From 82bc51acf7718d8e54a8d27a4b57f709ae9b7b0b Mon Sep 17 00:00:00 2001
From: art <art@openbsd.org>
Date: Wed, 13 Aug 2008 15:44:44 +0000
Subject: [PATCH] Disable the fantastics mis-feature on some newer Turion CPUs
 called C1E. This "power saving" disables the apic when both cpu cores hit the
 hlt instruction which kills our timer.

From FreeBSD.
---
 sys/arch/amd64/amd64/lapic.c        | 27 ++++++++++++++++++++++++++-
 sys/arch/amd64/include/specialreg.h |  6 +++++-
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/sys/arch/amd64/amd64/lapic.c b/sys/arch/amd64/amd64/lapic.c
index 603cd4d5025..df55dc09ef5 100644
--- a/sys/arch/amd64/amd64/lapic.c
+++ b/sys/arch/amd64/amd64/lapic.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: lapic.c,v 1.14 2008/06/26 05:42:09 ray Exp $	*/
+/*	$OpenBSD: lapic.c,v 1.15 2008/08/13 15:44:44 art Exp $	*/
 /* $NetBSD: lapic.c,v 1.2 2003/05/08 01:04:35 fvdl Exp $ */
 
 /*-
@@ -157,6 +157,31 @@ lapic_set_lvt(void)
 	}
 #endif
 
+	if (strcmp(cpu_vendor, "AuthenticAMD") == 0) {
+		/*
+		 * Detect the presence of C1E capability mostly on latest
+		 * dual-cores (or future) k8 family. This mis-feature renders
+		 * the local APIC timer dead, so we disable it by reading
+		 * the Interrupt Pending Message register and clearing both
+		 * C1eOnCmpHalt (bit 28) and SmiOnCmpHalt (bit 27).
+		 * 
+		 * Reference:
+		 *   "BIOS and Kernel Developer's Guide for AMD NPT
+		 *    Family 0Fh Processors"
+		 *   #32559 revision 3.00
+		 */
+		if ((cpu_id & 0x00000f00) == 0x00000f00 &&
+		    (cpu_id & 0x0fff0000) >= 0x00040000) {
+			uint64_t msr;
+
+			msr = rdmsr(MSR_INT_PEN_MSG);
+			if (msr & (IPM_C1E_CMP_HLT|IPM_SMI_CMP_HLT)) {
+				msr &= ~(IPM_C1E_CMP_HLT|IPM_SMI_CMP_HLT);
+				wrmsr(MSR_INT_PEN_MSG, msr);
+			}
+		}
+	}
+
 	for (i = 0; i < mp_nintrs; i++) {
 		mpi = &mp_intrs[i];
 		if (mpi->ioapic == NULL && (mpi->cpu_id == MPS_ALL_APICS
diff --git a/sys/arch/amd64/include/specialreg.h b/sys/arch/amd64/include/specialreg.h
index 0fc1094e793..f8d7448843e 100644
--- a/sys/arch/amd64/include/specialreg.h
+++ b/sys/arch/amd64/include/specialreg.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: specialreg.h,v 1.12 2008/06/13 00:00:45 jsg Exp $	*/
+/*	$OpenBSD: specialreg.h,v 1.13 2008/08/13 15:44:44 art Exp $	*/
 /*	$NetBSD: specialreg.h,v 1.1 2003/04/26 18:39:48 fvdl Exp $	*/
 /*	$NetBSD: x86/specialreg.h,v 1.2 2003/04/25 21:54:30 fvdl Exp $	*/
 
@@ -289,6 +289,10 @@
 #define MSR_FSBASE	0xc0000100		/* 64bit offset for fs: */
 #define MSR_GSBASE	0xc0000101		/* 64bit offset for gs: */
 #define MSR_KERNELGSBASE 0xc0000102		/* storage for swapgs ins */
+#define MSR_INT_PEN_MSG	0xc0010055		/* Interrupt pending message */
+
+#define IPM_C1E_CMP_HLT	0x10000000
+#define IPM_SMI_CMP_HLT	0x08000000
 
 /*
  * These require a 'passcode' for access.  See cpufunc.h.
-- 
2.20.1