[U-Boot] [PATCH v3 2/3] efi_loader: ARM: run EFI payloads non-secure

[Marc Zyngier]

On 13/06/18 23:41, Mark Kettenis wrote:
> If desired (and possible) switch into HYP mode or non-secure SVC mode
> before calling the entry point of an EFI application.  This allows
> U-Boot to provide a usable PSCI implementation and makes it possible
> to boot kernels into hypervisor mode using an EFI bootloader.
> 
> Based on diffs from Heinrich Schuchardt and Alexander Graf.
> 
> Signed-off-by: Mark Kettenis <kettenis at openbsd.org>
> ---
>  cmd/bootefi.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/cmd/bootefi.c b/cmd/bootefi.c
> index 707d159bac..12a6b84ce6 100644
> --- a/cmd/bootefi.c
> +++ b/cmd/bootefi.c
> @@ -20,6 +20,11 @@
>  #include <asm-generic/unaligned.h>
>  #include <linux/linkage.h>
>  
> +#ifdef CONFIG_ARMV7_NONSEC
> +#include <asm/armv7.h>
> +#include <asm/secure.h>
> +#endif
> +
>  DECLARE_GLOBAL_DATA_PTR;
>  
>  #define OBJ_LIST_NOT_INITIALIZED 1
> @@ -189,6 +194,18 @@ static efi_status_t efi_run_in_el2(EFIAPI efi_status_t (*entry)(
>  }
>  #endif
>  
> +#ifdef CONFIG_ARMV7_NONSEC
> +static efi_status_t efi_run_in_hyp(EFIAPI efi_status_t (*entry)(
> +			efi_handle_t image_handle, struct efi_system_table *st),
> +			efi_handle_t image_handle, struct efi_system_table *st)
> +{
> +	/* Enable caches again */
> +	dcache_enable();
> +
> +	return efi_do_enter(image_handle, st, entry);
> +}
> +#endif
> +
>  /* Carve out DT reserved memory ranges */
>  static efi_status_t efi_carve_out_dt_rsv(void *fdt)
>  {
> @@ -338,6 +355,21 @@ static efi_status_t do_bootefi_exec(void *efi,
>  	}
>  #endif
>  
> +#ifdef CONFIG_ARMV7_NONSEC
> +	if (armv7_boot_nonsec()) {
> +		dcache_disable();	/* flush cache before switch to HYP */
> +

What is the rational for disabling/enabling caches across the transition
to HYP? I'm sure there is a good reason, but I'd rather see it explained
here.

> +		armv7_init_nonsec();
> +		secure_ram_addr(_do_nonsec_entry)(efi_run_in_hyp,
> +				(uintptr_t)entry,
> +				(uintptr_t)loaded_image_info_obj.handle,
> +				(uintptr_t)&systab);
> +
> +		/* Should never reach here, efi exits with longjmp */
> +		while (1) { }
> +	}
> +#endif
> +
>  	ret = efi_do_enter(loaded_image_info_obj.handle, &systab, entry);
>  
>  exit:
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...