device assignment: Add PCI option ROM support
The PCI code already knows about option ROMs, so we just need to
mmap some space for it, load it with a copy of the contents, and
complete the plubming to the generic code.
With this a Linux guest can get access to the ROM contents via
/sys/bus/pci/devices/<dev>/rom. This might also enable the BIOS
to execute ROMs by loading them dynamically from the device
rather than hoping they all fit into RAM.
Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Avi Kivity <avi@redhat.com>