| From 3b5203e4cd5ca2447a4ae74ca7a1e034474438f3 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Sun, 31 May 2020 20:24:53 +0200 |
| Subject: x86, sched: Bail out of frequency invariance if turbo_freq/base_freq |
| gives 0 |
| |
| 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; |
| } |
| |
| -- |
| 2.25.1 |
| |