Commit 57caf4ec authored Jun 05, 2017 by Rafael J. Wysocki

cpufreq: intel_pstate: Avoid division by 0 in min_perf_pct_min()



Commit c5a2ee7d (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: c5a2ee7d (cpufreq: intel_pstate: Active mode P-state limits rework)
Reported-and-tested-by: Jongman Heo <jongman.heo@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent 33fc30b4

drivers/cpufreq/intel_pstate.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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)