x86: handle PAT more like other CPU features

Impact: Cleanup

When PAT was originally introduced, it was handled specially for a few
reasons:

- PAT bugs are hard to track down, so we wanted to maintain a
  whitelist of CPUs.
- The i386 and x86-64 CPUID code was not yet unified.

Both of these are now obsolete, so handle PAT like any other features,
including ordinary feature blacklisting due to known bugs.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/kernel/cpu/addon_cpuid_features.c

@@ -143,37 +143,3 @@ void __cpuinit detect_extended_topology(struct cpuinfo_x86 *c)
 	return;
 #endif
 }
-
-#ifdef CONFIG_X86_PAT
-void __cpuinit validate_pat_support(struct cpuinfo_x86 *c)
-{
-	if (!cpu_has_pat)
-		pat_disable("PAT not supported by CPU.");
-
-	switch (c->x86_vendor) {
-	case X86_VENDOR_INTEL:
-		/*
-		 * There is a known erratum on Pentium III and Core Solo
-		 * and Core Duo CPUs.
-		 * " Page with PAT set to WC while associated MTRR is UC
-		 *   may consolidate to UC "
-		 * Because of this erratum, it is better to stick with
-		 * setting WC in MTRR rather than using PAT on these CPUs.
-		 *
-		 * Enable PAT WC only on P4, Core 2 or later CPUs.
-		 */
-		if (c->x86 > 0x6 || (c->x86 == 6 && c->x86_model >= 15))
-			return;
-
-		pat_disable("PAT WC disabled due to known CPU erratum.");
-		return;
-
-	case X86_VENDOR_AMD:
-	case X86_VENDOR_CENTAUR:
-	case X86_VENDOR_TRANSMETA:
-		return;
-	}
-
-	pat_disable("PAT disabled. Not yet verified on this CPU type.");
-}
-#endif