From: Miroslav Rezanina <mrezanin@redhat.com>
Date: Mon, 8 Jun 2009 03:22:06 -0400
Subject: [xen] x86: make NMI detection work
Message-id: 1425322985.100091244445726651.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com
O-Subject: Re: [PATCH RHEL5.5] BZ494120 - XEN NMI detection fails on Dell 1950 server
Bugzilla: 494120
RH-Acked-by: Chris Lalancette <clalance@redhat.com>
RH-Acked-by: Rik van Riel <riel@redhat.com>
RH-Acked-by: Don Dutile <ddutile@redhat.com>

Version 2 of patch. Due to copy paste tabs were replaced with spaces.

BZ #494120 (https://bugzilla.redhat.com/show_bug.cgi?id=494120)

Description:
------------
With watchdog option set on, boot test of NMI reports processors stucks, that mean NMI is not working properly.

Fix:
----
Checking differencies between RHEL and upstream source code, and upstream c/s,  I found c/s 18645. Applying this c/s cause watchdog test to pass successfuly.

Testing:
--------
Patched XEN hypervisor was used on x86_64 machine. xm dmesg output checked.

Patch:
------

diff --git a/arch/x86/nmi.c b/arch/x86/nmi.c
index 53d15a5..b30df07 100644
--- a/arch/x86/nmi.c
+++ b/arch/x86/nmi.c
@@ -73,7 +73,7 @@ int nmi_active;
 #define P6_EVNTSEL_OS		(1 << 17)
 #define P6_EVNTSEL_USR		(1 << 16)
 #define P6_EVENT_CPU_CLOCKS_NOT_HALTED	0x79
-#define P6_NMI_EVENT		P6_EVENT_CPU_CLOCKS_NOT_HALTED
+#define CORE_EVENT_CPU_CLOCKS_NOT_HALTED 0x3c
 
 #define P4_ESCR_EVENT_SELECT(N)	((N)<<25)
 #define P4_CCCR_OVF_PMI0	(1<<26)
@@ -248,7 +248,7 @@ static void __pminit setup_k7_watchdog(void)
     wrmsr(MSR_K7_EVNTSEL0, evntsel, 0);
 }
 
-static void __pminit setup_p6_watchdog(void)
+static void __pminit setup_p6_watchdog(unsigned counter)
 {
     unsigned int evntsel;
 
@@ -260,7 +260,7 @@ static void __pminit setup_p6_watchdog(void)
     evntsel = P6_EVNTSEL_INT
         | P6_EVNTSEL_OS
         | P6_EVNTSEL_USR
-        | P6_NMI_EVENT;
+        | counter;
 
     wrmsr(MSR_P6_EVNTSEL0, evntsel, 0);
     write_watchdog_counter("P6_PERFCTR0");
@@ -326,7 +326,9 @@ void __pminit setup_apic_nmi_watchdog(void)
     case X86_VENDOR_INTEL:
         switch (boot_cpu_data.x86) {
         case 6:
-            setup_p6_watchdog();
+            setup_p6_watchdog((boot_cpu_data.x86_model < 14) 
+                              ? P6_EVENT_CPU_CLOCKS_NOT_HALTED
+                              : CORE_EVENT_CPU_CLOCKS_NOT_HALTED);
             break;
         case 15:
             if (!setup_p4_watchdog())