[PATCH v1 38/43] x86: mp: Allow use of mp_run_on_cpus() without MP

[Bin Meng]

Hi Simon,

On Mon, Jun 15, 2020 at 11:58 AM Simon Glass <sjg at chromium.org> wrote:
>
> At present if MP is not enabled (e.g. booting from coreboot) the 'mtrr'
> command does not work correctly. It is not easy to make it work for all
> CPUs, since coreboot has halted them and we would need to start them up
> again, but it is easy enough to make them work on the boot CPU.
>
> Update the code to avoid assuming that the MP init routine has completed,
> so that this can work.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
>  arch/x86/cpu/mp_init.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/cpu/mp_init.c b/arch/x86/cpu/mp_init.c
> index ef33a38017..c0ae24686e 100644
> --- a/arch/x86/cpu/mp_init.c
> +++ b/arch/x86/cpu/mp_init.c
> @@ -454,7 +454,7 @@ static int get_bsp(struct udevice **devp, int *cpu_countp)
>         if (cpu_countp)
>                 *cpu_countp = ret;
>
> -       return dev->req_seq;
> +       return dev->req_seq >= 0 ? dev->req_seq : 0;
>  }
>
>  static struct mp_callback *read_callback(struct mp_callback **slot)
> @@ -589,9 +589,6 @@ int mp_run_on_cpus(int cpu_select, mp_run_func func, void *arg)
>         int num_cpus;
>         int ret;
>
> -       if (!(gd->flags & GD_FLG_SMP_INIT))
> -               return -ENXIO;
> -
>         ret = get_bsp(&dev, &num_cpus);
>         if (ret < 0)
>                 return log_msg_ret("bsp", ret);
> @@ -601,6 +598,13 @@ int mp_run_on_cpus(int cpu_select, mp_run_func func, void *arg)
>                 func(arg);
>         }
>
> +       if (!(gd->flags & GD_FLG_SMP_INIT)) {
> +               /* Allow use of this function on the BSP only */
> +               if (cpu_select == MP_SELECT_BSP || !cpu_select)

This assumes 0 is the BSP cpu number?

> +                       return 0;
> +               return -ENXIO;
> +       }
> +
>         /* Allow up to 1 second for all APs to finish */
>         ret = run_ap_work(&lcb, dev, num_cpus, 1000 /* ms */);
>         if (ret)
> --

Regards,
Bin