Re: xenheap pages mapped by dom0

[George Dunlap <george.dunlap@eu.citrix.com>]

Keir Fraser wrote:
> I think the right thing to do would be very roughly:
> On allocation:
>  page = alloc_xenheap_page();
>  share_xen_page_with_guest(page);
> On deallocation:
>  if (test_and_clear(PGC_allocated)) put_page();
>  if (page->count_info & PGC_count_mask) return -EBUSY;
>  free_xenheap_page(page);
>   
Hmm, the first two should probably happen in the opposite order, no?  
I.e., we should check to see that for each page we want to deallocate, 
page->count_info & PGC_count_mask == 0, returning -EBUSY if that fails; 
then unmark allocate and call free xenheap page?

 -George