Commit f4291df1 authored by Giovanni Gherdovich's avatar Giovanni Gherdovich Committed by Peter Zijlstra
Browse files

x86, sched: Bail out of frequency invariance if turbo_freq/base_freq gives 0 



Be defensive against the case where the processor reports a base_freq
larger than turbo_freq (the ratio would be zero).

Fixes: 1567c3e3 ("x86, sched: Add support for frequency invariance")
Signed-off-by: default avatarGiovanni Gherdovich <ggherdovich@suse.cz>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lkml.kernel.org/r/20200531182453.15254-4-ggherdovich@suse.cz
parent 51beea88

arch/x86/kernel/smpboot.c

+9 −2
Original line number Diff line number Diff line
@@ -1977,6 +1977,7 @@ static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq) 
static bool intel_set_max_freq_ratio(void)

{

	u64 base_freq, turbo_freq;

	u64 turbo_ratio;



	if (slv_set_max_freq_ratio(&base_freq, &turbo_freq))

		goto out;
@@ -2010,9 +2011,15 @@ static bool intel_set_max_freq_ratio(void) 
		return false;

	}



	arch_turbo_freq_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE,

					base_freq);

	turbo_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq);

	if (!turbo_ratio) {

		pr_debug("Non-zero turbo and base frequencies led to a 0 ratio.\n");

		return false;

	}



	arch_turbo_freq_ratio = turbo_ratio;

	arch_set_max_freq_ratio(turbo_disabled());



	return true;

}