Re: [PATCH 14/35] efi: Locate all block devices in the app

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

On 9/8/21 3:33 PM, Simon Glass wrote:
> When starting the app, locate all block devices and make them available
> to U-Boot. This allows listing partitions and accessing files in
> filesystems.
>
> EFI also has the concept of 'disks', meaning boot media. For now, this
> is not obviously useful in U-Boot, but add code to at least locate these.
> This can be expanded later as needed.

UEFI firmware handles with the EFI_BLOCK_IO_PROTOCOL for raw access to
disks and partitions. It further provides the
EFI_SIMPLE_FILE_SYSTEM_PROTOCOL on these handles to access files on
formatted media.

>
> Signed-off-by: Simon Glass <sjg@chromium.org>
> ---
>
>   include/efi.h     |  15 ++++++
>   include/efi_api.h |  15 ++++++
>   lib/efi/efi_app.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 149 insertions(+)
>
> diff --git a/include/efi.h b/include/efi.h
> index 0ec5913ddd1..c0fddf7f6cd 100644
> --- a/include/efi.h
> +++ b/include/efi.h
> @@ -529,4 +529,19 @@ void efi_putc(struct efi_priv *priv, const char ch);
>    */
>   int efi_info_get(enum efi_entry_t type, void **datap, int *sizep);
>
> +/**
> + * efi_bind_block() - bind a new block device to an EFI device
> + *
> + * Binds a new top-level EFI_MEDIA device as well as a child block device so
> + * that the block device can be accessed in U-Boot.
> + *
> + * The device can then be accessed using 'part list efi 0', 'fat ls efi 0:1',
> + * for example, just like any other interface type.
> + *
> + * @handle: handle of the controller on which this driver is installed
> + * @blkio: block io protocol proxied by this driver
> + * @return 0 if OK, -ve on error
> + */
> +int efi_bind_block(efi_handle_t handle, struct efi_block_io *blkio);
> +
>   #endif /* _LINUX_EFI_H */
> diff --git a/include/efi_api.h b/include/efi_api.h
> index c8f959bb720..0e88b3e5dbe 100644
> --- a/include/efi_api.h
> +++ b/include/efi_api.h
> @@ -1994,4 +1994,19 @@ struct efi_firmware_management_protocol {
>   			const u16 *package_version_name);
>   };
>
> +#define EFI_DISK_IO_PROTOCOL_GUID	\
> +	EFI_GUID(0xce345171, 0xba0b, 0x11d2, 0x8e, 0x4f, \
> +		 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b)
> +
> +struct efi_disk {
> +	u64 revision;
> +	efi_status_t (EFIAPI *read_disk)(struct efi_disk *this, u32 media_id,
> +					 u64 offset, efi_uintn_t buffer_size,
> +					 void *buffer);
> +
> +	efi_status_t (EFIAPI *write_disk)(struct efi_disk *this, u32 media_id,
> +					  u64 offset, efi_uintn_t buffer_size,
> +					  void *buffer);
> +};
> +
>   #endif
> diff --git a/lib/efi/efi_app.c b/lib/efi/efi_app.c
> index f61665686c5..9ba48517422 100644
> --- a/lib/efi/efi_app.c
> +++ b/lib/efi/efi_app.c
> @@ -21,6 +21,9 @@
>   #include <efi.h>
>   #include <efi_api.h>
>   #include <sysreset.h>
> +#include <dm/device-internal.h>
> +#include <dm/lists.h>
> +#include <dm/root.h>
>
>   DECLARE_GLOBAL_DATA_PTR;
>
> @@ -46,6 +49,33 @@ int efi_info_get(enum efi_entry_t type, void **datap, int *sizep)
>   	return -ENOSYS;
>   }
>
> +/**
> + * Create a block device so U-Boot can access an EFI device
> + *
> + * @handle:	EFI handle to bind
> + * @blkio:	block io protocol
> + * Return:	0 = success
> + */
> +int efi_bind_block(efi_handle_t handle, struct efi_block_io *blkio)
> +{
> +	struct efi_media_plat plat;
> +	struct udevice *dev;
> +	char name[18];
> +	int ret;
> +
> +	plat.handle = handle;
> +	plat.blkio = blkio;
> +	ret = device_bind(dm_root(), DM_DRIVER_GET(efi_media), "efi_media",
> +			  &plat, ofnode_null(), &dev);
> +	if (ret)
> +		return log_msg_ret("bind", ret);
> +
> +	snprintf(name, sizeof(name), "efi_media_%x", dev_seq(dev));
> +	device_set_name(dev, name);
> +
> +	return 0;
> +}
> +
>   static efi_status_t setup_memory(struct efi_priv *priv)
>   {
>   	struct efi_boot_services *boot = priv->boot;
> @@ -105,6 +135,95 @@ static void free_memory(struct efi_priv *priv)
>   	global_data_ptr = NULL;
>   }
>
> +static int setup_disks(void)
> +{
> +	/* This is not fully implemented yet */
> +	return 0;
> +
> +	efi_guid_t efi_disk_guid = EFI_DISK_IO_PROTOCOL_GUID;
> +	struct efi_boot_services *boot = efi_get_boot();
> +	struct efi_disk *disk;
> +	int ret;
> +
> +	if (!boot)
> +		return log_msg_ret("sys", -ENOSYS);
> +	ret = boot->locate_protocol(&efi_disk_guid, NULL, (void **)&disk);
> +	if (ret)
> +		return log_msg_ret("prot", -ENOTSUPP);
> +
> +	return 0;
> +}
> +
> +static int setup_block(void)
> +{
> +	efi_guid_t efi_blkio_guid = EFI_BLOCK_IO_PROTOCOL_GUID;
> +	efi_guid_t efi_devpath_guid = EFI_DEVICE_PATH_PROTOCOL_GUID;
> +	struct efi_boot_services *boot = efi_get_boot();
> +	struct efi_block_io *blkio;
> +	struct efi_device_path device_path;
> +	efi_handle_t handle[100];
> +	efi_uintn_t buf_size;
> +	int num_handles;
> +	int ret, i;
> +
> +	if (!boot)
> +		return log_msg_ret("sys", -ENOSYS);
> +
> +	buf_size = sizeof(handle);
> +	ret = boot->locate_handle(BY_PROTOCOL, &efi_blkio_guid, NULL,
> +				  &buf_size, handle);

