> From: Zhu, Lingshan <lingshan....@intel.com> > Sent: Wednesday, September 20, 2023 12:37 PM
> > The problem to overcome in [1] is, resume operation needs to be synchronous > as it involves large part of context to resume back, and hence just > asynchronously setting DRIVER_OK is not enough. > > The sw must verify back that device has resumed the operation and ready to > answer requests. > this is not live migration, all device status and other information still > stay in the > device, no need to "resume" context, just resume running. > I am aware that it is not live migration. :) "Just resuming" involves lot of device setup task. The device implementation does not know for how long a device is suspended. So for example, a VM is suspended for 6 hours, hence the device context could be saved in a slow disk. Hence, when the resume is done, it needs to setup things again and driver got to verify before accessing more from the device. > Like resume from a failed LM. > > > > This is slightly different flow than setting the DRIVER_OK for the first > > time > device initialization sequence as it does not involve large restoration. > > > > So, to merge two ideas, instead of doing DRIVER_OK to resume, the driver > should clear the SUSPEND bit and verify that it is out of SUSPEND. > > > > Because driver is still in _OK_ driving the device flipping the SUSPEND bit. > Please read the spec, it says: > The driver MUST NOT clear a device status bit > Yes, this is why either DRIER_OK validation by the driver is needed or Jiqian's synchronous new register..
