On Fri, Oct 14, 2016 at 03:43:19PM -0400, Boris Ostrovsky wrote: > On 10/14/2016 03:19 PM, Konrad Rzeszutek Wilk wrote: > > On Fri, Oct 14, 2016 at 02:05:16PM -0400, Boris Ostrovsky wrote: > > > > Perhaps add in here: > > > > PVH is like PV in that there are no PCI devices - which HVM > > code would piggyback on to find the Xen PCI platform device and > > use its MMIO space to stash the grants in. > > > > For PVH we balloon out memory and stash the grants in there. > > > > (Which begs the next question - where and when do we balloon out the > > normal memory back in?) > > Are you saying that we should get back memory that we gave to grant tables?
Yes. In pure HVM that area is MMIO - which hvmloader has balloonned out. The hvmloader then balloons that number of pages back at the end of guest memory (after 4GB).