You could use LocateHandleBuffer() here which will allocate enough
memory for all matching handles.

> +	if (ret)
> +		return log_msg_ret("loc", -ENOTSUPP);
> +
> +	num_handles = buf_size / sizeof(efi_handle_t);
> +	log_info("Found %d EFI handles\n", num_handles);
> +
> +	for (i = 0; i < num_handles; i++) {
> +		ret = boot->handle_protocol(handle[i], &efi_devpath_guid,
> +					    (void **)&device_path);


Why do you read the devicepath if you don't use it?

> +		if (ret) {
> +			log_warning("- devpath %d failed (ret=%d)\n", i, ret);
> +			continue;
> +		}

Here some analysis of devicepaths and installed protocols is missing to
find out which of the handles represents a block device and which
represents a partition:

If the last devicepath node is type 4 , Media Device Path with SubType 1
Hard Drive and the partition number is non-zero it is a partition.

If the devicepath without the last node relates to a handle with the
EFI_BLOCK_IO_PROTOCOL, this also indicates that the current handle is
for a partition.

Best regards

Heinrich

> +
> +		ret = boot->handle_protocol(handle[i], &efi_blkio_guid,
> +					    (void **)&blkio);
> +		if (ret) {
> +			log_warning("- blkio %d failed (ret=%d)\n", i, ret);
> +			continue;
> +		}
> +
> +		ret = efi_bind_block(handle[i], blkio);
> +		if (ret) {
> +			log_warning("- blkio bind %d failed (ret=%d)\n", i, ret);
> +			continue;
> +		}
> +	}
> +	if (ret)
> +		return log_msg_ret("prot", -ENOTSUPP);
> +
> +	return 0;
> +}
> +
> +int dm_scan_other(bool pre_reloc_only)
> +{
> +	if (gd->flags & GD_FLG_RELOC) {
> +		int ret;
> +
> +		/* Find all block devices and setup EFI devices for them */
> +		ret = setup_block();
> +		if (ret)
> +			return ret;
> +
> +		/* Not needed at present, but could be useful one day? */
> +		ret = setup_disks();
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
>   /**
>    * efi_main() - Start an EFI image
>    *
>