Re: [PATCH] x86/hvm/viridian: set shutdown_code in response to CrashNotify

[Paul Durrant <Paul.Durrant@citrix.com>]

> -----Original Message-----
> From: Andrew Cooper
> Sent: 06 September 2018 16:33
> To: Paul Durrant <Paul.Durrant@citrix.com>; xen-devel@lists.xenproject.org
> Cc: Jan Beulich <jbeulich@suse.com>
> Subject: Re: [PATCH] x86/hvm/viridian: set shutdown_code in response to
> CrashNotify
> 
> On 06/09/18 16:32, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: Xen-devel [mailto:xen-devel-bounces@lists.xenproject.org] On
> Behalf
> >> Of Paul Durrant
> >> Sent: 23 August 2018 09:38
> >> To: Andrew Cooper <Andrew.Cooper3@citrix.com>; xen-
> >> devel@lists.xenproject.org
> >> Cc: Jan Beulich <jbeulich@suse.com>
> >> Subject: Re: [Xen-devel] [PATCH] x86/hvm/viridian: set shutdown_code
> in
> >> response to CrashNotify
> >>
> >>> -----Original Message-----
> >>> From: Andrew Cooper
> >>> Sent: 16 August 2018 10:40
> >>> To: Paul Durrant <Paul.Durrant@citrix.com>; xen-
> >> devel@lists.xenproject.org
> >>> Cc: Jan Beulich <jbeulich@suse.com>
> >>> Subject: Re: [PATCH] x86/hvm/viridian: set shutdown_code in response
> to
> >>> CrashNotify
> >>>
> >>> On 10/08/18 16:59, Paul Durrant wrote:
> >>>>> -----Original Message-----
> >>>>> From: Andrew Cooper
> >>>>> Sent: 10 August 2018 16:57
> >>>>> To: Paul Durrant <Paul.Durrant@citrix.com>; xen-
> >>> devel@lists.xenproject.org
> >>>>> Cc: Jan Beulich <jbeulich@suse.com>
> >>>>> Subject: Re: [PATCH] x86/hvm/viridian: set shutdown_code in
> response
> >>> to
> >>>>> CrashNotify
> >>>>>
> >>>>> On 10/08/18 16:43, Paul Durrant wrote:
> >>>>>> When Windows writes the CrashNotify bit in the CRASH_CTL MSR
> then
> >>> we
> >>>>> know
> >>>>>> it is crashing, so set the domain shutdown code appropriately.
> >>>>>>
> >>>>>> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> >>>>>> ---
> >>>>>> Cc: Jan Beulich <jbeulich@suse.com>
> >>>>>> Cc: Andrew Cooper <andrew.cooper3@citrix.com>
> >>>>>> ---
> >>>>>>  xen/arch/x86/hvm/viridian.c | 4 ++++
> >>>>>>  1 file changed, 4 insertions(+)
> >>>>>>
> >>>>>> diff --git a/xen/arch/x86/hvm/viridian.c
> b/xen/arch/x86/hvm/viridian.c
> >>>>>> index 486065182c..294cf486cc 100644
> >>>>>> --- a/xen/arch/x86/hvm/viridian.c
> >>>>>> +++ b/xen/arch/x86/hvm/viridian.c
> >>>>>> @@ -645,6 +645,10 @@ int wrmsr_viridian_regs(uint32_t idx,
> uint64_t
> >>> val)
> >>>>>>          if ( !ctl.u.CrashNotify )
> >>>>>>              break;
> >>>>>>
> >>>>>> +        spin_lock(&d->shutdown_lock);
> >>>>>> +        d->shutdown_code = SHUTDOWN_crash;
> >>>>>> +        spin_unlock(&d->shutdown_lock);
> >>>>> How does the domain eventually shut down?
> >>>> I assume it shuts down when the guest writes to the PIIX.
> >>>>
> >>>>>   It feels slightly odd to have
> >>>>> a shutdown code before the domain has finished executing code.
> >>>>>
> >>>> That's the norm. The PV drivers (if they are installed) set it via a
> schedop.
> >>> This just makes sure it is set even if the PV drivers aren't there.
> >>>
> >>> What happens if the user has configured windows to reboot after a
> crash?
> >>>
> >> That's exactly what this is trying to fix. Without the patch a VM without PV
> >> drivers will appear to just shut down (because nothing will set the
> shutdown
> >> code to anything else) so the actions-after-crash will not take effect.
> >>
> > Ping? Are you ok with the patch now?
> 
> Lol - I was literally just trying to find it.  I'll commit it in a moment.
> 

:-)

> ~Andrew
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