Re: [Xen-devel] Bisected Xen-unstable: "Segment register inaccessible for d1v0" when starting HVM guest on intel

["Wu, Feng" <feng.wu@xxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Thursday, July 03, 2014 9:21 PM
> To: Wu, Feng
> Cc: Andrew Cooper; Sander Eikelenboom; xen-devel@xxxxxxxxxxxxxxxxxxxx
> Subject: RE: [Xen-devel] Bisected Xen-unstable: "Segment register inaccessible
> for d1v0" when starting HVM guest on intel
> 
> >>> On 03.07.14 at 15:04, <feng.wu@xxxxxxxxx> wrote:
> >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> And as Andrew emphasized, raising a fault in response to a failure
> >> here is out of question (the only two options considering this is
> >> asynchronous would be #MC or a failsafe callback, neither of which
> >> really fit the purpose). Nevertheless it would be rather desirable to
> >> have a way to tell the guest about the dropped write. We've got
> >> a field in struct arch_vcpu_info that we could leverage for this,
> >> requiring the guest to actively poll if it cares about finding out (to
> >> avoid the polling this could further be combined with a new
> >> per-vCPU vIRQ, or by defining another XEN_NMIREASON_* value
> >> and delivering the notification via NMI).
> >
> > I am not familiar with these related code actually, I try to get some
> > findings in the code, but seems no good news. So maybe I have some
> > basic questions here:
> > 1. What is the purpose of 'struct arch_vcpu_info arch'?
> > 2. Do you mean I can use the member 'unsigned long pad' of it to tell
> > the guest about the dropped write.
> > 3. What information about the dropped write should be sent to guest?
> > 4. When guests will poll the information?
> > 5. Can vIRQ be used for HVM guest? Is there an existing example in the
> > current code?
> 
> With this many questions I don't think there's much point in you doing
> the notification part; why don't you just start without notification,
> adding of which is an enhancement only anyway?

Yes, I think this is a better at the current stage. Will do this soon! Thanks
a lot!

Thanks,
Feng

> 
> Jan
> 


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