x86/cpu/intel: Replace Family 15 checks with VFM ones

Introduce names for some old pentium 4 models and replace the x86_model
checks with VFM ones.

Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20250219184133.816753-7-sohil.mehta@intel.com

Author: sohilmeh

arch/x86/include/asm/intel-family.h

@@ -184,6 +184,10 @@
 /* Family 5 */
 #define INTEL_QUARK_X1000		IFM(5, 0x09) /* Quark X1000 SoC */
 
+/* Family 15 - NetBurst */
+#define INTEL_P4_WILLAMETTE		IFM(15, 0x01) /* Also Xeon Foster */
+#define INTEL_P4_PRESCOTT		IFM(15, 0x03)
+
 /* Family 19 */
 #define INTEL_PANTHERCOVE_X		IFM(19, 0x01) /* Diamond Rapids */
 

arch/x86/kernel/cpu/intel.c

@@ -247,8 +247,8 @@ static void early_init_intel(struct cpuinfo_x86 *c)
 #endif
 
 	/* CPUID workaround for 0F33/0F34 CPU */
-	if (c->x86 == 0xF && c->x86_model == 0x3
-	    && (c->x86_stepping == 0x3 || c->x86_stepping == 0x4))
+	if (c->x86_vfm == INTEL_P4_PRESCOTT &&
+	    (c->x86_stepping == 0x3 || c->x86_stepping == 0x4))
 		c->x86_phys_bits = 36;
 
 	/*
@@ -421,7 +421,7 @@ static void intel_workarounds(struct cpuinfo_x86 *c)
 	 * P4 Xeon erratum 037 workaround.
 	 * Hardware prefetcher may cause stale data to be loaded into the cache.
 	 */
-	if ((c->x86 == 15) && (c->x86_model == 1) && (c->x86_stepping == 1)) {
+	if (c->x86_vfm == INTEL_P4_WILLAMETTE && c->x86_stepping == 1) {
 		if (msr_set_bit(MSR_IA32_MISC_ENABLE,
 				MSR_IA32_MISC_ENABLE_PREFETCH_DISABLE_BIT) > 0) {
 			pr_info("CPU: C0 stepping P4 Xeon detected.\n");