diff options
| author | Ryan Grimm <grimm@linux.vnet.ibm.com> | 2019-08-19 23:13:21 -0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-08-30 09:55:41 +1000 |
| commit | 734560ac39aeb2516419c5878856df011f794a74 (patch) | |
| tree | e1a92b157035854c3787daf73e71e302bc60efda | |
| parent | 256ba2c1689efd4f5383cf7ebe2f9970c198b79d (diff) | |
| download | lwn-734560ac39aeb2516419c5878856df011f794a74.tar.gz lwn-734560ac39aeb2516419c5878856df011f794a74.zip | |
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: Ryan Grimm <grimm@linux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190820021326.6884-12-bauerman@linux.ibm.com
| -rw-r--r-- | Documentation/ABI/testing/sysfs-devices-system-cpu | 10 | ||||
| -rw-r--r-- | arch/powerpc/kernel/sysfs.c | 20 |
2 files changed, 30 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index 5f7d7b14fa44..06d0931119cc 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -562,3 +562,13 @@ Description: Umwait control or C0.2 state. The time is an unsigned 32-bit number. Note that a value of zero means there is no limit. 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. diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c index e2147d7c9e72..80a676da11cb 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 +716,23 @@ static struct device_attribute pa6t_attrs[] = { #endif /* HAS_PPC_PMC_PA6T */ #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) { struct cpu *c = &per_cpu(cpu_devices, cpu); @@ -1058,6 +1076,8 @@ static int __init topology_init(void) sysfs_create_dscr_default(); #endif /* CONFIG_PPC64 */ + create_svm_file(); + return 0; } subsys_initcall(topology_init); |