[PATCH v2] stm32mp: Reserve OPTEE area in EFI memory map

[Patrick DELAUNAY]

Hi,

On 4/22/24 17:06, Patrice Chotard wrote:
> Since commit 7b78d6438a2b3 ("efi_loader: Reserve unaccessible memory")
> memory region above ram_top is tagged in EFI memory map as
> EFI_BOOT_SERVICES_DATA.
> In case of STM32MP1/STM32MP13 platforms, above ram_top, there is one
> reserved-memory region tagged "no-map" dedicated to OP-TEE :
>   _ addr=de000000 size=2000000 for stm32mp157x-dkx and stm32mp135f-dk
>   _ addr=fe000000 size=2000000 for stm32mp157c-ev1
>
> Before booting kernel, EFI memory map is first built, the OPTEE region is
> tagged as EFI_BOOT_SERVICES_DATA and when reserving LMB, the tag LMB_NONE
> is used.
>
> Then after, the LMB are completed by boot_fdt_add_mem_rsv_regions()
> which try to add again the same OPTEE region (addr=de000000 size=2000000
> in case of stm32mp157x-dkx / stm32mp135f-dk or addr=fe000000 size=2000000
> in case for stm2mp157c-ev1)
> but now with LMB_NOMAP tag which produces the following error message :
>
>   _ for stm32mp157x-dkx / stm32mp135f-dk :
>    "ERROR: reserving fdt memory region failed (addr=de000000 size=2000000 flags=4)"
>
>   _ for stm32mp157c-ev1 :
>    "ERROR: reserving fdt memory region failed (addr=fe000000 size=2000000 flags=4)"
>
> To avoid this, OPTEE area shouldn't be used by EFI, so we need to mark
> it as reserved.
>
> Signed-off-by: Patrice Chotard <patrice.chotard at foss.st.com>
>
> ---
>
> Changes in v2:
>   _ update commit message by adding information about memory area
>     dedicated for OPTEE for various STM32MP1/STM32MP13 boards.
>
>   arch/arm/mach-stm32mp/dram_init.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
>
> diff --git a/arch/arm/mach-stm32mp/dram_init.c b/arch/arm/mach-stm32mp/dram_init.c
> index fb1208fc5d5..f67f54f2ae0 100644
> --- a/arch/arm/mach-stm32mp/dram_init.c
> +++ b/arch/arm/mach-stm32mp/dram_init.c
> @@ -7,6 +7,7 @@
>   
>   #include <common.h>
>   #include <dm.h>
> +#include <efi_loader.h>
>   #include <image.h>
>   #include <init.h>
>   #include <lmb.h>
> @@ -75,3 +76,14 @@ phys_addr_t board_get_usable_ram_top(phys_size_t total_size)
>   
>   	return reg + size;
>   }
> +
> +void efi_add_known_memory(void)
> +{
> +	if (IS_ENABLED(CONFIG_EFI_LOADER))
> +		/*
> +		 * Memory over ram_top is reserved to OPTEE.
> +		 * Declare to EFI only memory area below ram_top
> +		 */
> +		efi_add_memory_map(gd->ram_base, gd->ram_top - gd->ram_base,
> +				   EFI_CONVENTIONAL_MEMORY);
> +}

It seen like a temporary workaround after commit 7b78d6438a2b3
("efi_loader: Reserve unaccessible memory") to avoid warnings.

And it is working because in the default memory mapping
OP-TEE base address == RAM_TOP and the rest of memory is
used by OP-TEE tagged "no map" (protected by firewall)


Reviewed-by: Patrick Delaunay <patrick.delaunay at foss.st.com>

FYI: workaround because  the memory above ram_top is
      "already occupied by firmware" =
      and it is OP-TEE for STM32MP2 platform.

     For me the LMB type used by EFI in not correct for OP-TEE usage region
     with "no-map" tag in device tree=  see boot_fdt_add_mem_rsv_regions()
     for linux DT parsing

     and we have no way to indicated this LMB tag= LMB_NOMAP with EFI stack
     (with enum efi_memory_type ?)


     EFI_BOOT_SERVICES_DATA => doesn't means NOMAP flag for LMB....
     so something is missing in EFI side like EFI_BOOT_NOMAP  to be used in board
     implementation of efi_add_known_memory() ?


Thanks
Patrick