On Sun, Nov 09, 2025 at 09:13:13PM +0800, Robert Hoo wrote: > On 11/6/2025 10:32 PM, Stefano Garzarella wrote: > > On Fri, Oct 10, 2025 at 09:00:21PM +0800, Robert Hoo wrote: > > > Hi, > > > > > > Does vsock support communication between guests? > > > From man page, and my experiment, seems it doesn't. > > > But why not? > > > > > > > It depends, vhost-user vsock device, supports it. > > See > > https://github.com/rust-vmm/vhost-device/tree/main/vhost-device-vsock#sibling-vm-communication > > > > The vhost-vsock in-kernel device doesn't support it. > > > > The main problem is that vsock is designed for host<->guest > > communication, so implementing a guest<->guest communication is > > possible, but requires more configuration (e.g. some kind of firewall, > > etc.) and also an extension to the address (see the required > > `.svm_flags = VMADDR_FLAG_TO_HOST` in the link). > > > > The easy way to do that with vhost-vsock, is to use socat in the host to > > concatenate 2 VMs (some examples here: > > https://stefano-garzarella.github.io/posts/2021-01-22-socat-vsock/) > > > > Cheers, > > Stefano > > > Nice, thanks Stefano. It sounds ideal for my VM <--> VM communication > requirement. I'll read the doc carefully later. >
Though not as convenient as socat, VSOCK also supports sockmap which can do this in-kernel (bpf), there are a few test cases for this in selftests/bpf. Best, Bobby
