Re: [Xen-devel] [PATCH] NMI: continue in case of PCI SERR erros

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 25 Feb 2011, Jan Beulich wrote:
> >>> On 25.02.11 at 11:53, Stefano Stabellini 
> >>> <stefano.stabellini@xxxxxxxxxxxxx>
> wrote:
> > Memory parity error is only valid for IBM PC-AT, newer machines use
> > bit 7 (0x80) of 0x61 port for PCI SERR. While memory errors are
> > usually reported via MCE.
> > 
> > Rename the memory parity error handler to pci serr handler and
> > print a warning and continue instead of crashing.
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > 
> > ---
> > 
> > diff -r 598d1fc295b6 xen/arch/x86/traps.c
> > --- a/xen/arch/x86/traps.c  Thu Feb 24 09:33:19 2011 +0000
> > +++ b/xen/arch/x86/traps.c  Fri Feb 25 10:37:47 2011 +0000
> > @@ -3075,23 +3075,12 @@ static void nmi_dom0_report(unsigned int
> >      send_guest_trap(d, 0, TRAP_nmi);
> >  }
> >  
> > -static void mem_parity_error(struct cpu_user_regs *regs)
> > +static void pci_serr_error(struct cpu_user_regs *regs)
> >  {
> > -    switch ( opt_nmi[0] )
> > -    {
> > -    case 'd': /* 'dom0' */
> > -        nmi_dom0_report(_XEN_NMIREASON_parity_error);
> > -    case 'i': /* 'ignore' */
> > -        break;
> > -    default:  /* 'fatal' */
> > -        console_force_unlock();
> > -        printk("\n\nNMI - MEMORY ERROR\n");
> > -        fatal_trap(TRAP_nmi, regs);
> > -    }
> > +    console_force_unlock();
> > +    printk("\n\nNMI - PCI system error (SERR)\n");
> 
> Why do you remove the reporting of the event to Dom0? I'd rather
> see this part stay and the public headers getting adjusted in a
> compatible way.
> 

Because it might not have anything to do with dom0: I wrote this patch
to fix http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1744, that
is due to Xen trying to mask an MSI-X of a device assigned to a guest on
shutdown. The device seems to be in a state in which it refuses any
interactions so it sends a PCI SERR that becomes an NMI and used to
crash Xen.

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