linux-kernel - Re: [PATCH] perf/x86: Disable uncore on virtualized CPU.

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Message-ID: <CAOJsxLEPh4PH-jV-S7jPZExg0r_YsqL+2tHErRtA7bpygbP6iQ@mail.gmail.com>
Date:	Tue, 21 Aug 2012 15:55:19 +0300
From:	Pekka Enberg <penberg@...nel.org>
To:	"Yan, Zheng" <zheng.z.yan@...el.com>
Cc:	a.p.zijlstra@...llo.nl, eranian@...gle.com, mingo@...e.hu,
	andi@...stfloor.org, avi@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf/x86: Disable uncore on virtualized CPU.

On Tue, Aug 21, 2012 at 12:08 PM, Yan, Zheng <zheng.z.yan@...el.com> wrote:
> From: "Yan, Zheng" <zheng.z.yan@...el.com>
>
> Initializing uncore PMU on virtualized CPU may hang the kernel.
> This is because kvm does not emulate the entire hardware. Thers
> are lots of uncore related MSRs, making kvm enumerate them all
> is a non-trival task. So just disable uncore on virtualized CPU.
>
> Signed-off-by: Yan, Zheng <zheng.z.yan@...el.com>
> ---
>  arch/x86/kernel/cpu/perf_event_intel_uncore.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
> index 0a55710..2f005ba 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
> @@ -2898,6 +2898,9 @@ static int __init intel_uncore_init(void)
>         if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
>                 return -ENODEV;
>
> +       if (cpu_has_hypervisor)
> +               return -ENODEV;
> +
>         ret = uncore_pci_init();
>         if (ret)
>                 goto fail;

Tested-by: Pekka Enberg <penberg@...nel.org>
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