From: Ville Syrjälä ville.syrjala@linux.intel.com
commit fc45e55ebc58dbf622cb89ddbf797589c7a5510b upstream.
The "safe state" index is used by acpi_idle_enter_bm() to avoid entering a C-state that may require bus mastering to be disabled on entry in the cases when this is not going to happen. For this reason, it should not be set to point to C3 type of C-states, because they may require bus mastering to be disabled on entry in principle.
This was broken by commit d6b88ce2eb9d ("ACPI: processor idle: Allow playing dead in C3 state") which inadvertently allowed the "safe state" index to point to C3 type of C-states.
This results in a machine that won't boot past the point when it first enters C3. Restore the correct behaviour (either demote to C1/C2, or use C3 but also set ARB_DIS=1).
I hit this on a Fujitsu Siemens Lifebook S6010 (P3) machine.
Fixes: d6b88ce2eb9d ("ACPI: processor idle: Allow playing dead in C3 state") Cc: 5.16+ stable@vger.kernel.org # 5.16+ Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com Tested-by: Woody Suwalski wsuwalski@gmail.com [ rjw: Subject and changelog adjustments ] Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/acpi/processor_idle.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -792,7 +792,8 @@ static int acpi_processor_setup_cstates( if (cx->type == ACPI_STATE_C1 || cx->type == ACPI_STATE_C2 || cx->type == ACPI_STATE_C3) { state->enter_dead = acpi_idle_play_dead; - drv->safe_state_index = count; + if (cx->type != ACPI_STATE_C3) + drv->safe_state_index = count; } /* * Halt-induced C1 is not good for ->enter_s2idle, because it