Re: [Xen-devel] [PATCH v10 07/16] microcode/amd: call svm_host_osvw_init() in common code

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.09.2019 09:22, Chao Gao wrote:
> Introduce a vendor hook, .end_update_percpu, for svm_host_osvw_init().
> The hook function is called on each cpu after loading an update.
> It is a preparation for spliting out apply_microcode() from
> cpu_request_microcode().
> 
> Note that svm_host_osvm_init() should be called regardless of the
> result of loading an update.
> 
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
> Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
albeit with one further remark:

> @@ -613,29 +609,32 @@ static int cpu_request_microcode(const void *buf, 
> size_t bufsize)
>      return error;
>  }
>  
> +#ifdef CONFIG_HVM
>  static int start_update(void)
>  {
> -#if CONFIG_HVM
>      /*
> -     * We assume here that svm_host_osvw_init() will be called on each cpu 
> (from
> -     * cpu_request_microcode()).
> -     *
> -     * Note that if collect_cpu_info() returns an error then
> -     * cpu_request_microcode() will not invoked thus leaving OSVW bits not
> -     * updated. Currently though collect_cpu_info() will not fail on 
> processors
> -     * supporting OSVW so we will not deal with this possibility.
> +     * svm_host_osvw_init() will be called on each cpu by calling 
> '.end_update'
> +     * in common code.
>       */
>      svm_host_osvw_reset();
> -#endif
>  
>      return 0;
>  }
>  
> +static void end_update_percpu(void)
> +{
> +    svm_host_osvw_init();
> +}

I don't see the need for this wrapper, you could ...

> +#endif
> +
>  static const struct microcode_ops microcode_amd_ops = {
>      .cpu_request_microcode            = cpu_request_microcode,
>      .collect_cpu_info                 = collect_cpu_info,
>      .apply_microcode                  = apply_microcode,
> +#ifdef CONFIG_HVM
>      .start_update                     = start_update,
> +    .end_update_percpu                = end_update_percpu,

... use svm_host_osvw_init here directly.

Jan

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