On Wed 19-07-17 20:01:18, Wei Wang wrote:
On 07/19/2017 04:13 PM, Michal Hocko wrote:
[...
All you should need is the check for the page reference count, no? I
assume you do some sort of pfn walk and so you should be able to get an
access to the struct page.
Not necessarily - the guest struct page is not seen by the hypervisor. The
hypervisor only gets those guest pfns which are hinted as unused. From the
hypervisor (host) point of view, a guest physical address corresponds to a
virtual address of a host process. So, once the hypervisor knows a guest
physical page is unsued, it knows that the corresponding virtual memory of
the process doesn't need to be transferred in the 1st round.
I am sorry, but I do not understand. Why cannot _guest_ simply check the
struct page ref count and send them to the hypervisor?