Re: [PATCH v5 5/5] x86/CPU/AMD: Print AGESA string from DMI additional information entry

[Borislav Petkov]

On Fri, Jan 23, 2026 at 03:30:56PM -0600, Mario Limonciello (AMD) wrote:
> From: Yazen Ghannam <yazen.ghannam@xxxxxxx>
> 
> Type 40 entries (Additional Information) are summarized in section 7.41
> as part of the SMBIOS specification.  Generally, these entries aren't
> interesting to save.
> 
> However on some AMD Zen systems, the AGESA version is stored here. This
> is useful to save to the kernel message logs for debugging. It can be
> used to cross-reference issues.
> 
> Implement an iterator for the Additional Information entries. Use this
> to find and print the AGESA string. Do so in AMD code, since the use
> case is AMD-specific.

Please do not explain the diff.

> Signed-off-by: Yazen Ghannam <yazen.ghannam@xxxxxxx>
> Co-developed-by: "Mario Limonciello (AMD)" <superm1@xxxxxxxxxx>
> Signed-off-by: "Mario Limonciello (AMD)" <superm1@xxxxxxxxxx>
> ---
> v5:
>  * Return "" in !CONFIG_DMI case (LKP robot, Yazen)
> v4:
>  * New patch (based upon older versions though)
> ---
>  arch/x86/kernel/cpu/amd.c   | 53 +++++++++++++++++++++++++++++++++++++
>  drivers/firmware/dmi_scan.c |  3 ++-
>  include/linux/dmi.h         | 18 +++++++++++++
>  3 files changed, 73 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index bc94ff1e250ad..aa04a27aeb107 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -1,6 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0-only
>  #include <linux/export.h>
>  #include <linux/bitops.h>
> +#include <linux/dmi.h>
>  #include <linux/elf.h>
>  #include <linux/mm.h>
>  #include <linux/kvm_types.h>
> @@ -1404,3 +1405,55 @@ static __init int print_s5_reset_status_mmio(void)
>  	return 0;
>  }
>  late_initcall(print_s5_reset_status_mmio);
> +
> +static void __init amd_dmi_scan_additional(const struct dmi_header *d, void *p)

It's a static - no need for the "amd_" prefix.

> +{
> +	struct dmi_a_info *info = (struct dmi_a_info *)d;
> +	void *next, *end;

This needs a 

	if (!IS_ENABLED(CONFIG_DMI))
		return;

> +
> +	/*
> +	 * DMI Additional Info table has a 'count' field. But it's not very
> +	 * helpful since the entries are variable length. So don't use it.
> +	 */
> +	if (info->header.type != DMI_ENTRY_ADDITIONAL ||
> +	    info->header.length < DMI_A_INFO_MIN_SIZE)
> +		return;
> +
> +	/*
> +	 * Get the first entry.
> +	 * The minimum table size guarantees at least one entry is present.
> +	 */
> +	next = (void *)(info + 1);
> +	end  = (void *)info + info->header.length;

This end needs to be corrected to some sane upper limit because we don't trust
firmware one bit.

> +
> +	do {
> +		struct dmi_a_info_entry *entry;
> +		const char *string_ptr;
> +
> +		entry = (struct dmi_a_info_entry *)next;
> +
> +		/*
> +		 * Not much can be done to validate data. At least the entry
> +		 * length shouldn't be 0.
> +		 */
> +		if (!entry->length)
> +			return;
> +
> +		string_ptr = dmi_string_nosave(&info->header, entry->str_num);
> +
> +		/* Only one AGESA string is expected. */

Superfluous comment.

> +		if (!strncmp(string_ptr, "AGESA", 5)) {
> +			pr_info("%s\n", string_ptr);

So on this Zen5 laptop here, this dumps:

[    0.840480] AGESA!V9 StrixPI-FP8 1.0.0.1d

I guess we can make that:

[    0.840480] AGESA: V9 StrixPI-FP8 1.0.0.1d

no?

Thx.

-- 
Regards/Gruss,
    Boris.

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