Hostbridge Emulation

Overview

Hostbridge emulation is based on PCI emulation; however, the hostbridge emulation only sets the PCI configuration space. The Device Model (DM) sets the PCI configuration space for hostbridge in the Service VM and then exposes it to the User VM to detect the PCI hostbridge.

PCI Host Bridge and Hierarchy

There is PCI host bridge emulation in DM. The bus hierarchy is determined by acrn-dm command line input. Using this command line, as an example:

acrn-dm -A -m $mem_size -s 0:0,hostbridge \
-s 2,pci-gvt -G "$2" \
-s 5,virtio-console,@stdio:stdio_port \
-s 6,virtio-hyper_dmabuf \
-s 3,virtio-blk,/home/acrn/UserVM.img \
-s 4,virtio-net,tap0 \
-s 7,virtio-rnd \
--ovmf /usr/share/acrn/bios/OVMF.fd \
$pm_channel $pm_by_vuart $pm_vuart_node \
$logger_setting \
--mac_seed $mac_seed \
$vm_name

the bus hierarchy would be:

# lspci
00:00.0 Host bridge: Network Appliance Corporation Device 1275
00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
00:03.0 SCSI storage controller: Red Hat, Inc. Virtio block device
00:05.0 Serial controller: Red Hat, Inc. Virtio console
00:06.0 RAM memory: Intel Corporation Device 8606
00:08.0 Network and computing encryption device: Red Hat, Inc. Virtio RNG
00:09.0 Ethernet controller: Red Hat, Inc. Virtio network device