[PATCH v1 0/4] x86: Remove direct use of MSR_IA32_ENERGY_PERF_BIAS

[PATCH v1 0/4] x86: Remove direct use of MSR_IA32_ENERGY_PERF_BIAS

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

Hi,

here's v2 with some of Shuah's comments integrated.

If no one has anything against it, I'll route them all through tip.

Thx.

---
Changelog:

v0:
--

here's something from my todo list: remove all in-kernel tools use of
that MSR and lastly drop it from the allowed-MSRs-list in the filtering.

Out-of-tree tools should do a similar, trivial conversion.

Constructive comments are, as always, appreciated.

Borislav Petkov (4):
  tools/power/cpupower: Read energy_perf_bias from sysfs
  tools/power/turbostat: Read energy_perf_bias from sysfs
  tools/power/x86_energy_perf_policy: Read energy_perf_bias from sysfs
  x86/msr: Do not allow writes to MSR_IA32_ENERGY_PERF_BIAS

 arch/x86/kernel/msr.c                         |   3 -
 tools/power/cpupower/lib/cpupower.c           |  23 +++-
 tools/power/cpupower/lib/cpupower_intern.h    |   5 +
 tools/power/cpupower/utils/cpupower-info.c    |   2 +-
 tools/power/cpupower/utils/cpupower-set.c     |   2 +-
 tools/power/cpupower/utils/helpers/helpers.h  |   8 +-
 tools/power/cpupower/utils/helpers/misc.c     |  48 ++++++++
 tools/power/cpupower/utils/helpers/msr.c      |  28 -----
 tools/power/x86/turbostat/turbostat.c         |  29 ++++-
 .../x86_energy_perf_policy.c                  | 109 ++++++++++++++++--
 10 files changed, 204 insertions(+), 53 deletions(-)

-- 
2.21.0

[PATCH v1 1/4] tools/power/cpupower: Read energy_perf_bias from sysfs

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

... instead of poking at the MSR. For that, move the accessor functions
to misc.c and add a sysfs-writing function too.

There should be no functional changes resulting from this.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Thomas Renninger <trenn@suse.com>
Cc: Shuah Khan <shuah@kernel.org>
---
 tools/power/cpupower/lib/cpupower.c          | 23 +++++++++-
 tools/power/cpupower/lib/cpupower_intern.h   |  5 ++
 tools/power/cpupower/utils/cpupower-info.c   |  2 +-
 tools/power/cpupower/utils/cpupower-set.c    |  2 +-
 tools/power/cpupower/utils/helpers/helpers.h |  8 ++--
 tools/power/cpupower/utils/helpers/misc.c    | 48 ++++++++++++++++++++
 tools/power/cpupower/utils/helpers/msr.c     | 28 ------------
 7 files changed, 81 insertions(+), 35 deletions(-)

diff --git a/tools/power/cpupower/lib/cpupower.c b/tools/power/cpupower/lib/cpupower.c
index 3656e697537e..3f7d0c0c5067 100644
--- a/tools/power/cpupower/lib/cpupower.c
+++ b/tools/power/cpupower/lib/cpupower.c
@@ -16,8 +16,8 @@
 
 unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
 {
-	int fd;
 	ssize_t numread;
+	int fd;
 
 	fd = open(path, O_RDONLY);
 	if (fd == -1)
@@ -35,6 +35,27 @@ unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
 	return (unsigned int) numread;
 }
 
+unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen)
+{
+	ssize_t numwritten;
+	int fd;
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1)
+		return 0;
+
+	numwritten = write(fd, buf, buflen - 1);
+	if (numwritten < 1) {
+		perror(path);
+		close(fd);
+		return -1;
+	}
+
+	close(fd);
+
+	return (unsigned int) numwritten;
+}
+
 /*
  * Detect whether a CPU is online
  *
diff --git a/tools/power/cpupower/lib/cpupower_intern.h b/tools/power/cpupower/lib/cpupower_intern.h
index 4887c76d23f8..ac1112b956ec 100644
--- a/tools/power/cpupower/lib/cpupower_intern.h
+++ b/tools/power/cpupower/lib/cpupower_intern.h
@@ -1,6 +1,11 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #define PATH_TO_CPU "/sys/devices/system/cpu/"
+
+#ifndef MAX_LINE_LEN
 #define MAX_LINE_LEN 4096
+#endif
+
 #define SYSFS_PATH_MAX 255
 
 unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen);
+unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen);
diff --git a/tools/power/cpupower/utils/cpupower-info.c b/tools/power/cpupower/utils/cpupower-info.c
index 0ba61a2c4d81..06345b543786 100644
--- a/tools/power/cpupower/utils/cpupower-info.c
+++ b/tools/power/cpupower/utils/cpupower-info.c
@@ -101,7 +101,7 @@ int cmd_info(int argc, char **argv)
 		}
 
 		if (params.perf_bias) {
-			ret = msr_intel_get_perf_bias(cpu);
+			ret = cpupower_intel_get_perf_bias(cpu);
 			if (ret < 0) {
 				fprintf(stderr,
 			_("Could not read perf-bias value[%d]\n"), ret);
diff --git a/tools/power/cpupower/utils/cpupower-set.c b/tools/power/cpupower/utils/cpupower-set.c
index 052044d7e012..180d5ba877e6 100644
--- a/tools/power/cpupower/utils/cpupower-set.c
+++ b/tools/power/cpupower/utils/cpupower-set.c
@@ -95,7 +95,7 @@ int cmd_set(int argc, char **argv)
 		}
 
 		if (params.perf_bias) {
-			ret = msr_intel_set_perf_bias(cpu, perf_bias);
+			ret = cpupower_intel_set_perf_bias(cpu, perf_bias);
 			if (ret) {
 				fprintf(stderr, _("Error setting perf-bias "
 						  "value on CPU %d\n"), cpu);
diff --git a/tools/power/cpupower/utils/helpers/helpers.h b/tools/power/cpupower/utils/helpers/helpers.h
index c258eeccd05f..37dac161f3fe 100644
--- a/tools/power/cpupower/utils/helpers/helpers.h
+++ b/tools/power/cpupower/utils/helpers/helpers.h
@@ -105,8 +105,8 @@ extern struct cpupower_cpu_info cpupower_cpu_info;
 extern int read_msr(int cpu, unsigned int idx, unsigned long long *val);
 extern int write_msr(int cpu, unsigned int idx, unsigned long long val);
 
-extern int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val);
-extern int msr_intel_get_perf_bias(unsigned int cpu);
+extern int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val);
+extern int cpupower_intel_get_perf_bias(unsigned int cpu);
 extern unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu);
 
 /* Read/Write msr ****************************/
@@ -150,9 +150,9 @@ static inline int read_msr(int cpu, unsigned int idx, unsigned long long *val)
 { return -1; };
 static inline int write_msr(int cpu, unsigned int idx, unsigned long long val)
 { return -1; };
-static inline int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val)
+static inline int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val)
 { return -1; };
-static inline int msr_intel_get_perf_bias(unsigned int cpu)
+static inline int cpupower_intel_get_perf_bias(unsigned int cpu)
 { return -1; };
 static inline unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
 { return 0; };
diff --git a/tools/power/cpupower/utils/helpers/misc.c b/tools/power/cpupower/utils/helpers/misc.c
index f406adc40bad..e8f8f643a627 100644
--- a/tools/power/cpupower/utils/helpers/misc.c
+++ b/tools/power/cpupower/utils/helpers/misc.c
@@ -1,7 +1,15 @@
 // SPDX-License-Identifier: GPL-2.0
+
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+
 #if defined(__i386__) || defined(__x86_64__)
 
 #include "helpers/helpers.h"
+#include "helpers/sysfs.h"
+
+#include "cpupower_intern.h"
 
 #define MSR_AMD_HWCR	0xc0010015
 
@@ -40,4 +48,44 @@ int cpufreq_has_boost_support(unsigned int cpu, int *support, int *active,
 		*support = *active = 1;
 	return 0;
 }
+
+int cpupower_intel_get_perf_bias(unsigned int cpu)
+{
+	char linebuf[MAX_LINE_LEN];
+	char path[SYSFS_PATH_MAX];
+	unsigned long val;
+	char *endp;
+
+	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
+		return -1;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu);
+
+	if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
+		return -1;
+
+	val = strtol(linebuf, &endp, 0);
+	if (endp == linebuf || errno == ERANGE)
+		return -1;
+
+	return val;
+}
+
+int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val)
+{
+	char path[SYSFS_PATH_MAX];
+	char linebuf[3] = {};
+
+	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
+		return -1;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu);
+	snprintf(linebuf, sizeof(linebuf), "%d", val);
+
+	if (cpupower_write_sysfs(path, linebuf, 3) <= 0)
+		return -1;
+
+	return 0;
+}
+
 #endif /* #if defined(__i386__) || defined(__x86_64__) */
diff --git a/tools/power/cpupower/utils/helpers/msr.c b/tools/power/cpupower/utils/helpers/msr.c
index ab9950748838..8b0b6be74bb8 100644
--- a/tools/power/cpupower/utils/helpers/msr.c
+++ b/tools/power/cpupower/utils/helpers/msr.c
@@ -11,7 +11,6 @@
 /* Intel specific MSRs */
 #define MSR_IA32_PERF_STATUS		0x198
 #define MSR_IA32_MISC_ENABLES		0x1a0
-#define MSR_IA32_ENERGY_PERF_BIAS	0x1b0
 #define MSR_NEHALEM_TURBO_RATIO_LIMIT	0x1ad
 
