6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Srinivas Pandruvada srinivas.pandruvada@linux.intel.com
[ Upstream commit 37b6ddba967c601479bea418a7ac6ff16b6232b7 ]
Setting global turbo flag based on CPU 0 P-state limits is problematic as it limits max P-state request on every CPU on the system just based on its P-state limits.
There are two cases in which global.turbo_disabled flag is set: - When the MSR_IA32_MISC_ENABLE_TURBO_DISABLE bit is set to 1 in the MSR MSR_IA32_MISC_ENABLE. This bit can be only changed by the system BIOS before power up. - When the max non turbo P-state is same as max turbo P-state for CPU 0.
The second check is not a valid to decide global turbo state based on the CPU 0. CPU 0 max turbo P-state can be same as max non turbo P-state, but for other CPUs this may not be true.
There is no guarantee that max P-state limits are same for every CPU. This is possible that during fusing max P-state for a CPU is constrained. Also with the Intel Speed Select performance profile, CPU 0 may not be present in all profiles. In this case the max non turbo and turbo P-state can be set to the lowest possible P-state by the hardware when switched to such profile. Since max non turbo and turbo P-state is same, global.turbo_disabled flag will be set.
Once global.turbo_disabled is set, any scaling max and min frequency update for any CPU will result in its max P-state constrained to the max non turbo P-state.
Hence remove the check of max non turbo P-state equal to max turbo P-state of CPU 0 to set global turbo disabled flag.
Signed-off-by: Srinivas Pandruvada srinivas.pandruvada@linux.intel.com [ rjw: Subject edit ] Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Stable-dep-of: ac4e04d9e378 ("cpufreq: intel_pstate: Unchecked MSR aceess in legacy mode") Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/cpufreq/intel_pstate.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)
--- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -595,13 +595,9 @@ static void intel_pstate_hybrid_hwp_adju static inline void update_turbo_state(void) { u64 misc_en; - struct cpudata *cpu;
- cpu = all_cpu_data[0]; rdmsrl(MSR_IA32_MISC_ENABLE, misc_en); - global.turbo_disabled = - (misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE || - cpu->pstate.max_pstate == cpu->pstate.turbo_pstate); + global.turbo_disabled = misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE; }
static int min_perf_pct_min(void)