/6] xen: retrieve reserved pages on populate_physmap

[Jan Beulich <jbeulich@suse.com>]

On 10.05.2022 04:27, Penny Zheng wrote:
> @@ -2769,12 +2769,43 @@ int __init acquire_domstatic_pages(struct domain *d, mfn_t smfn,
>  
>      return 0;
>  }
> +
> +/*
> + * Acquire a page from reserved page list(resv_page_list), when populating
> + * memory for static domain on runtime.
> + */
> +mfn_t acquire_reserved_page(struct domain *d, unsigned int memflags)
> +{
> +    struct page_info *page;
> +    mfn_t smfn;
> +
> +    /* Acquire a page from reserved page list(resv_page_list). */
> +    page = page_list_remove_head(&d->resv_page_list);
> +    if ( unlikely(!page) )
> +        return INVALID_MFN;
> +
> +    smfn = page_to_mfn(page);
> +
> +    if ( acquire_domstatic_pages(d, smfn, 1, memflags) )
> +    {
> +        page_list_add_tail(page, &d->resv_page_list);
> +        return INVALID_MFN;
> +    }
> +
> +    return smfn;
> +}
>  #else
>  void free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
>                            bool need_scrub)
>  {
>      ASSERT_UNREACHABLE();
>  }
> +
> +mfn_t acquire_reserved_page(struct domain *d, unsigned int memflags)
> +{
> +    ASSERT_UNREACHABLE();
> +    return INVALID_MFN;
> +}
>  #endif

Much like for the other stub function added in the earlier patch: If
is_domain_using_staticmem() was compile time constant "false" when
!CONFIG_STATIC_MEM, there would be no need for this one since the
compiler would DCE the only call site.