From: Rafael J. Wysocki Date: Mon, 5 Jun 2017 12:51:18 +0000 (+0200) Subject: cpufreq: intel_pstate: Avoid division by 0 in min_perf_pct_min() X-Git-Tag: v4.12-rc5~29^2^2 X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=57caf4ec2b8bfbcb4f738ab5a12eedf3a8786045;p=uclinux-h8%2Flinux.git cpufreq: intel_pstate: Avoid division by 0 in min_perf_pct_min() Commit c5a2ee7dde89 (cpufreq: intel_pstate: Active mode P-state limits rework) incorrectly assumed that pstate.turbo_pstate would always be nonzero for CPU0 in min_perf_pct_min() if cpufreq_register_driver() had succeeded which may not be the case in virtualized environments. If that assumption doesn't hold, it leads to an early crash on boot in intel_pstate_register_driver(), so add a sanity check to min_perf_pct_min() to prevent the crash from happening. Fixes: c5a2ee7dde89 (cpufreq: intel_pstate: Active mode P-state limits rework) Reported-and-tested-by: Jongman Heo Signed-off-by: Rafael J. Wysocki --- diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index b7de5bd76a31..eb1158532de3 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -571,9 +571,10 @@ static inline void update_turbo_state(void) static int min_perf_pct_min(void) { struct cpudata *cpu = all_cpu_data[0]; + int turbo_pstate = cpu->pstate.turbo_pstate; - return DIV_ROUND_UP(cpu->pstate.min_pstate * 100, - cpu->pstate.turbo_pstate); + return turbo_pstate ? + DIV_ROUND_UP(cpu->pstate.min_pstate * 100, turbo_pstate) : 0; } static s16 intel_pstate_get_epb(struct cpudata *cpu_data)