Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux

intel_pstate: Set CPU number before accessing MSRs

Ensure that cpu->cpu is set before writing MSR_IA32_PERF_CTL during CPU
initialization. Otherwise only cpu0 has its P-state set and all other
cores are left with their values unchanged.

In most cases, this is not too serious because the P-states will be set
correctly when the timer function is run. But when the default governor
is set to performance, the per-CPU current_pstate stays the same forever
and no attempts are made to write the MSRs again.

Signed-off-by: Vincent Minet <vincent@vincent-minet.net>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

authored by

Vincent Minet and committed by
Rafael J. Wysocki
179e8471 41629a82

+1 -2
+1 -2
drivers/cpufreq/intel_pstate.c
··· 700 700 701 701 cpu = all_cpu_data[cpunum]; 702 702 703 - intel_pstate_get_cpu_pstates(cpu); 704 - 705 703 cpu->cpu = cpunum; 704 + intel_pstate_get_cpu_pstates(cpu); 706 705 707 706 init_timer_deferrable(&cpu->timer); 708 707 cpu->timer.function = intel_pstate_timer_func;