[PATCH v8 8/8] blkmap: pass information on ISO image to the OS

[Heinrich Schuchardt]

On 12.03.25 09:54, Sughosh Ganu wrote:
> The EFI HTTP boot puts the ISO installer image at some location in
> memory. Information about this image has to be passed on to the OS
> kernel, which is done by adding a persistent memory(pmem) node to the
> devicetree(DT) that is passed to the OS. The OS kernel then gets
> information about the presence of this ISO image and proceeds with the
> installation.
> 
> In U-Boot, this ISO image gets mounted as a memory mapped blkmap
> device slice, with the 'preserve' attribute. Add a helper function
> which iterates through all such slices, and invokes a callback. The
> callback adds the pmem node to the DT and removes the corresponding
> memory region from the EFI memory map. Invoke this helper function as
> part of the DT fixup which happens before booting the OS.
> 
> Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> Reviewed-by: Tobias Waldekranz <tobias at waldekranz.com>
> ---
> Changes since V7:
> * Fix checkpatch errors in blkmap.c and efi_helper.c
> 
>   boot/image-fdt.c            |  7 ++++++
>   drivers/block/blkmap.c      | 44 +++++++++++++++++++++++++++++++++++++
>   include/blkmap.h            | 17 ++++++++++++++
>   include/efi.h               | 13 +++++++++++
>   lib/efi_loader/efi_helper.c | 39 ++++++++++++++++++++++++++++++++
>   5 files changed, 120 insertions(+)
> 
> diff --git a/boot/image-fdt.c b/boot/image-fdt.c
> index 9d1598b1a93..8f718ad29f6 100644
> --- a/boot/image-fdt.c
> +++ b/boot/image-fdt.c
> @@ -11,6 +11,7 @@
>   #include <command.h>
>   #include <fdt_support.h>
>   #include <fdtdec.h>
> +#include <efi.h>
>   #include <env.h>
>   #include <errno.h>
>   #include <image.h>
> @@ -649,6 +650,12 @@ int image_setup_libfdt(struct bootm_headers *images, void *blob, bool lmb)
>   	if (!ft_verify_fdt(blob))
>   		goto err;
>   
> +	if (CONFIG_IS_ENABLED(BLKMAP) && CONFIG_IS_ENABLED(EFI_LOADER)) {
> +		fdt_ret = fdt_efi_pmem_setup(blob);
> +		if (fdt_ret)
> +			goto err;
> +	}
> +
>   	/* after here we are using a livetree */
>   	if (!of_live_active() && CONFIG_IS_ENABLED(EVENT)) {
>   		struct event_ft_fixup fixup;
> diff --git a/drivers/block/blkmap.c b/drivers/block/blkmap.c
> index eefed615998..5f7602d0405 100644
> --- a/drivers/block/blkmap.c
> +++ b/drivers/block/blkmap.c
> @@ -498,6 +498,50 @@ err:
>   	return err;
>   }
>   

Please, add the missing documentation.
https://docs.kernel.org/doc-guide/kernel-doc.html#function-documentation

> +static bool blkmap_mem_preserve_slice(struct blkmap_slice *bms)
> +{
> +	return (bms->attr & (BLKMAP_SLICE_MEM | BLKMAP_SLICE_PRESERVE)) ==
> +		(BLKMAP_SLICE_MEM | BLKMAP_SLICE_PRESERVE);
> +}
> +
> +int blkmap_get_preserved_pmem_slice(int (*cb)(void *ctx, ulong addr,
> +					      u32 size), void *ctx)
> +{
> +	int ret;
> +	u32 size;
> +	ulong addr;
> +	struct udevice *dev;
> +	struct uclass *uc;
> +	struct blkmap *bm;
> +	struct blkmap_mem *bmm;
> +	struct blkmap_slice *bms;
> +	struct blk_desc *bd;
> +
> +	if (!cb) {
> +		log_debug("%s: No callback passed to the function\n", __func__);
> +		return 0;
> +	}
> +
> +	uclass_id_foreach_dev(UCLASS_BLKMAP, dev, uc) {
> +		bm = dev_get_plat(dev);
> +		bd = dev_get_uclass_plat(bm->blk);
> +
> +		list_for_each_entry(bms, &bm->slices, node) {
> +			if (!blkmap_mem_preserve_slice(bms))
> +				continue;
> +
> +			bmm = container_of(bms, struct blkmap_mem, slice);
> +			addr = (ulong)(uintptr_t)bmm->addr;
> +			size = (u32)bms->blkcnt << bd->log2blksz;
> +			ret = cb(ctx, addr, size);
> +			if (ret)
> +				return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>   int blkmap_destroy(struct udevice *dev)
>   {
>   	int err;
> diff --git a/include/blkmap.h b/include/blkmap.h
> index 754d8671b01..30ce80c0ad1 100644
> --- a/include/blkmap.h
> +++ b/include/blkmap.h
> @@ -7,6 +7,7 @@
>   #ifndef _BLKMAP_H
>   #define _BLKMAP_H
>   
> +#include <blk.h>
>   #include <dm/lists.h>
>   
>   /**
> @@ -104,4 +105,20 @@ int blkmap_destroy(struct udevice *dev);
>   int blkmap_create_ramdisk(const char *label, ulong image_addr, ulong image_size,
>   			  struct udevice **devp);
>   
> +/**
> + * blkmap_get_preserved_pmem_slice() - Look for memory mapped preserved slice
> + * @cb: Callback function to call for the blkmap slice

