p2m/ept: enable PML in p2m-ept for log-dirty

p2m/ept: enable PML in p2m-ept for log-dirty

This patch firstly enables EPT A/D bits if PML is used, as PML depends on EPT
A/D bits to work. A bit is set for all present p2m types in middle and leaf EPT
entries, and D bit is set for all writable types in EPT leaf entry, except for
log-dirty type with PML.

With PML, for 4K pages, instead of setting EPT entry to read-only, we just need
to clear D bit in order to log that GFN. For superpages, we still need to set it
to read-only as we need to split superpage to 4K pages in EPT violation.

Signed-off-by: Kai Huang <kai.huang@linux.intel.com>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Kevin Tian <kevin.tian@intel.com>