[PATCH v8 4/8] efi_loader: add a function to remove memory from the EFI map

[Heinrich Schuchardt]

On 12.03.25 09:54, Sughosh Ganu wrote:
> From: Ilias Apalodimas <ilias.apalodimas at linaro.org>
>
> With upcoming changes supporting pmem nodes, we need to remove the
> pmem area from the EFI memory map. Add a function to do that.
>
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
> Changes since V7: None
>
>   include/efi_loader.h        | 18 ++++++++++++
>   lib/efi_loader/efi_memory.c | 56 ++++++++++++++++++++++++++-----------
>   2 files changed, 58 insertions(+), 16 deletions(-)
>
> diff --git a/include/efi_loader.h b/include/efi_loader.h
> index e9c10819ba2..c20c98c6476 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -878,6 +878,24 @@ efi_status_t efi_get_memory_map(efi_uintn_t *memory_map_size,
>   /* Adds a range into the EFI memory map */
>   efi_status_t efi_add_memory_map(u64 start, u64 size, int memory_type);
>
> +/**
> + * efi_update_memory_map() - update the memory map by adding/removing pages
> + *
> + * @start:			start address, must be a multiple of
> + *				EFI_PAGE_SIZE
> + * @pages:			number of pages to add
> + * @memory_type:		type of memory added
> + * @overlap_conventional:	region may only overlap free(conventional)
> + *				memory
> + * @remove:			remove memory map
> + * Return:			status code
> + */
> +efi_status_t efi_update_memory_map(u64 start, u64 pages, int memory_type,
> +				   bool overlap_conventional, bool remove);

Why do we have so many functions that are all doing nearly the same thing:

* efi_map_update_notify()
* efi_update_memory_map()
* efi_remove_memory_map()
* efi_add_memory_map_pg()

I start failing to understand when to use which. This is getting as
gruesome as LMB.

Can't we have a single exported function with a properly defined
interface to cover all use cases?

