[PATCH v2 19/25] x86: mtrr: Update MTRRs on all CPUs

[Bin Meng]

Hi Simon,

On Mon, Jun 15, 2020 at 1:00 AM Simon Glass <sjg at chromium.org> wrote:
>
> When the boot CPU MTRRs are updated, perform the same update on all other
> CPUs so they are kept in sync.
>
> This avoids kernel warnings about mismatched MTRRs.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> Reviewed-by: Wolfgang Wallner <wolfgang.wallner at br-automation.com>
> ---
>
> Changes in v2:
> - Rename function to mtrr_write_all()
>
>  arch/x86/cpu/mtrr.c | 57 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 57 insertions(+)
>
> diff --git a/arch/x86/cpu/mtrr.c b/arch/x86/cpu/mtrr.c
> index c9b4e7d06e..5c567551e5 100644
> --- a/arch/x86/cpu/mtrr.c
> +++ b/arch/x86/cpu/mtrr.c
> @@ -74,10 +74,61 @@ void mtrr_read_all(struct mtrr_info *info)
>         }
>  }
>
> +void mtrr_write_all(struct mtrr_info *info)
> +{
> +       struct mtrr_state state;
> +       int i;
> +
> +       for (i = 0; i < MTRR_COUNT; i++) {
> +               mtrr_open(&state, true);
> +               wrmsrl(MTRR_PHYS_BASE_MSR(i), info->mtrr[i].base);
> +               wrmsrl(MTRR_PHYS_MASK_MSR(i), info->mtrr[i].mask);
> +               mtrr_close(&state, true);
> +       }
> +}
> +
> +static void write_mtrrs(void *arg)
> +{
> +       struct mtrr_info *info = arg;
> +
> +       mtrr_write_all(info);
> +}
> +
> +static void read_mtrrs(void *arg)
> +{
> +       struct mtrr_info *info = arg;
> +
> +       mtrr_read_all(info);
> +}
> +
> +/**
> + * mtrr_copy_to_aps() - Copy the MTRRs from the boot CPU to other CPUs
> + *
> + * @return 0 on success, -ve on failure
> + */
> +static int mtrr_copy_to_aps(void)
> +{
> +       struct mtrr_info info;
> +       int ret;
> +
> +       ret = mp_run_on_cpus(MP_SELECT_BSP, read_mtrrs, &info);
> +       if (ret == -ENXIO)
> +               return 0;
> +       else if (ret)
> +               return log_msg_ret("bsp", ret);
> +
> +       ret = mp_run_on_cpus(MP_SELECT_APS, write_mtrrs, &info);
> +       if (ret)
> +               return log_msg_ret("bsp", ret);
> +
> +       return 0;
> +}
> +
>  int mtrr_commit(bool do_caches)
>  {
>         struct mtrr_request *req = gd->arch.mtrr_req;
>         struct mtrr_state state;
> +       int ret;
>         int i;
>
>         debug("%s: enabled=%d, count=%d\n", __func__, gd->arch.has_mtrr,
> @@ -99,6 +150,12 @@ int mtrr_commit(bool do_caches)
>         mtrr_close(&state, do_caches);
>         debug("mtrr done\n");
>
> +       if (gd->flags & GD_FLG_RELOC) {
> +               ret = mtrr_copy_to_aps();
> +               if (ret)
> +                       return log_msg_ret("copy", ret);
> +       }
> +
>         return 0;
>  }
>
> --

We need to find a place where mtrr in BSP is duplicated in AP.

Currently this is done in init_cache_f_r() but at that time SMP is not
ready yet.

Regards,
Bin