[PATCH v4 4/7] smbios: Use SMBIOS 3.0 to support an address above 4GB

[Ilias Apalodimas]

Hi Simon,

On Wed, 27 Dec 2023 at 09:40, Simon Glass <sjg at chromium.org> wrote:
>
> When the SMBIOS table is written to an address above 4GB a 32-bit table
> address is not large enough.
>
> Use an SMBIOS3 table in that case.

Maybe I missed this on the previous revisions, but is there a reason
we don't always use SMBIOS3 now? And perhaps try to install SMBIOS2 if
1. we fail
2. and the address is < 4GB

Thanks
/Ilias
>
> Note that we cannot use efi_allocate_pages() since this function has
> nothing to do with EFI. There is no equivalent function to allocate
> memory below 4GB in U-Boot. One solution would be to create a separate
> malloc() pool, or just always put the malloc() pool below 4GB.
>
> - Use log_debug() for warning
> - Rebase on Heinrich's smbios.h patch
> - Set the checksum for SMBIOS3
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> Changes in v4:
> - Check the start of the table rather than the end
>
> Changes in v2:
> - Check the end of the table rather than the start.
>
>  include/smbios.h |  6 +++++-
>  lib/smbios.c     | 30 +++++++++++++++++++++++++-----
>  2 files changed, 30 insertions(+), 6 deletions(-)
>
> diff --git a/include/smbios.h b/include/smbios.h
> index e601283d293..77be58887a2 100644
> --- a/include/smbios.h
> +++ b/include/smbios.h
> @@ -12,7 +12,7 @@
>
>  /* SMBIOS spec version implemented */
>  #define SMBIOS_MAJOR_VER       3
> -#define SMBIOS_MINOR_VER       0
> +#define SMBIOS_MINOR_VER       7
>
>  enum {
>         SMBIOS_STR_MAX  = 64,   /* Maximum length allowed for a string */
> @@ -80,6 +80,10 @@ struct __packed smbios3_entry {
>         u64 struct_table_address;
>  };
>
> +/* These two structures should use the same amount of 16-byte-aligned space */
> +static_assert(ALIGN(16, sizeof(struct smbios_entry)) ==
> +             ALIGN(16, sizeof(struct smbios3_entry)));
> +
>  /* BIOS characteristics */
>  #define BIOS_CHARACTERISTICS_PCI_SUPPORTED     (1 << 7)
>  #define BIOS_CHARACTERISTICS_UPGRADEABLE       (1 << 11)
> diff --git a/lib/smbios.c b/lib/smbios.c
> index eea72670bd9..7f79d969c92 100644
> --- a/lib/smbios.c
> +++ b/lib/smbios.c
> @@ -567,7 +567,11 @@ ulong write_smbios_table(ulong addr)
>         addr = ALIGN(addr, 16);
>         start_addr = addr;
>
> -       addr += sizeof(struct smbios_entry);
> +       /*
> +        * So far we don't know which struct will be used, but they both end
> +        * up using the same amount of 16-bit-aligned space
> +        */
> +       addr += max(sizeof(struct smbios_entry), sizeof(struct smbios3_entry));
>         addr = ALIGN(addr, 16);
>         tables = addr;
>
> @@ -590,16 +594,32 @@ ulong write_smbios_table(ulong addr)
>          * We must use a pointer here so things work correctly on sandbox. The
>          * user of this table is not aware of the mapping of addresses to
>          * sandbox's DRAM buffer.
> +        *
> +        * Check the address of the end of the tables. If it is above 4GB then
> +        * it is sensible to use SMBIOS3 even if the start of the table is below
> +        * 4GB (this case is very unlikely to happen in practice)
>          */
>         table_addr = (ulong)map_sysmem(tables, 0);
> -       if (sizeof(table_addr) > sizeof(u32) && table_addr > (ulong)UINT_MAX) {
> +       if (sizeof(table_addr) > sizeof(u32) && addr >= (ulong)UINT_MAX) {
> +               struct smbios3_entry *se;
>                 /*
>                  * We need to put this >32-bit pointer into the table but the
>                  * field is only 32 bits wide.
>                  */
> -               printf("WARNING: SMBIOS table_address overflow %llx\n",
> -                      (unsigned long long)table_addr);
> -               addr = 0;
> +               log_debug("WARNING: Using SMBIOS3.0 due to table-address overflow %lx\n",
> +                         table_addr);
> +               se = map_sysmem(start_addr, sizeof(struct smbios_entry));
> +               memset(se, '\0', sizeof(struct smbios_entry));
> +               memcpy(se->anchor, "_SM3_", 5);
> +               se->length = sizeof(struct smbios3_entry);
> +               se->major_ver = SMBIOS_MAJOR_VER;
> +               se->minor_ver = SMBIOS_MINOR_VER;
> +               se->doc_rev = 0;
> +               se->entry_point_rev = 1;
> +               se->max_struct_size = len;
> +               se->struct_table_address = table_addr;
> +               se->checksum = table_compute_checksum(se,
> +                                               sizeof(struct smbios3_entry));
>         } else {
>                 struct smbios_entry *se;
>
> --
> 2.34.1
>