From: Ryan Grimm <gr...@linux.vnet.ibm.com>
User space might want to know it's running in a secure VM. It can't do
a mfmsr because mfmsr is a privileged instruction.
The solution here is to create a cpu attribute:
/sys/devices/system/cpu/svm
which will read 0 or 1 based on the S bit of the guest's CPU 0.
Signed-off-by: Ryan Grimm <gr...@linux.vnet.ibm.com>
Reviewed-by: Ram Pai <linux...@us.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauer...@linux.ibm.com>
---
arch/powerpc/kernel/sysfs.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index e2147d7c9e72..f7100ab77d29 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -19,6 +19,7 @@
#include <asm/smp.h>
#include <asm/pmc.h>
#include <asm/firmware.h>
+#include <asm/svm.h>
#include "cacheinfo.h"
#include "setup.h"
@@ -715,6 +716,32 @@ static struct device_attribute pa6t_attrs[] = {
#endif /* HAS_PPC_PMC_PA6T */
#endif /* HAS_PPC_PMC_CLASSIC */
+#ifdef CONFIG_PPC_SVM
+static void get_svm(void *val)
+{
+ u32 *value = val;
+
+ *value = is_secure_guest();
+}
+
+static ssize_t show_svm(struct device *dev, struct device_attribute *attr,
char *buf)
+{
+ u32 val;
+ smp_call_function_single(0, get_svm, &val, 1);
+ return sprintf(buf, "%u\n", val);
+}
+static DEVICE_ATTR(svm, 0444, show_svm, NULL);
+
+static void create_svm_file(void)
+{
+ device_create_file(cpu_subsys.dev_root, &dev_attr_svm);
+}
+#else
+static void create_svm_file(void)
+{
+}
+#endif /* CONFIG_PPC_SVM */
+
static int register_cpu_online(unsigned int cpu)
{
struct cpu *c = &per_cpu(cpu_devices, cpu);
@@ -1058,6 +1085,8 @@ static int __init topology_init(void)
sysfs_create_dscr_default();
#endif /* CONFIG_PPC64 */
+ create_svm_file();
+
return 0;
}
subsys_initcall(topology_init);
