[PATCH 3/3] sysctl: introduce a new interface to control kdump-vmcs-clear behaviour

[Zhang Yanfei <zhangyanfei@cn.fujitsu.com>]

This patch exports the variable clear_loaded_vmcs_enabled to userspace.

Signed-off-by: zhangyanfei <zhangyanfei@cn.fujitsu.com>
---
 Documentation/sysctl/kernel.txt |    8 ++++++++
 kernel/sysctl.c                 |   10 ++++++++++
 2 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 6d78841..038148b 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -25,6 +25,7 @@ show up in /proc/sys/kernel:
 - bootloader_version	     [ X86 only ]
 - callhome		     [ S390 only ]
 - cap_last_cap
+- clear_loaded_vmcs	     [ X86 only ]
 - core_pattern
 - core_pipe_limit
 - core_uses_pid
@@ -164,6 +165,13 @@ CAP_LAST_CAP from the kernel.
 
 ==============================================================
 
+clear_loaded_vmcs
+
+Controls if VMCSs should be cleared when host is doing kdump.  Exports
+clear_loaded_vmcs_enabled from the kernel.
+
+==============================================================
+
 core_pattern:
 
 core_pattern is used to specify a core dumpfile pattern name.
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 4ab1187..3ab7d9c 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -63,6 +63,7 @@
 
 #include <asm/uaccess.h>
 #include <asm/processor.h>
+#include <asm/kexec.h>
 
 #ifdef CONFIG_X86
 #include <asm/nmi.h>
@@ -994,6 +995,15 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
+#ifdef CONFIG_KEXEC
+	{
+		.procname	= "clear_loaded_vmcs",
+		.data		= &clear_loaded_vmcs_enabled,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+#endif
 	{ }
 };
 
-- 
1.7.1