Re: [PATCH 03/16] efi: memory: use the lmb API's for allocating and freeing memory

On Sat, 14 Sept 2024 at 20:35, Heinrich Schuchardt xypron.glpk@gmx.de wrote:

On 9/5/24 10:27, Sughosh Ganu wrote:

...

Use the LMB API's for allocating and freeing up memory. With this, the LMB module becomes the common backend for managing non U-Boot image memory that might be requested by other modules.

Signed-off-by: Sughosh Ganu sughosh.ganu@linaro.org

lib/efi_loader/Kconfig | 1 + lib/efi_loader/efi_memory.c | 74 ++++++++++--------------------------- 2 files changed, 21 insertions(+), 54 deletions(-)

diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig index 6ffefa9103..911d4c6bbe 100644 --- a/lib/efi_loader/Kconfig +++ b/lib/efi_loader/Kconfig @@ -18,6 +18,7 @@ config EFI_LOADER select DM_EVENT select EVENT_DYNAMIC select LIB_UUID

• select LMB
  imply PARTITION_UUIDS
  select REGEX
  imply FAT
  

diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c index c6f1dd0945..90e07ed6a2 100644 --- a/lib/efi_loader/efi_memory.c +++ b/lib/efi_loader/efi_memory.c @@ -9,6 +9,7 @@

#include <efi_loader.h> #include <init.h> +#include <lmb.h> #include <log.h> #include <malloc.h> #include <mapmem.h> @@ -432,53 +433,6 @@ static efi_status_t efi_check_allocated(u64 addr, bool must_be_allocated) return EFI_NOT_FOUND; }

-/**

• • efi_find_free_memory() - find free memory pages
• • @len: size of memory area needed
• • @max_addr: highest address to allocate
• • Return: pointer to free memory area or 0
• */

-static uint64_t efi_find_free_memory(uint64_t len, uint64_t max_addr) -{

• struct efi_mem_list *lmem;
  

• /*
  

•  * Prealign input max address, so we simplify our matching
  

•  * logic below and can just reuse it as return pointer.
  

•  */
  

• max_addr &= ~EFI_PAGE_MASK;
  

• list_for_each_entry(lmem, &efi_mem, link) {
  

•         struct efi_mem_desc *desc = &lmem->desc;
  

•         uint64_t desc_len = desc->num_pages << EFI_PAGE_SHIFT;
  

•         uint64_t desc_end = desc->physical_start + desc_len;
  

•         uint64_t curmax = min(max_addr, desc_end);
  

•         uint64_t ret = curmax - len;
  

•         /* We only take memory from free RAM */
  

•         if (desc->type != EFI_CONVENTIONAL_MEMORY)
  

•                 continue;
  

•         /* Out of bounds for max_addr */
  

•         if ((ret + len) > max_addr)
  

•                 continue;
  

•         /* Out of bounds for upper map limit */
  

•         if ((ret + len) > desc_end)
  

•                 continue;
  

•         /* Out of bounds for lower map limit */
  

•         if (ret < desc->physical_start)
  

•                 continue;
  

•         /* Return the highest address in this map within bounds */
  

•         return ret;
  

• }
  

• return 0;
  

-}

• /**
  • efi_allocate_pages - allocate memory pages

@@ -493,6 +447,7 @@ efi_status_t efi_allocate_pages(enum efi_allocate_type type, efi_uintn_t pages, uint64_t *memory) { u64 len;

• uint flags;
  efi_status_t ret;
  uint64_t addr;
  
  

@@ -508,33 +463,35 @@ efi_status_t efi_allocate_pages(enum efi_allocate_type type, (len >> EFI_PAGE_SHIFT) != (u64)pages) return EFI_OUT_OF_RESOURCES;

• flags = LMB_NOOVERWRITE | LMB_NONOTIFY;
  

In the EFI context we should use LMB notification to notify the EFI_EVENT_GROUP_MEMORY_MAP_CHANGE event and update the memory map.

Not sure if I am understanding your comment right, but what is happening here is that the EFI subsystem is requesting LMB for memory. And the reason why we have a flag LMB_NONOTIFY, is to prevent a circular chain of LMB then notifying EFI of a change to it's memory map.

See chapter 7.1.2 EFI_BOOT_SERVICES.CreateEventEx() in the UEFI specification.

...

  switch (type) {
  case EFI_ALLOCATE_ANY_PAGES:
          /* Any page */

•         addr = efi_find_free_memory(len, -1ULL);
  

•         addr = (u64)lmb_alloc_flags(len, EFI_PAGE_SIZE, flags);
  

On ARM64 we must ensure that "all 4KiB pages in the 64KiB page ... use identical ARM Memory Page Attributes". I cannot see how LMB implements this.

If you are referring to arm memory attributes, this is not being handled by the current EFI memory code as well. If this is to be handled, that needs to be taken up as a separate task -- I am not sure if U-Boot even has support in the form of any API's where memory regions can be configured for different memory attributes.

See chapter 2.3.6 AArch64 Platforms in the UEFI specification.

If you pass the EFI memory type to LMB and store it there, we can avoid duplication of the memory map and we can implement the 64 KiB pages logic in LMB.

Okay, that would mean mixing up EFI code in the LMB module. Again, not sure if this comes under the purview of the goal of this series, which is to ensure that EFI memory does not trample over that allocated by LMB. Also, thinking a bit more on this, if we are to address aspects like memory attributes etc, I feel that the earlier design that I had posted of notification between LMB and EFI to have a synchronous view of each other's memory would be a better approach. That way, the EFI memory module can then implement things that it needs to, from the EFI spec point of view, and the LMB module can then just update the EFI module of the memory that it is using.

-sughosh

Best regards

Heinrich

...

          if (!addr)
                  return EFI_OUT_OF_RESOURCES;
          break;
  case EFI_ALLOCATE_MAX_ADDRESS:
          /* Max address */

•         addr = efi_find_free_memory(len, *memory);
  

•         addr = (u64)lmb_alloc_base_flags(len, EFI_PAGE_SIZE, *memory,
  

•                                          flags);
          if (!addr)
                  return EFI_OUT_OF_RESOURCES;
          break;
  case EFI_ALLOCATE_ADDRESS:
          if (*memory & EFI_PAGE_MASK)
                  return EFI_NOT_FOUND;
  

•         /* Exact address, reserve it. The addr is already in *memory. */
  

•         ret = efi_check_allocated(*memory, false);
  

•         if (ret != EFI_SUCCESS)
  

•                 return EFI_NOT_FOUND;
  

•         addr = *memory;
  

•         addr = (u64)lmb_alloc_addr_flags(*memory, len, flags);
  

•         if (!addr)
  

•                 return EFI_OUT_OF_RESOURCES;
          break;
  default:
          /* UEFI doesn't specify other allocation types */
          return EFI_INVALID_PARAMETER;
  }
  
  

• addr = (u64)(uintptr_t)map_sysmem(addr, 0);
  /* Reserve that map in our memory maps */
  ret = efi_add_memory_map_pg(addr, pages, memory_type, true);
  if (ret != EFI_SUCCESS)
  

@@ -555,6 +512,9 @@ efi_status_t efi_allocate_pages(enum efi_allocate_type type, */ efi_status_t efi_free_pages(uint64_t memory, efi_uintn_t pages) {

• u64 len;
  

• uint flags;
  

• long status;
  efi_status_t ret;
  
  ret = efi_check_allocated(memory, true);
  

@@ -568,6 +528,12 @@ efi_status_t efi_free_pages(uint64_t memory, efi_uintn_t pages) return EFI_INVALID_PARAMETER; }

• flags = LMB_NOOVERWRITE | LMB_NONOTIFY;
  

• len = (u64)pages << EFI_PAGE_SHIFT;
  

• status = lmb_free_flags(memory, len, flags);
  

• if (status)
  

•         return EFI_NOT_FOUND;
  

• ret = efi_add_memory_map_pg(memory, pages, EFI_CONVENTIONAL_MEMORY,
                              false);
  if (ret != EFI_SUCCESS)