 /*
@@ -73,33 +72,6 @@ int write_msr(int cpu, unsigned int idx, unsigned long long val)
 	return -1;
 }
 
-int msr_intel_get_perf_bias(unsigned int cpu)
-{
-	unsigned long long val;
-	int ret;
-
-	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
-		return -1;
-
-	ret = read_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &val);
-	if (ret)
-		return ret;
-	return val;
-}
-
-int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val)
-{
-	int ret;
-
-	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
-		return -1;
-
-	ret = write_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, val);
-	if (ret)
-		return ret;
-	return 0;
-}
-
 unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
 {
 	unsigned long long val;
-- 
2.21.0

Re: [PATCH v1 1/4] tools/power/cpupower: Read energy_perf_bias from sysfs

[Shuah Khan]

On 10/29/20 1:02 PM, Borislav Petkov wrote:
> From: Borislav Petkov <bp@suse.de>
> 
> ... instead of poking at the MSR. For that, move the accessor functions
> to misc.c and add a sysfs-writing function too.
> 
> There should be no functional changes resulting from this.
> 
> Signed-off-by: Borislav Petkov <bp@suse.de>
> Cc: Thomas Renninger <trenn@suse.com>
> Cc: Shuah Khan <shuah@kernel.org>
> ---
>   tools/power/cpupower/lib/cpupower.c          | 23 +++++++++-
>   tools/power/cpupower/lib/cpupower_intern.h   |  5 ++
>   tools/power/cpupower/utils/cpupower-info.c   |  2 +-
>   tools/power/cpupower/utils/cpupower-set.c    |  2 +-
>   tools/power/cpupower/utils/helpers/helpers.h |  8 ++--
>   tools/power/cpupower/utils/helpers/misc.c    | 48 ++++++++++++++++++++
>   tools/power/cpupower/utils/helpers/msr.c     | 28 ------------
>   7 files changed, 81 insertions(+), 35 deletions(-)
> 

Thanks. Looks good to me.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah

[PATCH v1 2/4] tools/power/turbostat: Read energy_perf_bias from sysfs

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

... instead of poking at the MSR directly.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-pm@vger.kernel.org
---
 tools/power/x86/turbostat/turbostat.c | 29 ++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 33b370865d16..0baec7ea1bbd 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -1721,6 +1721,25 @@ int get_mp(int cpu, struct msr_counter *mp, unsigned long long *counterp)
 	return 0;
 }
 
+int get_epb(int cpu)
+{
+	char path[128 + PATH_BYTES];
+	int ret, epb = -1;
+	FILE *fp;
+
+	sprintf(path, "/sys/devices/system/cpu/cpu%d/power/energy_perf_bias", cpu);
+
+	fp = fopen_or_die(path, "r");
+
+	ret = fscanf(fp, "%d", &epb);
+	if (ret != 1)
+		err(1, "%s(%s)", __func__, path);
+
+	fclose(fp);
+
+	return epb;
+}
+
 void get_apic_id(struct thread_data *t)
 {
 	unsigned int eax, ebx, ecx, edx;
@@ -3631,9 +3650,8 @@ dump_sysfs_pstate_config(void)
  */
 int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 {
-	unsigned long long msr;
 	char *epb_string;
-	int cpu;
+	int cpu, epb;
 
 	if (!has_epb)
 		return 0;
@@ -3649,10 +3667,11 @@ int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 		return -1;
 	}
 
-	if (get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr))
+	epb = get_epb(cpu);
+	if (epb < 0)
 		return 0;
 
-	switch (msr & 0xF) {
+	switch (epb) {
 	case ENERGY_PERF_BIAS_PERFORMANCE:
 		epb_string = "performance";
 		break;
@@ -3666,7 +3685,7 @@ int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 		epb_string = "custom";
 		break;
 	}
-	fprintf(outf, "cpu%d: MSR_IA32_ENERGY_PERF_BIAS: 0x%08llx (%s)\n", cpu, msr, epb_string);
+	fprintf(outf, "cpu%d: EPB: %d (%s)\n", cpu, epb, epb_string);
 
 	return 0;
 }
-- 
2.21.0

[tip: x86/misc] tools/power/turbostat: Read energy_perf_bias from sysfs

[tip-bot2 for Borislav Petkov]

