linux-kernel - [PATCH 4/7] paravirtualization: Allow selected bug checks to be skipped by paravirt kernels

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Message-Id: <1162377043.23462.12.camel@localhost.localdomain>
Date:	Wed, 01 Nov 2006 21:30:43 +1100
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Andi Kleen <ak@....de>
Cc:	Andi Kleen <ak@...e.de>, virtualization@...ts.osdl.org,
	Chris Wright <chrisw@...s-sol.org>, akpm@...l.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/7] paravirtualization: Allow selected bug checks to be
	skipped by paravirt kernels

Allow selected bug checks to be skipped by paravirt kernels.  The two most
important are the F00F workaround (which is either done by the hypervisor,
or not required), and the 'hlt' instruction check, which can break under
some hypervisors.

Signed-off-by: Zachary Amsden <zach@...are.com>
Signed-off-by: Chris Wright <chrisw@...s-sol.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@...p.org>

===================================================================
--- a/arch/i386/kernel/cpu/intel.c
+++ b/arch/i386/kernel/cpu/intel.c
@@ -107,7 +107,7 @@ static void __cpuinit init_intel(struct 
 	 * Note that the workaround only should be initialized once...
 	 */
 	c->f00f_bug = 0;
-	if ( c->x86 == 5 ) {
+	if (!paravirt_enabled() && c->x86 == 5) {
 		static int f00f_workaround_enabled = 0;
 
 		c->f00f_bug = 1;
===================================================================
--- a/include/asm-i386/bugs.h
+++ b/include/asm-i386/bugs.h
@@ -21,6 +21,7 @@
 #include <asm/processor.h>
 #include <asm/i387.h>
 #include <asm/msr.h>
+#include <asm/paravirt.h>
 
 static int __init no_halt(char *s)
 {
@@ -91,6 +92,9 @@ static void __init check_fpu(void)
 
 static void __init check_hlt(void)
 {
+	if (paravirt_enabled())
+		return;
+
 	printk(KERN_INFO "Checking 'hlt' instruction... ");
 	if (!boot_cpu_data.hlt_works_ok) {
 		printk("disabled\n");


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