[RFC PATCH] arm: EFI: Disallow EFI bootmgr when providing PSCI

[Simon Glass]

On Fri, 22 Jan 2021 at 05:05, Andre Przywara <andre.przywara at arm.com> wrote:
>
> When "bootefi bootmgr" is run, it switches the CPU into non-secure
> state. This breaks platforms like 32-bit Allwinner boards that rely on
> running in secure state until late in the process, when they install
> the PSCI handler in secure memory and drop into non-secure state.
> They hang just before entering the kernel, after the "Starting the
> kernel" message.
>
> Commit f3866909e350 ("distro_bootcmd: call EFI bootmgr even without
> having /EFI/boot") changed the order of EFI probing, so the EFI bootmgr
> is now *always* run, resulting in the default distro boot commands now
> *always* failing, even in the total absence of any UEFI directories or
> boot files.
>
> So use the newly added build option to disable the EFI bootmgr, which
> makes those boards boot again using the distro boot commands.
> Explicitly calling "bootefi bootmgr" still breaks the boot, though.
>
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> Reported-by: Jernej Skrabec <jernej.skrabec at siol.net>
> ---
> Hi,
>
> the above is the result of my analysis, happy to stand corrected in
> case I missed something. I know that this is not a proper solution,
> but it's an effective stop-gap measure to fix all those boards. It looks
> like a proper solution would either be:
> - Let the EFI bootmgr run in the current security state.
> - Install the PSCI handlers early in U-Boot.
>
> Both solutions sound rather involved, so probably require more time.
> But we need to fix this breakage now.
>
> Cheers,
> Andre
>
>  lib/efi_loader/Kconfig | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Simon Glass <sjg at chromium.org>