[PATCH]: NMI: add Intel processor 0x6f4 to NMI perfctr1 workaround

[Prarit Bhargava <prarit@redhat.com>]

Expand Intel NMI perfctr1 workaround to include a Core2 processor stepping
(cpuid family-6, model-f, stepping-4). Resolves a situation where the NMI
would not enable on these processors.

Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Prarit Bhargava <prarit@redhat.com>

diff --git a/arch/x86/kernel/cpu/perfctr-watchdog.c b/arch/x86/kernel/cpu/perfctr-watchdog.c
index f6c70a1..4ad5199 100644
--- a/arch/x86/kernel/cpu/perfctr-watchdog.c
+++ b/arch/x86/kernel/cpu/perfctr-watchdog.c
@@ -716,11 +716,15 @@ static void probe_nmi_watchdog(void)
 		wd_ops = &k7_wd_ops;
 		break;
 	case X86_VENDOR_INTEL:
-		/*
-		 * Work around Core Duo (Yonah) errata AE49 where perfctr1
-		 * doesn't have a working enable bit.
+		/* Work around where perfctr1 doesn't have a working enable
+		 * bit as described in the following errata:
+		 * AE49 Core Duo and Intel Core Solo 65 nm
+		 * AN49 Intel Pentium Dual-Core
+		 * AF49 Dual-Core Intel Xeon Processor LV
 		 */
-		if (boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 14) {
+		if ((boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 14) ||
+		    ((boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 15 &&
+		     boot_cpu_data.x86_mask == 4))) {
 			intel_arch_wd_ops.perfctr = MSR_ARCH_PERFMON_PERFCTR0;
 			intel_arch_wd_ops.evntsel = MSR_ARCH_PERFMON_EVENTSEL0;
 		}