[dpdk-dev] [PATCH v5 03/10] eal: add intrinsics support check infrastructure

[Anatoly Burakov]

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 at intel.com>
---
 .../arm/include/rte_power_intrinsics.h        |  8 ++++++
 lib/librte_eal/arm/rte_cpuflags.c             |  6 +++++
 lib/librte_eal/include/generic/rte_cpuflags.h | 26 +++++++++++++++++++
 .../include/generic/rte_power_intrinsics.h    |  8 ++++++
 .../ppc/include/rte_power_intrinsics.h        |  8 ++++++
 lib/librte_eal/ppc/rte_cpuflags.c             |  6 +++++
 lib/librte_eal/rte_eal_version.map            |  1 +
 .../x86/include/rte_power_intrinsics.h        |  8 ++++++
 lib/librte_eal/x86/rte_cpuflags.c             | 12 +++++++++
 9 files changed, 83 insertions(+)

diff --git a/lib/librte_eal/arm/include/rte_power_intrinsics.h b/lib/librte_eal/arm/include/rte_power_intrinsics.h
index 4aad44a0b9..055ec5877a 100644
--- a/lib/librte_eal/arm/include/rte_power_intrinsics.h
+++ b/lib/librte_eal/arm/include/rte_power_intrinsics.h
@@ -17,6 +17,10 @@ extern "C" {
 /**
  * This function is not supported on ARM.
  *
+ * @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. Must be aligned on an 64-byte boundary.
  * @param expected_value
@@ -43,6 +47,10 @@ static inline void rte_power_monitor(const volatile void *p,
 /**
  * This function is not supported on ARM.
  *
+ * @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.
  *
diff --git a/lib/librte_eal/arm/rte_cpuflags.c b/lib/librte_eal/arm/rte_cpuflags.c
index caf3dc83a5..7eef11fa02 100644
--- a/lib/librte_eal/arm/rte_cpuflags.c
+++ b/lib/librte_eal/arm/rte_cpuflags.c
@@ -138,3 +138,9 @@ 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));
+}
diff --git a/lib/librte_eal/include/generic/rte_cpuflags.h b/lib/librte_eal/include/generic/rte_cpuflags.h
index 872f0ebe3e..28a5aecde8 100644
--- a/lib/librte_eal/include/generic/rte_cpuflags.h
+++ b/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
  */
diff --git a/lib/librte_eal/include/generic/rte_power_intrinsics.h b/lib/librte_eal/include/generic/rte_power_intrinsics.h
index e36c1f8976..218eda7e86 100644
--- a/lib/librte_eal/include/generic/rte_power_intrinsics.h
+++ b/lib/librte_eal/include/generic/rte_power_intrinsics.h
@@ -26,6 +26,10 @@
  * 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. Must be aligned on an 64-byte boundary.
  * @param expected_value
@@ -49,6 +53,10 @@ static inline void rte_power_monitor(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.
diff --git a/lib/librte_eal/ppc/include/rte_power_intrinsics.h b/lib/librte_eal/ppc/include/rte_power_intrinsics.h
index 70fd7b094f..d63ad86849 100644
--- a/lib/librte_eal/ppc/include/rte_power_intrinsics.h
+++ b/lib/librte_eal/ppc/include/rte_power_intrinsics.h
@@ -17,6 +17,10 @@ extern "C" {
 /**
  * This function is not supported on PPC64.
  *
+ * @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. Must be aligned on an 64-byte boundary.
  * @param expected_value
@@ -43,6 +47,10 @@ static inline void rte_power_monitor(const volatile void *p,
 /**
  * This function is not supported on PPC64.
  *
+ * @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.
  *
diff --git a/lib/librte_eal/ppc/rte_cpuflags.c b/lib/librte_eal/ppc/rte_cpuflags.c
index 3bb7563ce9..eee8234384 100644
--- a/lib/librte_eal/ppc/rte_cpuflags.c
+++ b/lib/librte_eal/ppc/rte_cpuflags.c
@@ -108,3 +108,9 @@ 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));
+}
diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index a93dea9fe6..ed944f2bd4 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -400,6 +400,7 @@ EXPERIMENTAL {
 	# added in 20.11
 	__rte_eal_trace_generic_size_t;
 	rte_service_lcore_may_be_active;
+	rte_cpu_get_intrinsics_support;
 };
 
 INTERNAL {
diff --git a/lib/librte_eal/x86/include/rte_power_intrinsics.h b/lib/librte_eal/x86/include/rte_power_intrinsics.h
index 8d579eaf64..3afc165a1f 100644
--- a/lib/librte_eal/x86/include/rte_power_intrinsics.h
+++ b/lib/librte_eal/x86/include/rte_power_intrinsics.h
@@ -29,6 +29,10 @@ extern "C" {
  * For more information about usage of these instructions, please refer to
  * Intel(R) 64 and IA-32 Architectures Software Developer's Manual.
  *
+ * @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. Must be aligned on an 64-byte boundary.
  * @param expected_value
@@ -80,6 +84,10 @@ static inline void rte_power_monitor(const volatile void *p,
  * information about usage of this instruction, please refer to Intel(R) 64 and
  * IA-32 Architectures Software Developer's Manual.
  *
+ * @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.
  *
diff --git a/lib/librte_eal/x86/rte_cpuflags.c b/lib/librte_eal/x86/rte_cpuflags.c
index 0325c4b93b..a96312ff7f 100644
--- a/lib/librte_eal/x86/rte_cpuflags.c
+++ b/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;
+	}
+}
-- 
2.17.1