RE: [PATCH 0/4] x86/Hyper-V: Unload vmbus channel in hv panic callback

[Michael Kelley <mikelley@microsoft.com>]

From: Vitaly Kuznetsov <vkuznets@redhat.com>  Sent: Thursday, March 19, 2020 1:04 AM
> 
> Michael Kelley <mikelley@microsoft.com> writes:
> 
> >> > --- a/drivers/hv/vmbus_drv.c
> >> > +++ b/drivers/hv/vmbus_drv.c
> >> > @@ -53,9 +53,12 @@ static int hyperv_panic_event(struct notifier_block *nb,
> unsigned
> >> long val,
> >> >  {
> >> >  	struct pt_regs *regs;
> >> >
> >> > -	regs = current_pt_regs();
> >> > +	vmbus_initiate_unload(true);
> >> >
> >> > -	hyperv_report_panic(regs, val);
> >> > +	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
> >>
> >> With Michael's effors to make code in drivers/hv arch agnostic, I think
> >> we need a better, arch-neutral way.
> >
> > Vitaly -- could you elaborate on what part is not arch-neutral?  I don't see
> > a problem.  ms_hyperv and the misc_features field exist for both the x86
> > and ARM64 code branches.  It turns out the particular bit for
> > GUEST_CRASH_MSR_AVAILABLE is different on the two architectures, but
> > the compiler will do the right thing.
> >
> 
> Ah, apologies, missed the fact that we also call it
> 'HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE' - I have to admit I was confused
> by the 'MSR' part. We can probably rename this to something like
> HV_FEATURE_GUEST_CRASH_REGS_AVAILABLE - but not as part of the series.
> 

Good point.  Agreed.

Michael