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SubjectRe: [PATCH] [v2] intel_pstate: Fix user input of min/max to legal policy region
On Wed,  9 Sep 2015 18:27:31 +0800
Chen Yu <yu.c.chen@intel.com> wrote:

> In current code, max_perf_pct might be smaller than min_perf_pct
> by improper user input:
>
> $ 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
>
> Fix this problem by 2 steps:
> 1.Normalize the user input to [min_policy, max_policy].
> 2.Make sure max_perf_pct>=min_perf_pct, suggested by Seiichi Ikarashi.
>
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>

Acked-by: Kristen Carlson Accardi <kristen@linux.intel.com>
> ---
> v2:
> - Add logic to ensure max_perf_pct>=min_perf_pct.
> ---
> drivers/cpufreq/intel_pstate.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index fcb929e..a0b935f 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -423,6 +423,8 @@ 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_pct = max(limits.min_perf_pct, limits.max_perf_pct);
> limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
>
> if (hwp_active)
> @@ -442,6 +444,8 @@ 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_pct = min(limits.max_perf_pct, limits.min_perf_pct);
> limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
>
> if (hwp_active)
> @@ -985,12 +989,19 @@ 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);
> +
> + /* Normalize user input to [min_policy_pct, max_policy_pct] */
> + 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.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);
> +
> + /* Make sure min_perf_pct <= max_perf_pct */
> + limits.min_perf_pct = min(limits.max_perf_pct, limits.min_perf_pct);
> +
> + limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
> limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
>
> if (hwp_active)



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