x86/ucode: Exclude Zen6 from entrysign digest checking

There is a 3rd path which should have gained an is_zen6_uarch() check to
exclude Zen6 from entrysign mitigations.

Fixes: bd15fdedaf ("x86/ucode: Exclude Zen6 from entrysign mitigations")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Teddy Astie <teddy.astie@vates.tech>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: 6ba5e9c7b8
master date: 2026-06-16 18:33:39 +0100

xen/arch/x86/cpu/microcode/amd.c

@@ -129,7 +129,8 @@ static bool check_digest(const struct container_microcode *mc)
      * the digest of the patch against a list of known provenance.
      */
     if ( boot_cpu_data.x86 < 0x17 || boot_cpu_data.x86 > 0x1a ||
-         entrysign_mitigiated_in_firmware || !opt_digest_check )
+         is_zen6_uarch() || entrysign_mitigiated_in_firmware ||
+         !opt_digest_check )
         return true;
 
     pd = bsearch(&patch->patch_id, patch_digests, ARRAY_SIZE(patch_digests),