From: Giovanni Gherdovich ggherdovich@suse.cz
[ Upstream commit f4291df103315a696f0b8c4f45ca8ae773c17441 ]
Be defensive against the case where the processor reports a base_freq larger than turbo_freq (the ratio would be zero).
Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") Signed-off-by: Giovanni Gherdovich ggherdovich@suse.cz Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Link: https://lkml.kernel.org/r/20200531182453.15254-4-ggherdovich@suse.cz Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/smpboot.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 3917a2de1580c..e5b2b20a0aeee 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1974,6 +1974,7 @@ 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; @@ -2007,9 +2008,15 @@ 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; }