[PATCH v5] Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic

Sunil Muthuswamy sunilmut at microsoft.com
Mon Jun 11 18:50:35 UTC 2018



> -----Original Message-----
> From: KY Srinivasan
> Sent: Monday, June 11, 2018 11:39 AM
> To: Sunil Muthuswamy <sunilmut at microsoft.com>; Haiyang Zhang
> <haiyangz at microsoft.com>
> Cc: devel at linuxdriverproject.org; Stephen Hemminger
> <sthemmin at microsoft.com>
> Subject: RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> over Hyper-V during panic
> 
> 
> 
> > -----Original Message-----
> > From: Sunil Muthuswamy
> > Sent: Monday, June 11, 2018 10:44 AM
> > To: KY Srinivasan <kys at microsoft.com>; Haiyang Zhang
> > <haiyangz at microsoft.com>
> > Cc: devel at linuxdriverproject.org; Stephen Hemminger
> > <sthemmin at microsoft.com>
> > Subject: RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> > over Hyper-V during panic
> >
> >
> >
> > > -----Original Message-----
> > > From: KY Srinivasan
> > > Sent: Sunday, June 10, 2018 2:54 PM
> > > To: Sunil Muthuswamy <sunilmut at microsoft.com>; Haiyang Zhang
> > > <haiyangz at microsoft.com>
> > > Cc: devel at linuxdriverproject.org; Stephen Hemminger
> > > <sthemmin at microsoft.com>
> > > Subject: RE: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> > > over Hyper-V during panic
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Sunil Muthuswamy
> > > > Sent: Friday, June 8, 2018 11:39 AM
> > > > To: Haiyang Zhang <haiyangz at microsoft.com>
> > > > Cc: devel at linuxdriverproject.org; Sunil Muthuswamy
> > > > <sunilmut at microsoft.com>; KY Srinivasan <kys at microsoft.com>;
> > Stephen
> > > > Hemminger <sthemmin at microsoft.com>
> > > > Subject: [PATCH v5] Drivers: HV: Send one page worth of kmsg dump
> > over
> > > > Hyper-V during panic
> > > >
> > > > In the VM mode on Hyper-V, currently, when the kernel panics, an
> error
> > > > code and few register values are populated in an MSR and the
> Hypervisor
> > > > notified. This information is collected on the host. The amount of
> > > > information currently collected is found to be limited and not very
> > > > actionable. To gather more actionable data, such as stack trace, the
> > > > proposal is to write one page worth of kmsg data on an allocated page
> > > > and the Hypervisor notified of the page address through the MSR.
> > > >
> 
> Snip.
> 
> > > >  /*
> > > >   * vmbus_bus_init -Main vmbus driver initialization routine.
> > > > @@ -1065,6 +1136,38 @@ static int vmbus_bus_init(void)
> > > >  	 * Only register if the crash MSRs are available
> > > >  	 */
> > > >  	if (ms_hyperv.misc_features &
> > > > HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
> > > > +		u64 hyperv_crash_ctl;
> > > > +		if (!hv_ctl_table_hdr) {
> > > When vmus_bus_init is invoked, would hv_ctl_table_hdr  ever be
> > > Non-NULL?
> Ping.
Missed this somehow. It should not be. Will fix this as well in the next version.
> 
> Snip.
> 
> Regards,
> 
> K. Y


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