[PATCH v2 39/44] x86: mp: Allow use of mp_run_on_cpus() without MP

[Bin Meng]

Hi Simon,

On Wed, Jul 8, 2020 at 11:34 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>
> ---
>
> (no changes since v1)
>
>  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 0f99a405bb..21fbe5bda5 100644
> --- a/arch/x86/cpu/mp_init.c
> +++ b/arch/x86/cpu/mp_init.c
> @@ -558,7 +558,7 @@ 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;

I believe this change was already squashed into the part B series,
hence this does not apply on top of u-boot-x86/master.

>  }
>
>  /**
> @@ -718,9 +718,6 @@ 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_READY))
> -               return -ENXIO;
> -
>         ret = get_bsp(&dev, &num_cpus);
>         if (ret < 0)
>                 return log_msg_ret("bsp", ret);
> @@ -730,6 +727,13 @@ int mp_run_on_cpus(int cpu_select, mp_run_func func, void *arg)
>                 func(arg);
>         }
>
> +       if (!(gd->flags & GD_FLG_SMP_READY)) {
> +               /* Allow use of this function on the BSP only */
> +               if (cpu_select == MP_SELECT_BSP || !cpu_select)
> +                       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)

Reviewed-by: Bin Meng <bmeng.cn at gmail.com>

Regards,
Bin