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

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

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

Hi all,

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.

Thx.

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 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..d2fa4bbecf74 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("write failed");
+		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 1/4] tools/power/cpupower: Read energy_perf_bias from sysfs

[Shuah Khan]

On 10/15/20 8:46 AM, 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(-)
> 
> diff --git a/tools/power/cpupower/lib/cpupower.c b/tools/power/cpupower/lib/cpupower.c
> index 3656e697537e..d2fa4bbecf74 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;
>   

Is there a reason to move "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("write failed");

Please add filename to the error message

> +		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);

Please add return check for snprintf, please add a define for
"cpu%u/power/energy_perf_bias" since it is hardcoded in
read/write functions.

> +
> +	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);

Please add return check for snprintf, please add a define for
"cpu%u/power/energy_perf_bias" since it is hardcoded in
read/write functions.

> +	snprintf(linebuf, sizeof(linebuf), "%d", val);

return value check?

> +
> +	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;
> 

thnaks,
-- Shuah

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

[Borislav Petkov]

On Thu, Oct 15, 2020 at 11:49:32AM -0600, Shuah Khan wrote:
> Is there a reason to move "int fd"?

Habit from tip - we sort function-local variables in a reverse fir tree
order. And since I'm adding cpupower_write_sysfs(), I made them look
consistent.

> > +	numwritten = write(fd, buf, buflen - 1);
> > +	if (numwritten < 1) {
> > +		perror("write failed");
> 
> Please add filename to the error message

	perror(path);

or do you want me to build a string with an error message and filename?

> Please add return check for snprintf, please add a define for
> "cpu%u/power/energy_perf_bias" since it is hardcoded in
> read/write functions.

None of the other snprintf() calls in cpupower do that. Nothing checks
snprintf() retval and the last part of the sysfs path is a naked string.

Why is this different?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

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

[Shuah Khan]

On 10/16/20 2:37 AM, Borislav Petkov wrote:
> On Thu, Oct 15, 2020 at 11:49:32AM -0600, Shuah Khan wrote:
>> Is there a reason to move "int fd"?
> 
Sorry for a late response.

Okay. Looked odd since it didn't need changing.

> Habit from tip - we sort function-local variables in a reverse fir tree
> order. And since I'm adding cpupower_write_sysfs(), I made them look
> consistent.
> 
>>> +	numwritten = write(fd, buf, buflen - 1);
>>> +	if (numwritten < 1) {
>>> +		perror("write failed");
>>
>> Please add filename to the error message
> 
> 	perror(path);
> 
> or do you want me to build a string with an error message and filename?

Right. It will be great if you can add filename to the message.
> 
>> Please add return check for snprintf, please add a define for
>> "cpu%u/power/energy_perf_bias" since it is hardcoded in
>> read/write functions.
> 
> None of the other snprintf() calls in cpupower do that. Nothing checks
> snprintf() retval and the last part of the sysfs path is a naked string.
> 
> Why is this different?
> 

All of the other ones should be changed as such. Why add more?

thanks,
-- Shuah

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

[Borislav Petkov]

On Thu, Oct 29, 2020 at 03:38:43PM -0600, Shuah Khan wrote:
> All of the other ones should be changed as such. Why add more?

Because a patch should do one thing and one thing only. So a separate
patch which converts them all in one go should come ontop. But if you
insist for the ones I'm adding to have error handling, I can do that, of
course.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

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

[Shuah Khan]

On 10/29/20 3:59 PM, Borislav Petkov wrote:
> On Thu, Oct 29, 2020 at 03:38:43PM -0600, Shuah Khan wrote:
>> All of the other ones should be changed as such. Why add more?
> 
> Because a patch should do one thing and one thing only. So a separate
> patch which converts them all in one go should come ontop. But if you
> insist for the ones I'm adding to have error handling, I can do that, of
> course.
> 

A separate patch is fine.


if (numwritten < 1) {
+        perror("write failed");

Please add filename to the error message.

Thanks. Since this depends on other changes, it can go through
tip once this error message change is made.

thanks,
-- Shuah

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

[Borislav Petkov]

On Thu, Oct 29, 2020 at 04:32:43PM -0600, Shuah Khan wrote:
> if (numwritten < 1) {
> +        perror("write failed");
> 
> Please add filename to the error message.

Yes, you said so already and will do that in the next version.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

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

[Borislav Petkov]

On Thu, Oct 29, 2020 at 04:32:43PM -0600, Shuah Khan wrote:
> > Because a patch should do one thing and one thing only. So a separate
> > patch which converts them all in one go should come ontop. But if you
> > insist for the ones I'm adding to have error handling, I can do that, of
> > course.
> > 
> 
> A separate patch is fine.

Here's how it could look like, I've converted two users for now to get
your opinion first before I convert the rest.

