Re: [Qemu-arm] [PATCH v2 4/5] arm: boot: Add secure_board_setup flag

[Peter Maydell]

On 30 October 2015 at 05:34, Peter Crosthwaite
<address@hidden> wrote:
> Add a flag that when set, will cause the primary CPU to start in secure
> mode, even if the overall boot in non-secure. This is useful for when

"is non-secure".

> there is a board-setup blob that needs to run from secure mode, but
> device and secondary CPU init should still be done as-normal for a non-
> secure boot.
>
> Signed-off-by: Peter Crosthwaite <address@hidden>
> ---
>
>  hw/arm/boot.c        | 3 ++-
>  include/hw/arm/arm.h | 6 ++++++
>  2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> index b0879a5..6680d45 100644
> --- a/hw/arm/boot.c
> +++ b/hw/arm/boot.c
> @@ -495,7 +495,8 @@ static void do_cpu_reset(void *opaque)
>                  }
>
>                  /* Set to non-secure if not a secure boot */
> -                if (!info->secure_boot) {
> +                if (!info->secure_boot &&
> +                    (cs != first_cpu || !info->secure_board_setup)) {
>                      /* Linux expects non-secure state */
>                      env->cp15.scr_el3 |= SCR_NS;
>                  }
> diff --git a/include/hw/arm/arm.h b/include/hw/arm/arm.h
> index 9217b70..60dc919 100644
> --- a/include/hw/arm/arm.h
> +++ b/include/hw/arm/arm.h
> @@ -97,6 +97,12 @@ struct arm_boot_info {
>      hwaddr board_setup_addr;
>      void (*write_board_setup)(ARMCPU *cpu,
>                                const struct arm_boot_info *info);
> +
> +    /* If set, the board specific loader/setup blob will be run from secure
> +     * mode, regardless of secure_boot. The blob becomes responsible for
> +     * changing to non-secure state if implementing a non-secure boot
> +     */
> +    bool secure_board_setup;
>  };

I thought you were planning to have the generic code do the
S->NS transition; but I guess it works better in the board
code (we have to go up into Monitor and back down again, right?)

Is it an error for the board to set secure_board_setup if
the CPU doesn't have EL3? (if so, worth mentioning in this
comment; maybe assert?)

thanks
-- PMM