The following commit has been merged into the x86/misc branch of tip:

Commit-ID:     6d6501d912a9a5e1b73d7fbf419b90a8ec11ed7a
Gitweb:        https://git.kernel.org/tip/6d6501d912a9a5e1b73d7fbf419b90a8ec11ed7a
Author:        Borislav Petkov <bp@suse.de>
AuthorDate:    Thu, 15 Oct 2020 14:50:16 +02:00
Committer:     Borislav Petkov <bp@suse.de>
CommitterDate: Mon, 16 Nov 2020 17:42:46 +01:00

tools/power/turbostat: Read energy_perf_bias from sysfs

... instead of poking at the MSR directly.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-pm@vger.kernel.org
Link: https://lkml.kernel.org/r/20201029190259.3476-3-bp@alien8.de
---
 tools/power/x86/turbostat/turbostat.c | 29 +++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 33b3708..0baec7e 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -1721,6 +1721,25 @@ int get_mp(int cpu, struct msr_counter *mp, unsigned long long *counterp)
 	return 0;
 }
 
+int get_epb(int cpu)
+{
+	char path[128 + PATH_BYTES];
+	int ret, epb = -1;
+	FILE *fp;
+
+	sprintf(path, "/sys/devices/system/cpu/cpu%d/power/energy_perf_bias", cpu);
+
+	fp = fopen_or_die(path, "r");
+
+	ret = fscanf(fp, "%d", &epb);
+	if (ret != 1)
+		err(1, "%s(%s)", __func__, path);
+
+	fclose(fp);
+
+	return epb;
+}
+
 void get_apic_id(struct thread_data *t)
 {
 	unsigned int eax, ebx, ecx, edx;
@@ -3631,9 +3650,8 @@ dump_sysfs_pstate_config(void)
  */
 int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 {
-	unsigned long long msr;
 	char *epb_string;
-	int cpu;
+	int cpu, epb;
 
 	if (!has_epb)
 		return 0;
@@ -3649,10 +3667,11 @@ int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 		return -1;
 	}
 
-	if (get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr))
+	epb = get_epb(cpu);
+	if (epb < 0)
 		return 0;
 
-	switch (msr & 0xF) {
+	switch (epb) {
 	case ENERGY_PERF_BIAS_PERFORMANCE:
 		epb_string = "performance";
 		break;
@@ -3666,7 +3685,7 @@ int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 		epb_string = "custom";
 		break;
 	}
-	fprintf(outf, "cpu%d: MSR_IA32_ENERGY_PERF_BIAS: 0x%08llx (%s)\n", cpu, msr, epb_string);
+	fprintf(outf, "cpu%d: EPB: %d (%s)\n", cpu, epb, epb_string);
 
 	return 0;
 }

[PATCH v1 3/4] tools/power/x86_energy_perf_policy: Read energy_perf_bias from sysfs

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

... and stop poking at the MSR directly.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
 .../x86_energy_perf_policy.c                  | 109 ++++++++++++++++--
 1 file changed, 99 insertions(+), 10 deletions(-)

diff --git a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
index 3fe1eed900d4..ad6aed1fabf8 100644
--- a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
+++ b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
@@ -91,6 +91,9 @@ unsigned int has_hwp_request_pkg;	/* IA32_HWP_REQUEST_PKG */
 
 unsigned int bdx_highest_ratio;
 
+#define PATH_TO_CPU "/sys/devices/system/cpu/"
+#define SYSFS_PATH_MAX 255
+
 /*
  * maintain compatibility with original implementation, but don't document it:
  */
@@ -668,6 +671,48 @@ int put_msr(int cpu, int offset, unsigned long long new_msr)
 	return 0;
 }
 
+static unsigned int read_sysfs(const char *path, char *buf, size_t buflen)
+{
+	ssize_t numread;
+	int fd;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return 0;
+
+	numread = read(fd, buf, buflen - 1);
+	if (numread < 1) {
+		close(fd);
+		return 0;
+	}
+
+	buf[numread] = '\0';
+	close(fd);
+
+	return (unsigned int) numread;
+}
+
+static unsigned int write_sysfs(const char *path, char *buf, size_t buflen)
+{
+	ssize_t numwritten;
+	int fd;
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1)
+		return 0;
+
+	numwritten = write(fd, buf, buflen - 1);
+	if (numwritten < 1) {
+		perror("write failed\n");
+		close(fd);
+		return -1;
+	}
+
+	close(fd);
+
+	return (unsigned int) numwritten;
+}
+
 void print_hwp_cap(int cpu, struct msr_hwp_cap *cap, char *str)
 {
 	if (cpu != -1)
@@ -745,17 +790,61 @@ void write_hwp_request(int cpu, struct msr_hwp_request *hwp_req, unsigned int ms
 	put_msr(cpu, msr_offset, msr);
 }
 
