Re: [PATCH v12 6/6] xen: retrieve reserved pages on populate_physmap

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.09.2022 09:39, Penny Zheng wrote:
> When a static domain populates memory through populate_physmap at runtime,
> it shall retrieve reserved pages from resv_page_list to make sure that
> guest RAM is still restricted in statically configured memory regions.
> This commit also introduces a new helper acquire_reserved_page to make it 
> work.
> 
> Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>

Just FTR: I have no further comments here, but I'm also not going to ack
this change with ...

> --- a/xen/common/memory.c
> +++ b/xen/common/memory.c
> @@ -245,6 +245,29 @@ static void populate_physmap(struct memop_args *a)
>  
>                  mfn = _mfn(gpfn);
>              }
> +            else if ( is_domain_using_staticmem(d) )
> +            {
> +                /*
> +                 * No easy way to guarantee the retrieved pages are 
> contiguous,
> +                 * so forbid non-zero-order requests here.
> +                 */
> +                if ( a->extent_order != 0 )
> +                {
> +                    gdprintk(XENLOG_WARNING,
> +                             "Cannot allocate static order-%u pages for 
> %pd\n",
> +                             a->extent_order, d);
> +                    goto out;
> +                }
> +
> +                mfn = acquire_reserved_page(d, a->memflags);
> +                if ( mfn_eq(mfn, INVALID_MFN) )
> +                {
> +                    gdprintk(XENLOG_WARNING,
> +                             "%pd: failed to retrieve a reserved page\n",
> +                             d);
> +                    goto out;
> +                }
> +            }
>              else
>              {
>                  page = alloc_domheap_pages(d, a->extent_order, a->memflags);

... the gdprintk() left in here. I'm sure someone else (Julien?) will provide
the necessary ack.

Jan