Commit 3d031d0d authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

Merge branch 'pm-cpuidle' 

Fix an issue in the PSCI cpuidle driver introduced recently and a nasty
x86 power regression introduced in 6.15:

 - Prevent freeing an uninitialized pointer in error path of
   dt_idle_state_present() in the PSCI cpuidle driver (Dan Carpenter).

 - Revert an x86 commit that went into 6.15 and caused idle power,
   including power in suspend-to-idle, to rise rather dramatically on
   systems booting with "nosmt" in the kernel command line (Rafael Wysocki).

* pm-cpuidle:
  Revert "x86/smp: Eliminate mwait_play_dead_cpuid_hint()"
  cpuidle: psci: Fix uninitialized variable in dt_idle_state_present()
parents 25961ae6 70523f33

arch/x86/kernel/smpboot.c

+47 −7
Original line number Diff line number Diff line
@@ -1244,10 +1244,6 @@ void play_dead_common(void) 
	local_irq_disable();

}



/*

 * We need to flush the caches before going to sleep, lest we have

 * dirty data in our caches when we come back up.

 */

void __noreturn mwait_play_dead(unsigned int eax_hint)

{

	struct mwait_cpu_dead *md = this_cpu_ptr(&mwait_cpu_dead);
@@ -1293,6 +1289,50 @@ void __noreturn mwait_play_dead(unsigned int eax_hint) 
	}

}



/*

 * We need to flush the caches before going to sleep, lest we have

 * dirty data in our caches when we come back up.

 */

static inline void mwait_play_dead_cpuid_hint(void)

{

	unsigned int eax, ebx, ecx, edx;

	unsigned int highest_cstate = 0;

	unsigned int highest_subcstate = 0;

	int i;



	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||

	    boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)

		return;

	if (!this_cpu_has(X86_FEATURE_MWAIT))

		return;

	if (!this_cpu_has(X86_FEATURE_CLFLUSH))

		return;



	eax = CPUID_LEAF_MWAIT;

	ecx = 0;

	native_cpuid(&eax, &ebx, &ecx, &edx);



	/*

	 * eax will be 0 if EDX enumeration is not valid.

	 * Initialized below to cstate, sub_cstate value when EDX is valid.

	 */

	if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED)) {

		eax = 0;

	} else {

		edx >>= MWAIT_SUBSTATE_SIZE;

		for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {

			if (edx & MWAIT_SUBSTATE_MASK) {

				highest_cstate = i;

				highest_subcstate = edx & MWAIT_SUBSTATE_MASK;

			}

		}

		eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |

			(highest_subcstate - 1);

	}



	mwait_play_dead(eax);

}



/*

 * Kick all "offline" CPUs out of mwait on kexec(). See comment in

 * mwait_play_dead().
@@ -1343,8 +1383,8 @@ void native_play_dead(void) 
	play_dead_common();

	tboot_shutdown(TB_SHUTDOWN_WFS);



	/* Below returns only on error. */

	cpuidle_play_dead();

	mwait_play_dead_cpuid_hint();

	if (cpuidle_play_dead())

		hlt_play_dead();

}

drivers/cpuidle/cpuidle-psci.c

+4 −5
Original line number Diff line number Diff line
@@ -456,14 +456,13 @@ static struct faux_device_ops psci_cpuidle_ops = { 


static bool __init dt_idle_state_present(void)

{

	struct device_node *cpu_node __free(device_node);

	struct device_node *state_node __free(device_node);



	cpu_node = of_cpu_device_node_get(cpumask_first(cpu_possible_mask));

	struct device_node *cpu_node __free(device_node) =

			of_cpu_device_node_get(cpumask_first(cpu_possible_mask));

	if (!cpu_node)

		return false;



	state_node = of_get_cpu_state_node(cpu_node, 0);

	struct device_node *state_node __free(device_node) =

			of_get_cpu_state_node(cpu_node, 0);

	if (!state_node)

		return false;