5.15-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Gleixner tglx@linutronix.de
commit c157d351460bcf202970e97e611cb6b54a3dd4a4 upstream.
The Intel idle driver is preferred over the ACPI processor idle driver, but fails to implement the work around for Core2 generation CPUs, where the TSC stops in C2 and deeper C-states. This causes stalls and boot delays, when the clocksource watchdog does not catch the unstable TSC before the CPU goes deep idle for the first time.
The ACPI driver marks the TSC unstable when it detects that the CPU supports C2 or deeper and the CPU does not have a non-stop TSC.
Add the equivivalent work around to the Intel idle driver to cure that.
Fixes: 18734958e9bf ("intel_idle: Use ACPI _CST for processor models without C-state tables") Reported-by: Fab Stz fabstz-it@yahoo.fr Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Fab Stz fabstz-it@yahoo.fr Cc: All applicable stable@vger.kernel.org Closes: https://lore.kernel.org/all/10cf96aa-1276-4bd4-8966-c890377030c3@yahoo.fr Link: https://patch.msgid.link/87bjupfy7f.ffs@tglx Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/idle/intel_idle.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -56,6 +56,7 @@ #include <asm/nospec-branch.h> #include <asm/mwait.h> #include <asm/msr.h> +#include <asm/tsc.h>
#define INTEL_IDLE_VERSION "0.5.1"
@@ -1335,6 +1336,9 @@ static void __init intel_idle_init_cstat if (intel_idle_state_needs_timer_stop(state)) state->flags |= CPUIDLE_FLAG_TIMER_STOP;
+ if (cx->type > ACPI_STATE_C1 && !boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) + mark_tsc_unstable("TSC halts in idle"); + state->enter = intel_idle; state->enter_s2idle = intel_idle_s2idle; }