Re: [Xen-devel] [PATCH v3 05/15] x86: implement get hw info flow for MBA

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Sep 05, 2017 at 05:32:27PM +0800, Yi Sun wrote:
> This patch implements get HW info flow for MBA including its callback
> function and sysctl interface.
> 
> Signed-off-by: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx>
> ---
> v3:
>     - replace 'PSR_VAL_TYPE_MBA' to 'PSR_TYPE_MBA_THRTL'.
>       (suggested by Roger Pau Monné)
> v2:
>     - use 'XEN_SYSCTL_PSR_MBA_LINEAR' to set MBA feature HW info.
>       (suggested by Chao Peng)
> v1:
>     - sort 'PSR_INFO_IDX_' macros as feature.
>       (suggested by Chao Peng)
>     - rename 'PSR_INFO_IDX_MBA_LINEAR' to 'PSR_INFO_IDX_MBA_FLAG'.
>     - rename 'linear' in 'struct mba_info' to 'flags' for future extension.
>       (suggested by Chao Peng)
> ---
>  xen/arch/x86/psr.c          | 17 ++++++++++++++++-
>  xen/arch/x86/sysctl.c       | 19 +++++++++++++++++++
>  xen/include/asm-x86/psr.h   |  2 ++
>  xen/include/public/sysctl.h |  8 ++++++++
>  4 files changed, 45 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
> index 10776d2..0486d2d 100644
> --- a/xen/arch/x86/psr.c
> +++ b/xen/arch/x86/psr.c
> @@ -263,6 +263,10 @@ static enum psr_feat_type psr_type_to_feat_type(enum 
> psr_type type)
>          feat_type = FEAT_TYPE_L2_CAT;
>          break;
>  
> +    case PSR_TYPE_MBA_THRTL:
> +        feat_type = FEAT_TYPE_MBA;
> +        break;
> +
>      default:
>          ASSERT_UNREACHABLE();
>      }
> @@ -491,7 +495,18 @@ static const struct feat_props l2_cat_props = {
>  static bool mba_get_feat_info(const struct feat_node *feat,
>                                uint32_t data[], unsigned int array_len)
>  {
> -    return false;
> +    if ( array_len != PSR_INFO_ARRAY_SIZE )
> +        return false;
> +
> +    data[PSR_INFO_IDX_COS_MAX] = feat->cos_max;
> +    data[PSR_INFO_IDX_MBA_THRTL_MAX] = feat->mba.thrtl_max;
> +
> +    if ( feat->mba.linear )
> +        data[PSR_INFO_IDX_MBA_FLAG] |= XEN_SYSCTL_PSR_ALLOC_MBA_LINEAR;
> +    else
> +        data[PSR_INFO_IDX_MBA_FLAG] &= ~XEN_SYSCTL_PSR_ALLOC_MBA_LINEAR;

This branch of the if shouldn't be needed...

> +
> +    return true;
>  }
>  
>  static void mba_write_msr(unsigned int cos, uint32_t val,
> diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c
> index 1d3dbd0..4634cad 100644
> --- a/xen/arch/x86/sysctl.c
> +++ b/xen/arch/x86/sysctl.c
> @@ -214,6 +214,25 @@ long arch_do_sysctl(
>              break;
>          }
>  
> +        case XEN_SYSCTL_PSR_ALLOC_get_mba_info:
> +        {
> +            ret = psr_get_info(sysctl->u.psr_alloc.target,
> +                               PSR_TYPE_MBA_THRTL, data, ARRAY_SIZE(data));

... because data should be initialized, ie:

uint32_t data[PSR_INFO_ARRAY_SIZE] = { 0 };

So that we don't leak stack data in the sysctl.

Thanks, Roger.

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