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SubjectRe: [PATCH][rfc] intel_pstate: Fix user input of min/max to legal policy region
Date
On Wednesday, August 12, 2015 11:49:19 AM Chen Yu wrote:
> In current code, if system is using performance policy, user can
> modify the max_perf_pct to any values lower than 100:
>
> $ grep . /sys/devices/system/cpu/intel_pstate/m*_perf_pct
> /sys/devices/system/cpu/intel_pstate/max_perf_pct:100
> /sys/devices/system/cpu/intel_pstate/min_perf_pct:100
>
> $ echo 80 > /sys/devices/system/cpu/intel_pstate/max_perf_pct
>
> $ grep . /sys/devices/system/cpu/intel_pstate/m*_perf_pct
> /sys/devices/system/cpu/intel_pstate/max_perf_pct:80
> /sys/devices/system/cpu/intel_pstate/min_perf_pct:100
>
> the max_perf_pct above is lower than min_perf_pct, which
> is not reasonable.
>
> This patch solves this problem by clamping min_perf_pct and max_perf_pct
> to be strictly inside [min_policy_pct,max_policy_pct].
>
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>

Looks reasonable to me.

Kristen, any objections?


> ---
> drivers/cpufreq/intel_pstate.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index fcb929e..3702c5a 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -423,6 +423,7 @@ static ssize_t store_max_perf_pct(struct kobject *a, struct attribute *b,
>
> limits.max_sysfs_pct = clamp_t(int, input, 0 , 100);
> limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct);
> + limits.max_perf_pct = max(limits.min_policy_pct, limits.max_perf_pct);
> limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
>
> if (hwp_active)
> @@ -442,6 +443,7 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
>
> limits.min_sysfs_pct = clamp_t(int, input, 0 , 100);
> limits.min_perf_pct = max(limits.min_policy_pct, limits.min_sysfs_pct);
> + limits.min_perf_pct = min(limits.max_policy_pct, limits.min_perf_pct);
> limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
>
> if (hwp_active)
> @@ -985,12 +987,14 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
>
> limits.min_policy_pct = (policy->min * 100) / policy->cpuinfo.max_freq;
> limits.min_policy_pct = clamp_t(int, limits.min_policy_pct, 0 , 100);
> - limits.min_perf_pct = max(limits.min_policy_pct, limits.min_sysfs_pct);
> - limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
> -
> limits.max_policy_pct = (policy->max * 100) / policy->cpuinfo.max_freq;
> limits.max_policy_pct = clamp_t(int, limits.max_policy_pct, 0 , 100);
> +
> + limits.min_perf_pct = max(limits.min_policy_pct, limits.min_sysfs_pct);
> + limits.min_perf_pct = min(limits.max_policy_pct, limits.min_perf_pct);
> + limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
> limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct);
> + limits.max_perf_pct = max(limits.min_policy_pct, limits.max_perf_pct);
> limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
>
> if (hwp_active)
>

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.


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