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

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(-)

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