The implementation of the virtio-balloon was slightly wrong as it was
generating the GPA (Guest Physical Address) from the PFN (Page Frame
Number) which was a u32. That means the GPA was created as a u32, and
later a cast was done to extend it to a u64 type. Unfortunately, by
doing so, the GPA was wrong if the value was supposedly more than 32
bits.
That's why the PFN is casted into a u64 before the GPA is generated,
which creates the GPA on 64 bits directly.
Additionally, this patch simplifies the process_queue() function,
relying on multiple vm-memory helpers.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
