ARCH_HAS_CPU_RELAX is defined on architectures that provide an
primitive (via cpu_relax()) that can be used as part of a polling
mechanism -- one that would be cheaper than spinning in a tight
loop.
However, recent changes in poll_idle() mean that a higher level
primitive -- smp_cond_load_relaxed() is used for polling. This would
in-turn use cpu_relax() or an architecture specific implementation.
On ARM64 in particular this turns into a WFE which waits on a store
to a cacheline instead of a busy poll.
Accordingly condition the polling drivers on ARCH_HAS_OPTIMIZED_POLL
instead of ARCH_HAS_CPU_RELAX. While at it, make both intel-idle
and cpuidle-haltpoll explicitly depend on ARCH_HAS_CPU_RELAX.
Suggested-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Ankur Arora <ankur.a.arora@xxxxxxxxxx>
---
arch/x86/Kconfig | 2 +-
drivers/acpi/processor_idle.c | 4 ++--
drivers/cpuidle/Kconfig | 2 +-
drivers/cpuidle/Makefile | 2 +-
drivers/idle/Kconfig | 1 +
include/linux/cpuidle.h | 2 +-
6 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2852fcd82cbd..555871e7e3b2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -378,7 +378,7 @@ config ARCH_MAY_HAVE_PC_FDC
config GENERIC_CALIBRATE_DELAY
def_bool y
-config ARCH_HAS_CPU_RELAX
+config ARCH_HAS_OPTIMIZED_POLL
def_bool y
config ARCH_HIBERNATION_POSSIBLE
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 831fa4a12159..44096406d65d 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -35,7 +35,7 @@
#include <asm/cpu.h>
#endif
-#define ACPI_IDLE_STATE_START (IS_ENABLED(CONFIG_ARCH_HAS_CPU_RELAX) ? 1 : 0)
+#define ACPI_IDLE_STATE_START (IS_ENABLED(CONFIG_ARCH_HAS_OPTIMIZED_POLL) ? 1 : 0)
static unsigned int max_cstate __read_mostly = ACPI_PROCESSOR_MAX_POWER;
module_param(max_cstate, uint, 0400);
@@ -782,7 +782,7 @@ static int acpi_processor_setup_cstates(struct acpi_processor *pr)
if (max_cstate == 0)
max_cstate = 1;
- if (IS_ENABLED(CONFIG_ARCH_HAS_CPU_RELAX)) {
+ if (IS_ENABLED(CONFIG_ARCH_HAS_OPTIMIZED_POLL)) {
cpuidle_poll_state_init(drv);
count = 1;
} else {
diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index cac5997dca50..75f6e176bbc8 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -73,7 +73,7 @@ endmenu
config HALTPOLL_CPUIDLE
tristate "Halt poll cpuidle driver"
- depends on X86 && KVM_GUEST
+ depends on X86 && KVM_GUEST && ARCH_HAS_OPTIMIZED_POLL
select CPU_IDLE_GOV_HALTPOLL
default y
help
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index d103342b7cfc..f29dfd1525b0 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -7,7 +7,7 @@ obj-y += cpuidle.o driver.o governor.o sysfs.o governors/
obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
obj-$(CONFIG_DT_IDLE_STATES) += dt_idle_states.o
obj-$(CONFIG_DT_IDLE_GENPD) += dt_idle_genpd.o
-obj-$(CONFIG_ARCH_HAS_CPU_RELAX) += poll_state.o
+obj-$(CONFIG_ARCH_HAS_OPTIMIZED_POLL) += poll_state.o
obj-$(CONFIG_HALTPOLL_CPUIDLE) += cpuidle-haltpoll.o
##################################################################################
diff --git a/drivers/idle/Kconfig b/drivers/idle/Kconfig
index 6707d2539fc4..6f9b1d48fede 100644
--- a/drivers/idle/Kconfig
+++ b/drivers/idle/Kconfig
@@ -4,6 +4,7 @@ config INTEL_IDLE
depends on CPU_IDLE
depends on X86
depends on CPU_SUP_INTEL
+ depends on ARCH_HAS_OPTIMIZED_POLL
help
Enable intel_idle, a cpuidle driver that includes knowledge of
native Intel hardware idle features. The acpi_idle driver
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 3183aeb7f5b4..7e7e58a17b07 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -275,7 +275,7 @@ static inline void cpuidle_coupled_parallel_barrier(struct cpuidle_device *dev,
}
#endif
-#if defined(CONFIG_CPU_IDLE) && defined(CONFIG_ARCH_HAS_CPU_RELAX)
+#if defined(CONFIG_CPU_IDLE) && defined(CONFIG_ARCH_HAS_OPTIMIZED_POLL)
void cpuidle_poll_state_init(struct cpuidle_driver *drv);
#else
static inline void cpuidle_poll_state_init(struct cpuidle_driver *drv) {}
--
2.43.5
