This is the native ivshmem-server implementation catering to the GCE CVD vSoC project.
We are breaking from the general philosophy of ivshmem-server inter-vm communication.
There is no concept of inter-vm communication. The server itself is meant to run on the L1 Guest (or L0 even). We will call this domain as ‘host-side’. The following functions are envisoned:
Create the shared-memory window, listen for VM connection (and subsequent disconnection). Note that the server can only accomodate one VM connection at a time. This may need to be enforced as there may be mulitple VMs (but each of them need a dedicated shared_memory and VM <--> server UNIX Domain sockets).
Parse a JSON file describing memory layout and other information. Use this information to initialize the shared memory.
Create two UNIX Domain sockets. One to communicate with QEMU and the other to communicate with host clients.
For QEMU, speak the ivshmem protocol, i.e. pass a vmid, pass the shm fd to the qemu VM along with event fds. One for host to guest signalling and the other for guest to host signalling. Please see: QEMU_SRC/docs/specs/ivshmem-spec.txt. The only twist is that the server pretends to be another peer VM to comply to the ivshmem protocol.
For the client, speak the ad-hoc client protocol:
ivshmem_client <--> ivshmem_server handshake.
Client -> ‘GET PROTOCOL_VER’ Server -> ‘PROTOCOL_VER 0’ Client -> INFORM REGION_NAME_LEN: 0x0000000a Client -> GET REGION: HW_COMPOSER Server -> 0xffffffff(If region name not found) Server -> 0xAABBC000 (region start offset) Server -> 0xAABBC0000 (region end offset) Server -> Server -> Server ->
This also launches QEMU with the appropriate parameters
Building: From this directory issue the following in the command line bazel build src:ivserver
Running: Once the binary is built using bazel. Just run it from this directory as the default options expect the JSON files under conf directory. e.g. ./bazel-bin/src/ivserver
If you encounter either
Please run the following commands and retry launching. rm /dev/shm/ivshmem rm /tmp/ivsh*
TODO: