Ovmfpkg/VirtioBlkDxe: map virtio-blk request and response buffers
When device is behind the IOMMU, driver is require to pass the device
address of virtio request, response and any memory referenced by those
request/response to the bus master.
The patch uses IOMMU-like member functions from VIRTIO_DEVICE_PROTOCOL to
map request and response buffers system physical address to the device
address.
- If the buffer need to be accessed by both the processor and a bus
master then map with BusMasterCommonBuffer.
- If the buffer need to be accessed for a write operation by a bus master
then map with BusMasterWrite.
- If the buffer need to be accessed for a read operation by a bus master
then map with BusMasterRead.