Introduce two kinds of events for each vcpu,
VCPU_EVENT_IOREQ: for vcpu waiting for IO request completion
VCPU_EVENT_VIRTUAL_INTERRUPT: for vcpu waiting for virtual interrupts events
vcpu can wait for such events, and resume to run when the
event get signalled.
This patch also change IO request waiting/notifying to this way.
Tracked-On: #4329
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
e3c303363b