Xen + xmm-xen fixes to test (suspend/resume fixes, directio loopback devices, sys-usb fails to start, slowness vs bare metal)

I’m experiencing slowness as never before.
When compiling stuff (enough ram all available cpus usable), my mouse stops moving sometimes, like if dom0 (where xorg is) was not having enough priority.

This behavior is new since about a week. Will try to isolate, everything now from stable repo.