Please, describe in sufficient detail for a developer who has to 
implement such a callback function what information should be provided 
by the function.

All arguments of cb and its return value need to be described.

Best regards

Heinrich

> + * @ctx: Argument to be passed to the callback function
> + *
> + * The function is used to iterate through all the blkmap slices, looking
> + * specifically for memory mapped blkmap mapping which has been
> + * created with the preserve attribute. The function looks for such slices
> + * with the relevant attributes and then calls the callback function which
> + * then does additional configuration as needed.
> + *
> + * Return: 0 on success, negative error on failure
> + */
> +int blkmap_get_preserved_pmem_slice(int (*cb)(void *ctx, ulong addr,
> +					      u32 size), void *ctx);
> +
>   #endif	/* _BLKMAP_H */
> diff --git a/include/efi.h b/include/efi.h
> index d005cb6181e..f9bbb175c3a 100644
> --- a/include/efi.h
> +++ b/include/efi.h
> @@ -705,4 +705,17 @@ static inline bool efi_use_host_arch(void)
>    */
>   int efi_get_pxe_arch(void);
>   
> +/**
> + * fdt_efi_pmem_setup() - Pmem setup in DT and EFI memory map
> + * @fdt: Devicetree to add the pmem nodes to
> + *
> + * Iterate through all the blkmap devices, look for BLKMAP_MEM devices,
> + * and add pmem nodes corresponding to the blkmap slice to the
> + * devicetree along with removing the corresponding region from the
> + * EFI memory map.
> + *
> + * Returns: 0 on success, negative error on failure
> + */
> +int fdt_efi_pmem_setup(void *fdt);
> +
>   #endif /* _LINUX_EFI_H */
> diff --git a/lib/efi_loader/efi_helper.c b/lib/efi_loader/efi_helper.c
> index 37e5859741f..62772a0d747 100644
> --- a/lib/efi_loader/efi_helper.c
> +++ b/lib/efi_loader/efi_helper.c
> @@ -5,6 +5,7 @@
>   
>   #define LOG_CATEGORY LOGC_EFI
>   
> +#include <blkmap.h>
>   #include <bootm.h>
>   #include <env.h>
>   #include <image.h>
> @@ -680,3 +681,41 @@ out:
>   
>   	return ret;
>   }
> +
> +/**
> + * pmem_node_efi_memmap_setup() - Add pmem node and tweak EFI memmap
> + * @fdt: The devicetree to which pmem node is added
> + * @addr: start address of the pmem node
> + * @size: size of the memory of the pmem node
> + *
> + * The function adds the pmem node to the device-tree along with removing
> + * the corresponding region from the EFI memory map. Used primarily to
> + * pass the information of a RAM based ISO image to the OS.
> + *
> + * Return: 0 on success, -ve value on error
> + */
> +static int pmem_node_efi_memmap_setup(void *fdt, ulong addr, u32 size)
> +{
> +	int ret;
> +	efi_status_t status;
> +
> +	ret = fdt_fixup_pmem_region(fdt, addr, size);
> +	if (ret) {
> +		log_err("Failed to setup pmem node for addr %#lx, size %#x, err %d\n",
> +			addr, size, ret);
> +		return ret;
> +	}
> +
> +	status = efi_remove_memory_map(addr, size,
> +				       EFI_CONVENTIONAL_MEMORY);
> +	if (status != EFI_SUCCESS)
> +		return -1;
> +
> +	return 0;
> +}
> +
> +int fdt_efi_pmem_setup(void *fdt)
> +{
> +	return blkmap_get_preserved_pmem_slice(pmem_node_efi_memmap_setup,
> +					       fdt);
> +}