Re: [Xen-devel] [PATCH v17 14/23] x86/VPMU: Initialize VPMUs with __initcall

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 01/30/2015 09:54 AM, Jan Beulich wrote:
> > > > On 05.01.15 at 22:44, <boris.ostrovsky@xxxxxxxxxx> wrote:
> > --- a/xen/arch/x86/hvm/vpmu.c
> > +++ b/xen/arch/x86/hvm/vpmu.c
> > @@ -497,3 +497,39 @@ long do_xenpmu_op(int op, 
> > XEN_GUEST_HANDLE_PARAM(xen_pmu_params_t) arg)
> >
> >       return ret;
> >   }
> > +
> > +static int __init vpmu_init(void)
> > +{
> > +    int vendor = current_cpu_data.x86_vendor;
> > +
> > +    if ( vpmu_mode == XENPMU_MODE_OFF )
> > +    {
> > +        printk(XENLOG_INFO "VPMU: disabled\n");
> > +        return 0;
> > +    }
> > +
> > +    switch ( vendor )
> > +    {
> > +    case X86_VENDOR_AMD:
> > +        if ( amd_vpmu_init() )
> > +           vpmu_mode = XENPMU_MODE_OFF;
> > +        break;
> > +    case X86_VENDOR_INTEL:
> > +        if ( core2_vpmu_init() )
> > +           vpmu_mode = XENPMU_MODE_OFF;
> > +        break;
> > +    default:
> > +        printk(XENLOG_WARNING "VPMU: Unknown CPU vendor: %d\n", vendor);
> > +        vpmu_mode = XENPMU_MODE_OFF;
> > +        break;
> return 0;
>
> (i.e. avoid printing another message below)
>
> > +    }
> > +
> > +    if ( vpmu_mode == XENPMU_MODE_OFF )
> > +        printk(XENLOG_WARNING "VPMU: Disabling due to initialization error\n");
> We repeatedly find that not printing at least a vague indication of
> what went wrong makes problem analysis quite a bit more difficult.
> It won't cost much to include the actual error code here.

The actual error is printed by the architectural code (i.e. 
amd_vpmu_init()/core2_vpmu_init()).

-boris



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