Best regards

Heinrich

> +
> +/* Remove memory from the EFI memory map */
> +efi_status_t efi_remove_memory_map(u64 start, u64 size, int memory_type);
> +
>   /* Called by board init to initialize the EFI drivers */
>   efi_status_t efi_driver_init(void);
>   /* Called when a block device is added */
> diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
> index 6d00b186250..3fec40b6de5 100644
> --- a/lib/efi_loader/efi_memory.c
> +++ b/lib/efi_loader/efi_memory.c
> @@ -258,7 +258,7 @@ static s64 efi_mem_carve_out(struct efi_mem_list *map,
>   }
>
>   /**
> - * efi_add_memory_map_pg() - add pages to the memory map
> + * efi_update_memory_map() - update the memory map by adding/removing pages
>    *
>    * @start:			start address, must be a multiple of
>    *				EFI_PAGE_SIZE
> @@ -266,12 +266,11 @@ static s64 efi_mem_carve_out(struct efi_mem_list *map,
>    * @memory_type:		type of memory added
>    * @overlap_conventional:	region may only overlap free(conventional)
>    *				memory
> + * @remove:			remove memory map
>    * Return:			status code
>    */
> -static
> -efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
> -				   int memory_type,
> -				   bool overlap_conventional)
> +efi_status_t efi_update_memory_map(u64 start, u64 pages, int memory_type,
> +				   bool overlap_conventional, bool remove)
>   {
>   	struct efi_mem_list *lmem;
>   	struct efi_mem_list *newlist;
> @@ -279,9 +278,9 @@ efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
>   	uint64_t carved_pages = 0;
>   	struct efi_event *evt;
>
> -	EFI_PRINT("%s: 0x%llx 0x%llx %d %s\n", __func__,
> +	EFI_PRINT("%s: 0x%llx 0x%llx %d %s %s\n", __func__,
>   		  start, pages, memory_type, overlap_conventional ?
> -		  "yes" : "no");
> +		  "yes" : "no", remove ? "remove" : "add");
>
>   	if (memory_type >= EFI_MAX_MEMORY_TYPE)
>   		return EFI_INVALID_PARAMETER;
> @@ -364,7 +363,10 @@ efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
>   	}
>
>   	/* Add our new map */
> -        list_add_tail(&newlist->link, &efi_mem);
> +	if (!remove)
> +		list_add_tail(&newlist->link, &efi_mem);
> +	else
> +		free(newlist);
>
>   	/* And make sure memory is listed in descending order */
>   	efi_mem_sort();
> @@ -401,7 +403,29 @@ efi_status_t efi_add_memory_map(u64 start, u64 size, int memory_type)
>   	pages = efi_size_in_pages(size + (start & EFI_PAGE_MASK));
>   	start &= ~EFI_PAGE_MASK;
>
> -	return efi_add_memory_map_pg(start, pages, memory_type, false);
> +	return efi_update_memory_map(start, pages, memory_type, false, false);
> +}
> +
> +/**
> + * efi_remove_memory_map() - remove memory area to the memory map
> + *
> + * @start:		start address of the memory area
> + * @size:		length in bytes of the memory area
> + * @memory_type:	type of memory removed
> + *
> + * Return:		status code
> + *
> + * This function automatically aligns the start and size of the memory area
> + * to EFI_PAGE_SIZE.
> + */
> +efi_status_t efi_remove_memory_map(u64 start, u64 size, int memory_type)
> +{
> +	u64 pages;
> +
> +	pages = efi_size_in_pages(size + (start & EFI_PAGE_MASK));
> +	start &= ~EFI_PAGE_MASK;
> +
> +	return efi_update_memory_map(start, pages, memory_type, false, true);
>   }
>
>   /**
> @@ -502,7 +526,7 @@ efi_status_t efi_allocate_pages(enum efi_allocate_type type,
>
>   	efi_addr = (u64)(uintptr_t)map_sysmem(addr, 0);
>   	/* Reserve that map in our memory maps */
> -	ret = efi_add_memory_map_pg(efi_addr, pages, memory_type, true);
> +	ret = efi_update_memory_map(efi_addr, pages, memory_type, true, false);
>   	if (ret != EFI_SUCCESS) {
>   		/* Map would overlap, bail out */
>   		lmb_free_flags(addr, (u64)pages << EFI_PAGE_SHIFT, flags);
> @@ -823,8 +847,8 @@ static void add_u_boot_and_runtime(void)
>   		       uboot_stack_size) & ~EFI_PAGE_MASK;
>   	uboot_pages = ((uintptr_t)map_sysmem(gd->ram_top - 1, 0) -
>   		       uboot_start + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;
> -	efi_add_memory_map_pg(uboot_start, uboot_pages, EFI_BOOT_SERVICES_CODE,
> -			      false);
> +	efi_update_memory_map(uboot_start, uboot_pages, EFI_BOOT_SERVICES_CODE,
> +			      false, false);
>   #if defined(__aarch64__)
>   	/*
>   	 * Runtime Services must be 64KiB aligned according to the
> @@ -842,8 +866,8 @@ static void add_u_boot_and_runtime(void)
>   	runtime_end = (uintptr_t)__efi_runtime_stop;
>   	runtime_end = (runtime_end + runtime_mask) & ~runtime_mask;
>   	runtime_pages = (runtime_end - runtime_start) >> EFI_PAGE_SHIFT;
> -	efi_add_memory_map_pg(runtime_start, runtime_pages,
> -			      EFI_RUNTIME_SERVICES_CODE, false);
> +	efi_update_memory_map(runtime_start, runtime_pages,
> +			      EFI_RUNTIME_SERVICES_CODE, false, false);
>   }
>
>   int efi_memory_init(void)
> @@ -878,11 +902,11 @@ int efi_map_update_notify(phys_addr_t addr, phys_size_t size,
>   	pages = efi_size_in_pages(size + (efi_addr & EFI_PAGE_MASK));
>   	efi_addr &= ~EFI_PAGE_MASK;
>
> -	status = efi_add_memory_map_pg(efi_addr, pages,
> +	status = efi_update_memory_map(efi_addr, pages,
>   				       op == LMB_MAP_OP_RESERVE ?
>   				       EFI_BOOT_SERVICES_DATA :
>   				       EFI_CONVENTIONAL_MEMORY,
> -				       false);
> +				       false, false);
>   	if (status != EFI_SUCCESS) {
>   		log_err("LMB Map notify failure %lu\n",
>   			status & ~EFI_ERROR_MASK);