x86/CPU/AMD: Add X86_FEATURE_ZEN6

Add a synthetic feature flag for Zen6.

  [  bp: Move the feature flag to a free slot and avoid future merge
     conflicts from incoming stuff. ]

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250513204857.3376577-1-yazen.ghannam@amd.com

Author: yghannam

arch/x86/include/asm/cpufeatures.h

@@ -75,7 +75,7 @@
 #define X86_FEATURE_CENTAUR_MCR		( 3*32+ 3) /* "centaur_mcr" Centaur MCRs (= MTRRs) */
 #define X86_FEATURE_K8			( 3*32+ 4) /* Opteron, Athlon64 */
 #define X86_FEATURE_ZEN5		( 3*32+ 5) /* CPU based on Zen5 microarchitecture */
-/* Free                                 ( 3*32+ 6) */
+#define X86_FEATURE_ZEN6		( 3*32+ 6) /* CPU based on Zen6 microarchitecture */
 /* Free                                 ( 3*32+ 7) */
 #define X86_FEATURE_CONSTANT_TSC	( 3*32+ 8) /* "constant_tsc" TSC ticks at a constant rate */
 #define X86_FEATURE_UP			( 3*32+ 9) /* "up" SMP kernel running on UP */

arch/x86/kernel/cpu/amd.c

@@ -472,6 +472,11 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 		case 0x60 ... 0x7f:
 			setup_force_cpu_cap(X86_FEATURE_ZEN5);
 			break;
+		case 0x50 ... 0x5f:
+		case 0x90 ... 0xaf:
+		case 0xc0 ... 0xcf:
+			setup_force_cpu_cap(X86_FEATURE_ZEN6);
+			break;
 		default:
 			goto warn;
 		}