vfio/common: Separate vfio-pci ranges

vfio/common: Separate vfio-pci ranges

QEMU computes the DMA logging ranges for two predefined ranges: 32-bit
and 64-bit. In the OVMF case, when the dynamic MMIO window is enabled,
QEMU includes in the 64-bit range the RAM regions at the lower part
and vfio-pci device RAM regions which are at the top of the address
space. This range contains a large gap and the size can be bigger than
the dirty tracking HW limits of some devices (MLX5 has a 2^42 limit).

To avoid such large ranges, introduce a new PCI range covering the
vfio-pci device RAM regions, this only if the addresses are above 4GB
to avoid breaking potential SeaBIOS guests.

[ clg: - wrote commit log
       - fixed overlapping 32-bit and PCI ranges when using SeaBIOS ]

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Fixes: 5255bbf4ec16 ("vfio/common: Add device dirty page tracking start/stop")
Signed-off-by: Cédric Le Goater <clg@redhat.com>