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

Commit c5a2ee7dde (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: c5a2ee7dde (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>
hifive-unleashed-5.1
Rafael J. Wysocki 2017-06-05 14:51:18 +02:00
parent 33fc30b470
commit 57caf4ec2b
1 changed files with 3 additions and 2 deletions
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5
drivers/cpufreq/intel_pstate.c
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@ -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)