+static int get_epb(int cpu)
+{
+	char path[SYSFS_PATH_MAX];
+	char linebuf[3];
+	char *endp;
+	long val;
+
+	if (!has_epb)
+		return -1;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu);
+
+	if (!read_sysfs(path, linebuf, 3))
+		return -1;
+
+	val = strtol(linebuf, &endp, 0);
+	if (endp == linebuf || errno == ERANGE)
+		return -1;
+
+	return (int)val;
+}
+
+static int set_epb(int cpu, int val)
+{
+	char path[SYSFS_PATH_MAX];
+	char linebuf[3];
+	char *endp;
+	int ret;
+
+	if (!has_epb)
+		return -1;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu);
+	snprintf(linebuf, sizeof(linebuf), "%d", val);
+
+	ret = write_sysfs(path, linebuf, 3);
+	if (ret <= 0)
+		return -1;
+
+	val = strtol(linebuf, &endp, 0);
+	if (endp == linebuf || errno == ERANGE)
+		return -1;
+
+	return (int)val;
+}
+
 int print_cpu_msrs(int cpu)
 {
-	unsigned long long msr;
 	struct msr_hwp_request req;
 	struct msr_hwp_cap cap;
+	int epb;
 
-	if (has_epb) {
-		get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr);
-
-		printf("cpu%d: EPB %u\n", cpu, (unsigned int) msr);
-	}
+	epb = get_epb(cpu);
+	if (epb >= 0)
+		printf("cpu%d: EPB %u\n", cpu, (unsigned int) epb);
 
 	if (!has_hwp)
 		return 0;
@@ -1038,15 +1127,15 @@ int enable_hwp_on_cpu(int cpu)
 int update_cpu_msrs(int cpu)
 {
 	unsigned long long msr;
-
+	int epb;
 
 	if (update_epb) {
-		get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr);
-		put_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, new_epb);
+		epb = get_epb(cpu);
+		set_epb(cpu, new_epb);
 
 		if (verbose)
 			printf("cpu%d: ENERGY_PERF_BIAS old: %d new: %d\n",
-				cpu, (unsigned int) msr, (unsigned int) new_epb);
+				cpu, epb, (unsigned int) new_epb);
 	}
 
 	if (update_turbo) {
-- 
2.21.0

[PATCH v1 4/4] x86/msr: Do not allow writes to MSR_IA32_ENERGY_PERF_BIAS

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

Now that all in-kernel-tree users are converted to using the sysfs file,
remove the MSR from the "allowlist".

Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/kernel/msr.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index c0d409810658..b1147862730c 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -99,9 +99,6 @@ static int filter_write(u32 reg)
 	if (!__ratelimit(&fw_rs))
 		return 0;
 
-	if (reg == MSR_IA32_ENERGY_PERF_BIAS)
-		return 0;
-
 	pr_err("Write to unrecognized MSR 0x%x by %s (pid: %d). Please report to x86@kernel.org.\n",
 	       reg, current->comm, current->pid);
 
-- 
2.21.0

Re: [PATCH v1 4/4] x86/msr: Do not allow writes to MSR_IA32_ENERGY_PERF_BIAS

[Shuah Khan]

On 10/29/20 1:02 PM, Borislav Petkov wrote:
> From: Borislav Petkov <bp@suse.de>
> 
> Now that all in-kernel-tree users are converted to using the sysfs file,
> remove the MSR from the "allowlist".
> 
> Signed-off-by: Borislav Petkov <bp@suse.de>
> ---
>   arch/x86/kernel/msr.c | 3 ---
>   1 file changed, 3 deletions(-)
> 
> diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
> index c0d409810658..b1147862730c 100644
> --- a/arch/x86/kernel/msr.c
> +++ b/arch/x86/kernel/msr.c
> @@ -99,9 +99,6 @@ static int filter_write(u32 reg)
>   	if (!__ratelimit(&fw_rs))
>   		return 0;
>   
> -	if (reg == MSR_IA32_ENERGY_PERF_BIAS)
> -		return 0;
> -
>   	pr_err("Write to unrecognized MSR 0x%x by %s (pid: %d). Please report to x86@kernel.org.\n",
>   	       reg, current->comm, current->pid);
>   
> 

Thanks. Looks good to me.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah