Example patch to send SGIs with a hypercall

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Hi all,

Next week I'll be giving a talk about VM-to-VM communication mechanisms
at Embedded Linux Conf in Seattle.

One of the techniques I'll discuss, also the simplest, is shared memory
and interrupts. Although there is no binding to share memory between
dom0less VMs yet, it is already possible to do that with a workaround.
But it is not possible to send interrupts between dom0less VMs yet.

The attached patch introduces a trivial hypercall to inject SGI
interrupts into other Dom0less VMs. It is easy to use for baremetal
guests and other kernels without Xen support (no Xen drivers needed).
I'd like to share the patch publicly in advance of the talk, so that I
can reference it during the presentation. The patch is not meant for
upstreaming at this point.

Beware that it comes with no usage restrictions (no rate limiting
and/or no target limits).

Cheers,

Stefano

Attachment: xen-sgi.patch
Description: Text Data