Re: [Xen-devel] [PATCH] Intel/vpmu: Use Intel VPMU quirk on all family 6 processors

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 05/09/2013 04:34 PM, Boris Ostrovsky wrote:
> Currently only a few Intel models have VPMU workaround turned on. It
> appears, however, that this issue exists on more models than what is
> covered by check_pmc_quirk(). Since we don't know exactly which cpus
> are affected we should turn this workaround on for all family 6
> processors.
Haitao,

A few weeks ago we had an email thread about this issue
(http://lists.xen.org/archives/html/xen-devel/2013-03/msg02618.html)
Did you have a chance to clarify with your HW folks what this is?

We kept hitting this on various models which is why I am suggesting this
patch (and I think it should be considered for 4.3).

-boris


> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> ---
>   xen/arch/x86/hvm/vmx/vpmu_core2.c | 16 +++++-----------
>   1 file changed, 5 insertions(+), 11 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/vmx/vpmu_core2.c 
> b/xen/arch/x86/hvm/vmx/vpmu_core2.c
> index 9f152b4..15b2036 100644
> --- a/xen/arch/x86/hvm/vmx/vpmu_core2.c
> +++ b/xen/arch/x86/hvm/vmx/vpmu_core2.c
> @@ -65,8 +65,7 @@
>   #define PMU_FIXED_WIDTH_MASK     (((1 << PMU_FIXED_WIDTH_BITS) -1) << 
> PMU_FIXED_WIDTH_SHIFT)
>   
>   /*
> - * QUIRK to workaround an issue on Nehalem processors currently seen
> - * on family 6 cpus E5520 (model 26) and X7542 (model 46).
> + * QUIRK to workaround an issue on various family 6 cpus.
>    * The issue leads to endless PMC interrupt loops on the processor.
>    * If the interrupt handler is running and a pmc reaches the value 0, this
>    * value remains forever and it triggers immediately a new interrupt after
> @@ -79,15 +78,10 @@ bool_t __read_mostly is_pmc_quirk;
>   
>   static void check_pmc_quirk(void)
>   {
> -    u8 family = current_cpu_data.x86;
> -    u8 cpu_model = current_cpu_data.x86_model;
> -    is_pmc_quirk = 0;
> -    if ( family == 6 )
> -    {
> -        if ( cpu_model == 47 || cpu_model == 46 || cpu_model == 42 ||
> -             cpu_model == 26 )
> -            is_pmc_quirk = 1;
> -    }
> +    if ( current_cpu_data.x86 == 6 )
> +        is_pmc_quirk = 1;
> +    else
> +        is_pmc_quirk = 0;
>   }
>   
>   static int core2_get_pmc_count(void);

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