Commit 734560ac authored by Ryan Grimm's avatar Ryan Grimm Committed by Michael Ellerman

powerpc/pseries/svm: Export guest SVM status to user space via sysfs

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 current CPU.
Signed-off-by: default avatarRyan Grimm <grimm@linux.vnet.ibm.com>
Signed-off-by: default avatarThiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190820021326.6884-12-bauerman@linux.ibm.com
parent 256ba2c1
...@@ -562,3 +562,13 @@ Description: Umwait control ...@@ -562,3 +562,13 @@ Description: Umwait control
or C0.2 state. The time is an unsigned 32-bit number. or C0.2 state. The time is an unsigned 32-bit number.
Note that a value of zero means there is no limit. Note that a value of zero means there is no limit.
Low order two bits must be zero. Low order two bits must be zero.
What: /sys/devices/system/cpu/svm
Date: August 2019
Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
Description: Secure Virtual Machine
If 1, it means the system is using the Protected Execution
Facility in POWER9 and newer processors. i.e., it is a Secure
Virtual Machine.
...@@ -19,6 +19,7 @@ ...@@ -19,6 +19,7 @@
#include <asm/smp.h> #include <asm/smp.h>
#include <asm/pmc.h> #include <asm/pmc.h>
#include <asm/firmware.h> #include <asm/firmware.h>
#include <asm/svm.h>
#include "cacheinfo.h" #include "cacheinfo.h"
#include "setup.h" #include "setup.h"
...@@ -715,6 +716,23 @@ static struct device_attribute pa6t_attrs[] = { ...@@ -715,6 +716,23 @@ static struct device_attribute pa6t_attrs[] = {
#endif /* HAS_PPC_PMC_PA6T */ #endif /* HAS_PPC_PMC_PA6T */
#endif /* HAS_PPC_PMC_CLASSIC */ #endif /* HAS_PPC_PMC_CLASSIC */
#ifdef CONFIG_PPC_SVM
static ssize_t show_svm(struct device *dev, struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%u\n", is_secure_guest());
}
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) static int register_cpu_online(unsigned int cpu)
{ {
struct cpu *c = &per_cpu(cpu_devices, cpu); struct cpu *c = &per_cpu(cpu_devices, cpu);
...@@ -1058,6 +1076,8 @@ static int __init topology_init(void) ...@@ -1058,6 +1076,8 @@ static int __init topology_init(void)
sysfs_create_dscr_default(); sysfs_create_dscr_default();
#endif /* CONFIG_PPC64 */ #endif /* CONFIG_PPC64 */
create_svm_file();
return 0; return 0;
} }
subsys_initcall(topology_init); subsys_initcall(topology_init);
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment