Re: [Xen-devel] [PATCH 1/2] x86/VPMU: Support only versions 2 and 3 of architectural performance monitoring

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>]

Am Montag 30 November 2015, 13:38:40 schrieb Boris Ostrovsky:
> We need to have at least version 2 since it's the first version to
> support various control and status registers (such as
> MSR_CORE_PERF_GLOBAL_CTRL) that VPMU relies on always having.
> 
> With explicit testing for PMU version we can now remove CPUID model
> check.
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> ---
>  xen/arch/x86/cpu/vpmu_intel.c | 55 
> +++++++------------------------------------
>  1 file changed, 8 insertions(+), 47 deletions(-)
> 
> diff --git a/xen/arch/x86/cpu/vpmu_intel.c b/xen/arch/x86/cpu/vpmu_intel.c
> index d5ea7fe..bb4ddcc 100644
> --- a/xen/arch/x86/cpu/vpmu_intel.c
> +++ b/xen/arch/x86/cpu/vpmu_intel.c
> @@ -955,59 +955,20 @@ int vmx_vpmu_initialise(struct vcpu *v)
>  int __init core2_vpmu_init(void)
>  {
>      u64 caps;
> +    unsigned int version = 0;
>  
> -    if ( current_cpu_data.x86 != 6 )
> +    if ( current_cpu_data.cpuid_level >= 0xa )
> +        version = cpuid_eax(0xa) & 0xff;
> +    if ( (version != 2) && (version != 3) )
>      {
> -        printk(XENLOG_WARNING "VPMU: only family 6 is supported\n");
> +        printk(XENLOG_WARNING "VPMU: version %d is not supported\n", 
> version);
>          return -EINVAL;

But this means that all (newer?) processors with version=4 are not supported
even though the SDM 3B tells:
"Processors supporting architectural performance monitoring version 4 also
 supports version 1, 2, and 3, ..."

Shold we not only write a hint that version 4 capabilities are not supported
and fake this cpuid-flag for the guests to the version 3?

Dietmar.

>      }
>  
> -    switch ( current_cpu_data.x86_model )
> +    if ( current_cpu_data.x86 != 6 )
>      {
> -        /* Core2: */
> -        case 0x0f: /* original 65 nm celeron/pentium/core2/xeon, 
> "Merom"/"Conroe" */
> -        case 0x16: /* single-core 65 nm celeron/core2solo 
> "Merom-L"/"Conroe-L" */
> -        case 0x17: /* 45 nm celeron/core2/xeon "Penryn"/"Wolfdale" */
> -        case 0x1d: /* six-core 45 nm xeon "Dunnington" */
> -
> -        case 0x2a: /* SandyBridge */
> -        case 0x2d: /* SandyBridge, "Romley-EP" */
> -
> -        /* Nehalem: */
> -        case 0x1a: /* 45 nm nehalem, "Bloomfield" */
> -        case 0x1e: /* 45 nm nehalem, "Lynnfield", "Clarksfield", "Jasper 
> Forest" */
> -        case 0x2e: /* 45 nm nehalem-ex, "Beckton" */
> -
> -        /* Westmere: */
> -        case 0x25: /* 32 nm nehalem, "Clarkdale", "Arrandale" */
> -        case 0x2c: /* 32 nm nehalem, "Gulftown", "Westmere-EP" */
> -        case 0x2f: /* 32 nm Westmere-EX */
> -
> -        case 0x3a: /* IvyBridge */
> -        case 0x3e: /* IvyBridge EP */
> -
> -        /* Haswell: */
> -        case 0x3c:
> -        case 0x3f:
> -        case 0x45:
> -        case 0x46:
> -
> -        /* Broadwell */
> -        case 0x3d:
> -        case 0x4f:
> -        case 0x56:
> -
> -        /* future: */
> -        case 0x4e:
> -
> -        /* next gen Xeon Phi */
> -        case 0x57:
> -            break;
> -
> -        default:
> -            printk(XENLOG_WARNING "VPMU: Unsupported CPU model %#x\n",
> -                   current_cpu_data.x86_model);
> -            return -EINVAL;
> +        printk(XENLOG_WARNING "VPMU: only family 6 is supported\n");
> +        return -EINVAL;
>      }
>  
>      arch_pmc_cnt = core2_get_arch_pmc_count();
> 

-- 
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