Re: [RFC] hypercall-vsock: add a new vsock transport

[Stefano Garzarella]

On Wed, Nov 10, 2021 at 07:12:36AM +0000, Wang, Wei W wrote:
> Hi,
>
> We plan to add a new vsock transport based on hypercall (e.g. vmcall on Intel CPUs).
> It transports AF_VSOCK packets between the guest and host, which is similar to
> virtio-vsock, vmci-vsock and hyperv-vsock.
>
> Compared to the above listed vsock transports which are designed for high performance,
> the main advantages of hypercall-vsock are:
>
> 1)       It is VMM agnostic. For example, one guest working on hypercall-vsock can run on
>
> either KVM, Hyperv, or VMware.
>
> 2)       It is simpler. It doesn't rely on any complex bus enumeration
>
> (e.g. virtio-pci based vsock device may need the whole implementation of PCI).
>
> An example usage is the communication between MigTD and host (Page 8 at
> https://static.sched.com/hosted_files/kvmforum2021/ef/TDX%20Live%20Migration_Wei%20Wang.pdf).
> MigTD communicates to host to assist the migration of the target (user) 
> TD.
> MigTD is part of the TCB, so its implementation is expected to be as simple as possible
> (e.g. bare mental implementation without OS, no PCI driver support).

Adding Andra and Sergio, because IIRC Firecracker and libkrun emulates 
virtio-vsock with virtio-mmio so the implementation should be simple and 
also not directly tied to a specific VMM.

Maybe this fit for your use case too, in this way we don't have to 
maintain another driver.

Thanks,
Stefano