linux-kernel - Re: [PATCHv2 6/9] perf: expose perf capability to other modules.

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Date:	Mon, 07 Nov 2011 15:07:50 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Gleb Natapov <gleb@...hat.com>
Cc:	kvm@...r.kernel.org, avi@...hat.com, mtosatti@...hat.com,
	linux-kernel@...r.kernel.org, mingo@...e.hu,
	acme@...stprotocols.net
Subject: Re: [PATCHv2 6/9] perf: expose perf capability to other modules.

On Thu, 2011-11-03 at 14:33 +0200, Gleb Natapov wrote:
> @@ -1580,6 +1580,8 @@ __init int intel_pmu_init(void)
>         x86_pmu.num_counters            = eax.split.num_counters;
>         x86_pmu.cntval_bits             = eax.split.bit_width;
>         x86_pmu.cntval_mask             = (1ULL << eax.split.bit_width) - 1;
> +       x86_pmu.events_mask             = ebx;
> +       x86_pmu.events_mask_len         = eax.split.mask_length;
>  
>         /*
>          * Quirk: v2 perfmon does not report fixed-purpose events, so
> @@ -1651,6 +1653,7 @@ __init int intel_pmu_init(void)
>                          * architectural event which is often completely bogus:
>                          */
>                         intel_perfmon_event_map[PERF_COUNT_HW_BRANCH_MISSES] = 0x7f89;
> +                       x86_pmu.events_mask &= ~0x40;
>  
>                         pr_cont("erratum AAJ80 worked around, ");
>                 } 

It might make sense to introduce cpuid10_ebx or so, also I think the
removal of the branch-miss-retired event is either unwanted or
incomplete. As seen software already expects that bit to be set, even
though its known broken.

At the very least add a full ebx iteration to disable unsupported events
in the intel-v1 case.
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