eal: add intrinsics support check infrastructure

Currently, it is not possible to check support for intrinsics that
are platform-specific, cannot be abstracted in a generic way, or do not
have support on all architectures. The CPUID flags can be used to some
extent, but they are only defined for their platform, while intrinsics
will be available to all code as they are in generic headers.

This patch introduces infrastructure to check support for certain
platform-specific intrinsics, and adds support for checking support for
IA power management-related intrinsics for UMWAIT/UMONITOR and TPAUSE.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Signed-off-by: Liang Ma <liang.j.ma@intel.com>
Acked-by: David Christensen <drc@linux.vnet.ibm.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>
Acked-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Ray Kinsella <mdr@ashroe.eu>

lib/librte_eal/arm/rte_cpuflags.c

@@ -151,3 +151,9 @@ rte_cpu_get_flag_name(enum rte_cpu_flag_t feature)
 		return NULL;
 	return rte_cpu_feature_table[feature].name;
 }
+
+void
+rte_cpu_get_intrinsics_support(struct rte_cpu_intrinsics *intrinsics)
+{
+	memset(intrinsics, 0, sizeof(*intrinsics));
+}

lib/librte_eal/include/generic/rte_cpuflags.h

@@ -13,6 +13,32 @@
 #include "rte_common.h"
 #include <errno.h>
 
+#include <rte_compat.h>
+
+/**
+ * Structure used to describe platform-specific intrinsics that may or may not
+ * be supported at runtime.
+ */
+struct rte_cpu_intrinsics {
+	uint32_t power_monitor : 1;
+	/**< indicates support for rte_power_monitor function */
+	uint32_t power_pause : 1;
+	/**< indicates support for rte_power_pause function */
+};
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Check CPU support for various intrinsics at runtime.
+ *
+ * @param intrinsics
+ *     Pointer to a structure to be filled.
+ */
+__rte_experimental
+void
+rte_cpu_get_intrinsics_support(struct rte_cpu_intrinsics *intrinsics);
+
 /**
  * Enumeration of all CPU features supported
  */

lib/librte_eal/include/generic/rte_power_intrinsics.h

@@ -32,6 +32,10 @@
  * checked against the expected value, and if they match, the entering of
  * optimized power state may be aborted.
  *
+ * @warning It is responsibility of the user to check if this function is
+ *   supported at runtime using `rte_cpu_get_features()` API call.
+ *   Failing to do so may result in an illegal CPU instruction error.
+ *
  * @param p
  *   Address to monitor for changes.
  * @param expected_value
@@ -69,6 +73,10 @@ static inline void rte_power_monitor(const volatile void *p,
  * This call will also lock a spinlock on entering sleep, and release it on
  * waking up the CPU.
  *
+ * @warning It is responsibility of the user to check if this function is
+ *   supported at runtime using `rte_cpu_get_features()` API call.
+ *   Failing to do so may result in an illegal CPU instruction error.
+ *
  * @param p
  *   Address to monitor for changes.
  * @param expected_value
@@ -101,6 +109,10 @@ static inline void rte_power_monitor_sync(const volatile void *p,
  * Enter an architecture-defined optimized power state until a certain TSC
  * timestamp is reached.
  *
+ * @warning It is responsibility of the user to check if this function is
+ *   supported at runtime using `rte_cpu_get_features()` API call.
+ *   Failing to do so may result in an illegal CPU instruction error.
+ *
  * @param tsc_timestamp
  *   Maximum TSC timestamp to wait for. Note that the wait behavior is
  *   architecture-dependent.

lib/librte_eal/ppc/rte_cpuflags.c

@@ -8,6 +8,7 @@
 #include <elf.h>
 #include <fcntl.h>
 #include <assert.h>
+#include <string.h>
 #include <unistd.h>
 
 /* Symbolic values for the entries in the auxiliary table */
@@ -108,3 +109,9 @@ rte_cpu_get_flag_name(enum rte_cpu_flag_t feature)
 		return NULL;
 	return rte_cpu_feature_table[feature].name;
 }
+
+void
+rte_cpu_get_intrinsics_support(struct rte_cpu_intrinsics *intrinsics)
+{
+	memset(intrinsics, 0, sizeof(*intrinsics));
+}

lib/librte_eal/version.map

@@ -398,6 +398,7 @@ EXPERIMENTAL {
 
 	# added in 20.11
 	__rte_eal_trace_generic_size_t;
+	rte_cpu_get_intrinsics_support;
 	rte_epoll_wait_interruptible;
 	rte_service_lcore_may_be_active;
 	rte_vect_get_max_simd_bitwidth;

lib/librte_eal/x86/rte_cpuflags.c

@@ -7,6 +7,7 @@
 #include <stdio.h>
 #include <errno.h>
 #include <stdint.h>
+#include <string.h>
 
 #include "rte_cpuid.h"
 
@@ -179,3 +180,14 @@ rte_cpu_get_flag_name(enum rte_cpu_flag_t feature)
 		return NULL;
 	return rte_cpu_feature_table[feature].name;
 }
+
+void
+rte_cpu_get_intrinsics_support(struct rte_cpu_intrinsics *intrinsics)
+{
+	memset(intrinsics, 0, sizeof(*intrinsics));
+
+	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_WAITPKG)) {
+		intrinsics->power_monitor = 1;
+		intrinsics->power_pause = 1;
+	}
+}