Messages in this thread | | | From | Michael Ellerman <> | Subject | Re: [1/1] powerpc/hv-24x7: Check support before registering PMU | Date | Mon, 11 May 2015 20:26:15 +1000 (AEST) |
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On Thu, 2015-30-04 at 03:04:51 UTC, Sukadev Bhattiprolu wrote: > We currently try to register the 24x7 PMU unconditionally. Not all > Power systems support 24x7 counters (eg: Power7). On these systems > we get a backtrace during boot when trying to register the 24x7 PMU. > > Check if the hypervisor supports 24x7 counters before attempting to > register the 24x7 PMU.
The concept is good, but ..
> diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c > index ec2eb20..19a59a3 100644 > --- a/arch/powerpc/perf/hv-24x7.c > +++ b/arch/powerpc/perf/hv-24x7.c > @@ -1268,12 +1268,44 @@ static struct pmu h_24x7_pmu = { > .read = h_24x7_event_read, > }; > > +/* > + * Return 1 if we can access the 24x7 counter catalog from the hypervisor. > + * Return 0 otherwise. > + */ > +static int hv_has_24x7(void)
bool please
> +{ > + int page_size = 4096; > + unsigned long hret; > + void *page; > + struct hv_24x7_catalog_page_0 *page_0; > + > + page_0 = kmalloc(page_size*2, GFP_KERNEL); > + if (!page_0) > + return 0; > + > + /* buffer for catalog needs to be 4K-aligned */ > + page = (void *)((long)page_0 & (~page_size-1)) + page_size; > + hret = h_get_24x7_catalog_page(page, 0, 0); > + kfree(page_0);
It shouldn't need to be this complicated.
You should just be able to do the hcall with bogus args and if you get H_FUNCTION then 24x7 is not supported.
cheers
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