Guest OS (e.g. Linux) may rely on a gap in E820 map in the 32-bit memory
space to determine the MMIO space for its PCI devices. Leave this gap
when building E820 map to keep the guest's PCI subsystem working.
After commit 7752d5cfe3d11ca0bb9c673ec38bd78ba6578f8e, Linux kernel no
longer requires the MMCONFIG region to be reserved in the E820 map.
Nonetheless, keep it in the reserved region to be on the safe side.
Tracked-On: #2843
Signed-off-by: Peter Fang <peter.fang@intel.com>
Acked-by: Yin Fengwei <fengwei.yin@intel.com>
20164799cb