Re: [kvm-unit-tests PATCH v3 08/18] arm64: efi: Improve device tree discovery

["Paluri, PavanKumar" <papaluri@amd.com>]

Hi,

On 3/5/2024 10:46 AM, Andrew Jones wrote:
> Check the device tree GUID when the environment variable is missing,
> which allows directly loading the unit test with QEMU's '-kernel'
> command line parameter, which is much faster than putting the test
> in the EFI file system and then running it from the UEFI shell.
> 
> Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
> Signed-off-by: Andrew Jones <andrew.jones@linux.dev>
> ---
>  lib/efi.c       | 19 ++++++++++++-------
>  lib/linux/efi.h |  2 ++
>  2 files changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/lib/efi.c b/lib/efi.c
> index d94f0fa16fc0..4d1126b4a64e 100644
> --- a/lib/efi.c
> +++ b/lib/efi.c
> @@ -6,13 +6,13 @@
>   *
>   * SPDX-License-Identifier: LGPL-2.0-or-later
>   */
> -
> -#include "efi.h"
> +#include <libcflat.h>
>  #include <argv.h>
> -#include <stdlib.h>
>  #include <ctype.h>
> -#include <libcflat.h>
> +#include <stdlib.h>
>  #include <asm/setup.h>
> +#include "efi.h"
> +#include "libfdt/libfdt.h"
>  
>  /* From lib/argv.c */
>  extern int __argc, __envc;
> @@ -288,13 +288,18 @@ static void *efi_get_fdt(efi_handle_t handle, struct efi_loaded_image_64 *image)
>  	efi_char16_t var[] = ENV_VARNAME_DTBFILE;
>  	efi_char16_t *val;
>  	void *fdt = NULL;
> -	int fdtsize;
> +	int fdtsize = 0;
>  
>  	val = efi_get_var(handle, image, var);
> -	if (val)
> +	if (val) {
>  		efi_load_image(handle, image, &fdt, &fdtsize, val);
> +		if (fdtsize == 0)
> +			return NULL;
> +	} else if (efi_get_system_config_table(DEVICE_TREE_GUID, &fdt) != EFI_SUCCESS) {
> +		return NULL;
> +	}
>  
> -	return fdt;
> +	return fdt_check_header(fdt) == 0 ? fdt : NULL;

The call to fdt_check_header() seems to be breaking x86 based UEFI
tests. I have tested it with .x86/efi/run ./x86/smptest.efi

Thanks,
Pavan
>  }
>  
>  efi_status_t efi_main(efi_handle_t handle, efi_system_table_t *sys_tab)
> diff --git a/lib/linux/efi.h b/lib/linux/efi.h
> index 410f0b1a0da1..92d798f79767 100644
> --- a/lib/linux/efi.h
> +++ b/lib/linux/efi.h
> @@ -66,6 +66,8 @@ typedef guid_t efi_guid_t;
>  #define ACPI_TABLE_GUID EFI_GUID(0xeb9d2d30, 0x2d88, 0x11d3, 0x9a, 0x16, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
>  #define ACPI_20_TABLE_GUID EFI_GUID(0x8868e871, 0xe4f1, 0x11d3,  0xbc, 0x22, 0x00, 0x80, 0xc7, 0x3c, 0x88, 0x81)
>  
> +#define DEVICE_TREE_GUID EFI_GUID(0xb1b621d5, 0xf19c, 0x41a5,  0x83, 0x0b, 0xd9, 0x15, 0x2c, 0x69, 0xaa, 0xe0)
> +
>  #define LOADED_IMAGE_PROTOCOL_GUID EFI_GUID(0x5b1b31a1, 0x9562, 0x11d2,  0x8e, 0x3f, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b)
>  
>  typedef struct {