[PATCH] i386: PARAVIRT: Allow boot-time disable of paravirt_ops patching

Add "noreplace-paravirt" to disable paravirt_ops patching.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 16 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 242b3a09b6ce..38d7db3262c7 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -64,6 +64,7 @@ parameter is applicable:
         GENERIC_TIME The generic timeofday code is enabled.
         NFS     Appropriate NFS support is enabled.
         OSS     OSS sound support is enabled.
+        PV_OPS  A paravirtualized kernel
         PARIDE  The ParIDE subsystem is enabled.
         PARISC  The PA-RISC architecture is enabled.
         PCI     PCI bus support is enabled.
@@ -1164,6 +1165,8 @@ and is between 256 and 4096 characters. It is defined in the file
 
         nomce           [IA-32] Machine Check Exception
 
+        noreplace-paravirt      [IA-32,PV_OPS] Don't patch paravirt_ops
+
         noreplace-smp   [IA-32,SMP] Don't replace SMP instructions
                         with UP alternatives
 
diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index c5d037c60950..080a59d56ea6 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -30,6 +30,16 @@ static int __init setup_noreplace_smp(char *str)
 }
 __setup("noreplace-smp", setup_noreplace_smp);
 
+#ifdef CONFIG_PARAVIRT
+static int noreplace_paravirt = 0;
+
+static int __init setup_noreplace_paravirt(char *str)
+{
+        noreplace_paravirt = 1;
+        return 1;
+}
+__setup("noreplace-paravirt", setup_noreplace_paravirt);
+#endif
 
 #define DPRINTK(fmt, args...) if (debug_alternative) \
         printk(KERN_DEBUG fmt, args)
@@ -330,6 +340,9 @@ void apply_paravirt(struct paravirt_patch_site *start,
 {
         struct paravirt_patch_site *p;
 
+        if (noreplace_paravirt)
+                return;
+
         for (p = start; p < end; p++) {
                 unsigned int used;