Re: [Xen-devel] [PATCH v4 05/15] x86: implement get hw info flow for MBA

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

On Sat, Sep 23, 2017 at 09:48:14AM +0000, 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>
> ---
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
> 
> v4:
>     - remove 'ALLOC_' from macro names.
>       (suggested by Roger Pau Monné)
>     - initialize 'data[PSR_INFO_ARRAY_SIZE]' to 0 to prevent to leak stack 
> data.
>       (suggested by Roger Pau Monné)
> 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          | 15 ++++++++++++++-
>  xen/arch/x86/sysctl.c       | 21 ++++++++++++++++++++-
>  xen/include/asm-x86/psr.h   |  2 ++
>  xen/include/public/sysctl.h |  8 ++++++++
>  4 files changed, 44 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
> index e2f8fd0..1d0a215 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();
>      }
> @@ -486,7 +490,16 @@ 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 )

Should this be an ASSERT maybe? I don't see how array_len can be !=
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_MBA_LINEAR;
> +
> +    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 9dee163..b2f8efa 100644
> --- a/xen/arch/x86/sysctl.c
> +++ b/xen/arch/x86/sysctl.c
> @@ -174,7 +174,7 @@ long arch_do_sysctl(
>      case XEN_SYSCTL_psr_alloc:
>          switch ( sysctl->u.psr_alloc.cmd )
>          {
> -            uint32_t data[PSR_INFO_ARRAY_SIZE];
> +            uint32_t data[PSR_INFO_ARRAY_SIZE] = {0};

I would rather do "{ 0 };" or "{ };" (note the spaces around the 0).

Thanks, Roger.

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