Re: [PATCH 05/12] xen: introduce reserve_heap_pages

[Julien Grall <julien@xxxxxxx>]

On 15/04/2020 02:02, Stefano Stabellini wrote:
> Introduce a function named reserve_heap_pages (similar to
> alloc_heap_pages) that allocates a requested memory range. Call
> __alloc_heap_pages for the implementation.
>
> Change __alloc_heap_pages so that the original page doesn't get
> modified, giving back unneeded memory top to bottom rather than bottom
> to top.
>
> Also introduce a function named reserve_domheap_pages, similar to
> alloc_domheap_pages, that checks memflags before calling
> reserve_heap_pages. It also assign_pages to the domain on success.
Xen may have already allocated the part of region for its own purpose or 
for another domain. So this will not work reliably.
We have the same issues with LiveUpdate as memory have to be preserved. 
We need to mark the page reserved before any allocation (including early 
boot allocation) so nobody can use them. See [1].
Cheers,

[1]  Live update: boot memory management, data stream handling, record 
format <a92287c03fed310e08ba40063e370038569b94ac.camel@xxxxxxxxxxxxx>
--
Julien Grall