Re: [Xen-devel] FW: vTPM detaching issue

[Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>]

On 06/29/2016 03:51 AM, Xu, Quan wrote:
> On June 15, 2016 7:49 PM, < wei.liu2@xxxxxxxxxx > wrote:
> > On Tue, Jun 14, 2016 at 12:32:19PM +0200, Andrea Genuise wrote:
> > [...]
> > > libxl: debug: libxl_aoutils.c:88:xswait_timeout_callback: backend
> > > /local/domain/748/backend/vtpm/749/0/state (hoping for state change to
> > 6):
> > > xswait timeout (path=/local/domain/748/backend/vtpm/749/0/state)
> > > libxl: debug: libxl_event.c:677:libxl__ev_xswatch_deregister: watch
> > > w=0x1c4c1f0 wpath=/local/domain/748/backend/vtpm/749/0/state
> > token=3/0:
> > > deregister slotnum=3
> > > libxl: debug: libxl_event.c:867:devstate_callback: backend
> > > /local/domain/748/backend/vtpm/749/0/state wanted state 6  timed out
> > This. The toolstack is waiting for the state to change to 6. But that never
> > happened.
> >
> > > libxl: debug: libxl_event.c:691:libxl__ev_xswatch_deregister: watch
> > > w=0x1c4c1f0: deregister unregistered
> > > libxl: debug: libxl_device.c:937:device_backend_callback: calling
> > > device_backend_cleanup
> > > libxl: debug: libxl_event.c:691:libxl__ev_xswatch_deregister: watch
> > > w=0x1c4c1f0: deregister unregistered
> > > libxl: debug: libxl_device.c:943:device_backend_callback: Timeout
> > > reached, initiating forced remove
> > I think this is due to interaction between frontend and backend, but I'm not an
> > expert on vtpm so I don't have further comment.
> Daniel,  are you following this issue?  --Quan
I am, but I haven't had a chance to look at what is happening with the state
changes.  There are few, if any, use cases that actually need the ability to
remove a vTPM without destroying the client domain (or the driver domain),
so I don't think this ever got tested.  I am guessing that the minios and/or
Linux driver is missing a state change step.

--
Daniel De Graaf
National Security Agency

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