Thx.

---
diff --git a/tools/power/cpupower/bench/Makefile b/tools/power/cpupower/bench/Makefile
index f68b4bc55273..d4ac380f7a56 100644
--- a/tools/power/cpupower/bench/Makefile
+++ b/tools/power/cpupower/bench/Makefile
@@ -9,13 +9,14 @@ endif
 ifeq ($(strip $(STATIC)),true)
 LIBS = -L../ -L$(OUTPUT) -lm
 OBJS = $(OUTPUT)main.o $(OUTPUT)parse.o $(OUTPUT)system.o $(OUTPUT)benchmark.o \
-       $(OUTPUT)../lib/cpufreq.o $(OUTPUT)../lib/cpupower.o
+       $(OUTPUT)../lib/cpufreq.o $(OUTPUT)../lib/cpupower.o $(OUTPUT)../utils/helpers/string.o
 else
 LIBS = -L../ -L$(OUTPUT) -lm -lcpupower
-OBJS = $(OUTPUT)main.o $(OUTPUT)parse.o $(OUTPUT)system.o $(OUTPUT)benchmark.o
+OBJS = $(OUTPUT)main.o $(OUTPUT)parse.o $(OUTPUT)system.o $(OUTPUT)benchmark.o \
+       $(OUTPUT)../utils/helpers/string.o
 endif
 
-CFLAGS += -D_GNU_SOURCE -I../lib -DDEFAULT_CONFIG_FILE=\"$(confdir)/cpufreq-bench.conf\"
+CFLAGS += -D_GNU_SOURCE -I../lib -I../utils -DDEFAULT_CONFIG_FILE=\"$(confdir)/cpufreq-bench.conf\"
 
 $(OUTPUT)%.o : %.c
 	$(ECHO) "  CC      " $@
diff --git a/tools/power/cpupower/bench/parse.c b/tools/power/cpupower/bench/parse.c
index e63dc11fa3a5..54ba48ad0983 100644
--- a/tools/power/cpupower/bench/parse.c
+++ b/tools/power/cpupower/bench/parse.c
@@ -18,6 +18,8 @@
 #include "parse.h"
 #include "config.h"
 
+#include "helpers/helpers.h"
+
 /**
  * converts priority string to priority
  *
@@ -84,11 +86,12 @@ FILE *prepare_output(const char *dirname)
 		}
 
 		filename = filename_tmp;
-		snprintf(filename, len - 1, "%s/benchmark_%s_%s_%li.log",
-			dirname, sysdata.nodename, sysdata.release, time(NULL));
+		if (!cpupower_snprintf(filename, len - 1, "%s/benchmark_%s_%s_%li.log",
+		    dirname, sysdata.nodename, sysdata.release, time(NULL)))
+			return NULL;
 	} else {
-		snprintf(filename, len - 1, "%s/benchmark_%li.log",
-			dirname, time(NULL));
+		if (!cpupower_snprintf(filename, len - 1, "%s/benchmark_%li.log", dirname, time(NULL)))
+			return NULL;
 	}
 
 	dprintf("logfilename: %s\n", filename);
diff --git a/tools/power/cpupower/utils/helpers/helpers.h b/tools/power/cpupower/utils/helpers/helpers.h
index 37dac161f3fe..dadd919ee599 100644
--- a/tools/power/cpupower/utils/helpers/helpers.h
+++ b/tools/power/cpupower/utils/helpers/helpers.h
@@ -171,4 +171,6 @@ static inline unsigned int cpuid_ecx(unsigned int op) { return 0; };
 static inline unsigned int cpuid_edx(unsigned int op) { return 0; };
 #endif /* defined(__i386__) || defined(__x86_64__) */
 
+extern char *cpupower_snprintf(char *str, int size, const char *fmt, ...);
+
 #endif /* __CPUPOWERUTILS_HELPERS__ */
diff --git a/tools/power/cpupower/utils/helpers/string.c b/tools/power/cpupower/utils/helpers/string.c
new file mode 100644
index 000000000000..bbd5e90bdc6e
--- /dev/null
+++ b/tools/power/cpupower/utils/helpers/string.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+
+#include "helpers/helpers.h"
+
+/*
+ * A helper with error handling for less code clutter.
+ */
+char *cpupower_snprintf(char *str, int size, const char *fmt, ...)
+{
+	int sz = 0;
+	va_list ap;
+
+	va_start(ap, fmt);
+	sz = vsnprintf(str, size, fmt, ap);
+	va_end(ap);
+
+	if (sz < 0) {
+		perror("vsnprintf");
+		return NULL;
+	}
+
+	if (sz >= size) {
+		fprintf(stderr, "Output truncated: [%s]\n", str);
+		return NULL;
+	}
+
+	return str;
+}

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

[PATCH 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

[PATCH 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 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