On Mon, Jul 06, 2015 at 03:57:33PM +0200, Andrew Jones wrote:
> On Sat, Jul 04, 2015 at 10:26:53AM +0200, Ingo Molnar wrote:
> >
> > * Vitaly Kuznetsov <[email protected]> wrote:
> >
> > > Hypervisor callback interrupts are only accounted on Xen/Hyper-V and we
> > > detect hypervisor's type in early boot. There is no point in having
> > > always-zero HYP: line on other hypervisors or bare metal.
> > >
> > > Suggested-by: Radim Krčmář <[email protected]>
> > > Signed-off-by: Vitaly Kuznetsov <[email protected]>
> > > ---
> > > arch/x86/kernel/irq.c | 13 +++++++++----
> > > 1 file changed, 9 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
> > > index 88b36648..0c82064 100644
> > > --- a/arch/x86/kernel/irq.c
> > > +++ b/arch/x86/kernel/irq.c
> > > @@ -18,6 +18,7 @@
> > > #include <asm/mce.h>
> > > #include <asm/hw_irq.h>
> > > #include <asm/desc.h>
> > > +#include <asm/hypervisor.h>
> > >
> > > #define CREATE_TRACE_POINTS
> > > #include <asm/trace/irq_vectors.h>
> > > @@ -139,10 +140,14 @@ int arch_show_interrupts(struct seq_file *p, int
> > > prec)
> > > seq_puts(p, " Machine check polls\n");
> > > #endif
> > > #if IS_ENABLED(CONFIG_HYPERV) || defined(CONFIG_XEN)
> > > - seq_printf(p, "%*s: ", prec, "HYP");
> > > - for_each_online_cpu(j)
> > > - seq_printf(p, "%10u ", irq_stats(j)->irq_hv_callback_count);
> > > - seq_puts(p, " Hypervisor callback interrupts\n");
> > > + if (x86_hyper == &x86_hyper_ms_hyperv ||
> > > + x86_hyper == &x86_hyper_xen) {
> > > + seq_printf(p, "%*s: ", prec, "HYP");
> > > + for_each_online_cpu(j)
> > > + seq_printf(p, "%10u ",
> > > + irq_stats(j)->irq_hv_callback_count);
> > > + seq_puts(p, " Hypervisor callback interrupts\n");
> > > + }
> >
> > So I think we should simplify this to:
> >
> > if (x86_hyper) {
> > ...
> > }
> >
> > this will print the HYP line on hypervisors that don't use
> > HYPERVISOR_CALLBACK_VECTOR, but it will make it a lot more
> > self-maintaining, we
> > won't accidentally skip this line on hypervisors that start using the
> > callback
> > IRQ.
>
> This is a good point. When virt stuff creeps out, it's easy to lose track of
> it. But, I would prefer that vmware and kvm guests don't have to have a
> meaningless counter in /proc/interrupts. Also, for xen, I see that it only
> matters for x86. ARM xen builds would also have a meaningless counter. Maybe
> we should add a flags member to hypervisor_x86, and start using that in
> these types of situations.
>
Don't know why I just referred to ARM in the context of *x86*_hyper..., but
the flag idea might still be nice.
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