[PATCH v5 6/6] blkmap: pass information on ISO image to the OS
Tobias Waldekranz
tobias at waldekranz.com
Thu Feb 27 21:00:45 CET 2025
On tor, feb 27, 2025 at 16:45, Sughosh Ganu <sughosh.ganu at linaro.org> 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>
> ---
If a v6 is needed for some other reason (you seemed to indicate that),
then see my small comments below. Either way:
Reviewed-by: Tobias Waldekranz <tobias at waldekranz.com>
> Changes since V4:
> * Reword the commit message
> * Add a helper function blkmap_get_preserved_pmem_slice()
> * Add a function pmem_node_efi_memmap_setup() for pmem node and EFI
> memmap related setup
>
> boot/image-fdt.c | 7 ++++++
> drivers/block/blkmap.c | 43 +++++++++++++++++++++++++++++++++++++
> include/blkmap.h | 17 +++++++++++++++
> include/efi.h | 13 +++++++++++
> lib/efi_loader/efi_helper.c | 37 +++++++++++++++++++++++++++++++
> 5 files changed, 117 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..c9e0a3a6eea 100644
> --- a/drivers/block/blkmap.c
> +++ b/drivers/block/blkmap.c
> @@ -498,6 +498,49 @@ err:
> return err;
> }
>
> +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;
> +
> + 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) || !cb)
> + 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) {
> + log_err("Failed to setup pmem node for addr %#lx, size %#x\n",
> + addr, size);
IMO, this function should not make any assumptions about what the
callback is doing. If an error is encountered, then the callback should
decide if it warrants an entry in the log or not.
> + return -1;
And the non-zero return value (`err`) of the callback should be passed
verbatim back to our caller here, in case it wants to discriminate
between different kinds of errors.
> + }
> + }
> + }
> +
> + return 0;
> +
> +}
> +
> int blkmap_destroy(struct udevice *dev)
> {
> int err;
> diff --git a/include/blkmap.h b/include/blkmap.h
> index 754d8671b01..89bd2b65fba 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
> + * @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, -1 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 04b2efc4a3b..675f3efa79a 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 +681,39 @@ 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)
> + 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);
...i.e. here is the code that knows what the callback is doing, so it
can choose to emit the log message - without imposing that behavior on
any other users of the iterator.
> +}
> --
> 2.34.1
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