dom0 pvh: linux: issues without dom0_mem

[Mukesh Rathor <mukesh.rathor@oracle.com>]

Konrad,

Looks like there are bunch of things in the xen_set_identity_and_release
code for pvh. Things crap out for dom0 when dom0_mem is not specified.

For one, the code in  xen_pvh_adjust_stats():

                unsigned long end = min(max_pfn_mapped, end_pfn);

is wrong. The result is a negative number, and causes released to be
set improperly:

[    0.000000] Released 18446744073707253146 pages of unused memory

This then later causes xen_do_chunk to barf:

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at /home/sb/hybrid/linux-v3.12/arch/x86/xen/setup.c:134 xen_do_chunk+0x1a0/0x247()
[    0.000000] Failed to populate pfn 271f85 err=0


Second, I don't remember or understand why we removed the xen_release_chunk
from pvh path, and now just collect the stats. If anything is mapped, it 
would need to be removed. Oh never mind, i remember, because when the iomap
is done by xen, it has already removed those pages. Hmm... so let me
figure how to fix xen_pvh_adjust_stats(). I'll send patch. JFYI you and
others.

thanks
Mukesh