[PATCH 1/9] cpuidle: rename ARCH_HAS_CPU_RELAX to ARCH_HAS_OPTIMIZED_POLL

[Ankur Arora]

ARCH_HAS_CPU_RELAX is a bit of a misnomer since all architectures
define cpu_relax(). Not all, however, have a performant version, with
some only implementing it as a compiler barrier.

In contexts that this config option is used, it is expected to provide
an architectural primitive that can be used as part of a polling
mechanism -- one that would be cheaper than spinning in a tight loop.

Advertise the availability of such a primitive by renaming to
ARCH_HAS_OPTIMIZED_POLL. And, while at it, explicitly condition
cpuidle-haltpoll and intel-idle, both of which depend on a polling
state, on it.

Suggested-by: Will Deacon <will at kernel.org>
Signed-off-by: Ankur Arora <ankur.a.arora at oracle.com>
---
 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 4474bf32d0a4..b238c874875a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -368,7 +368,7 @@ 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 bd6a7857ce05..ccef38410950 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -36,7 +36,7 @@
 #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);
@@ -787,7 +787,7 @@ 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) {}
-- 
2.39.3