[dpdk-dev] [PATCH v4 01/17] eal: add max SIMD bitwidth

[Ciara Power <ciara.power@intel.com>]

This patch adds a max SIMD bitwidth EAL configuration. The API allows
for an app to set this value. It can also be set using EAL argument
--force-max-simd-bitwidth, which will lock the value and override any
modifications made by the app.

Each arch has a define for the default SIMD bitwidth value, this is used
on EAL init to set the config max SIMD bitwidth.

Cc: Ruifeng Wang <ruifeng.wang@arm.com>
Cc: Jerin Jacob <jerinj@marvell.com>
Cc: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Cc: David Christensen <drc@linux.vnet.ibm.com>

Signed-off-by: Ciara Power <ciara.power@intel.com>

---
v4:
  - Used RTE_SIMD_MAX instead of UINT16_MAX.
  - Renamed enums to better reflect usage.
  - Added functions to windows symbol export file.
  - Modified Doxygen comments.
  - Modified enum name.
  - Changed RTE_SIMD_MAX value to a power of 2.
  - Merged patch 2 into this patch.
  - Enum now used for default value defines.
  - Fixed some small comments on v3.
v3:
  - Added enum value to essentially disable using max SIMD to choose
    paths, intended for use by ARM SVE.
  - Fixed parsing bitwidth argument to return an error for values
    greater than uint16_t.
  - Removed unnecessary define in generic rte_vect.h
  - Changed default bitwidth for ARM to UINT16_MAX, to allow for SVE.
v2:
  - Added to Doxygen comment for API.
  - Changed default bitwidth for Arm to 128.
---
 lib/librte_eal/arm/include/rte_vect.h      |  2 +
 lib/librte_eal/common/eal_common_options.c | 66 ++++++++++++++++++++++
 lib/librte_eal/common/eal_internal_cfg.h   |  8 +++
 lib/librte_eal/common/eal_options.h        |  2 +
 lib/librte_eal/include/rte_eal.h           | 40 +++++++++++++
 lib/librte_eal/ppc/include/rte_vect.h      |  2 +
 lib/librte_eal/rte_eal_exports.def         |  2 +
 lib/librte_eal/rte_eal_version.map         |  2 +
 lib/librte_eal/x86/include/rte_vect.h      |  2 +
 9 files changed, 126 insertions(+)

diff --git a/lib/librte_eal/arm/include/rte_vect.h b/lib/librte_eal/arm/include/rte_vect.h
index 01c51712a1..f53c89be97 100644
--- a/lib/librte_eal/arm/include/rte_vect.h
+++ b/lib/librte_eal/arm/include/rte_vect.h
@@ -14,6 +14,8 @@
 extern "C" {
 #endif
 
+#define RTE_DEFAULT_SIMD_BITWIDTH RTE_SIMD_MAX
+
 typedef int32x4_t xmm_t;
 
 #define	XMM_SIZE	(sizeof(xmm_t))
diff --git a/lib/librte_eal/common/eal_common_options.c b/lib/librte_eal/common/eal_common_options.c
index a5426e1234..8c79f1b2fc 100644
--- a/lib/librte_eal/common/eal_common_options.c
+++ b/lib/librte_eal/common/eal_common_options.c
@@ -35,6 +35,7 @@
 #ifndef RTE_EXEC_ENV_WINDOWS
 #include <rte_telemetry.h>
 #endif
+#include <rte_vect.h>
 
 #include "eal_internal_cfg.h"
 #include "eal_options.h"
@@ -102,6 +103,7 @@ eal_long_options[] = {
 	{OPT_MATCH_ALLOCATIONS, 0, NULL, OPT_MATCH_ALLOCATIONS_NUM},
 	{OPT_TELEMETRY,         0, NULL, OPT_TELEMETRY_NUM        },
 	{OPT_NO_TELEMETRY,      0, NULL, OPT_NO_TELEMETRY_NUM     },
+	{OPT_FORCE_MAX_SIMD_BITWIDTH, 1, NULL, OPT_FORCE_MAX_SIMD_BITWIDTH_NUM},
 	{0,                     0, NULL, 0                        }
 };
 
@@ -343,6 +345,8 @@ eal_reset_internal_config(struct internal_config *internal_cfg)
 	internal_cfg->user_mbuf_pool_ops_name = NULL;
 	CPU_ZERO(&internal_cfg->ctrl_cpuset);
 	internal_cfg->init_complete = 0;
+	internal_cfg->max_simd_bitwidth.bitwidth = RTE_DEFAULT_SIMD_BITWIDTH;
+	internal_cfg->max_simd_bitwidth.forced = 0;
 }
 
 static int
@@ -1309,6 +1313,34 @@ eal_parse_iova_mode(const char *name)
 	return 0;
 }
 
+static int
+eal_parse_simd_bitwidth(const char *arg)
+{
+	char *end;
+	unsigned long bitwidth;
+	int ret;
+	struct internal_config *internal_conf =
+		eal_get_internal_configuration();
+
+	if (arg == NULL || arg[0] == '\0')
+		return -1;
+
+	errno = 0;
+	bitwidth = strtoul(arg, &end, 0);
+
+	/* check for errors */
+	if (errno != 0 || end == NULL || *end != '\0' || bitwidth > RTE_SIMD_MAX)
+		return -1;
+
+	if (bitwidth == 0)
+		bitwidth = (unsigned long) RTE_SIMD_MAX;
+	ret = rte_set_max_simd_bitwidth(bitwidth);
+	if (ret < 0)
+		return -1;
+	internal_conf->max_simd_bitwidth.forced = 1;
+	return 0;
+}
+
 static int
 eal_parse_base_virtaddr(const char *arg)
 {
@@ -1707,6 +1739,13 @@ eal_parse_common_option(int opt, const char *optarg,
 	case OPT_NO_TELEMETRY_NUM:
 		conf->no_telemetry = 1;
 		break;
+	case OPT_FORCE_MAX_SIMD_BITWIDTH_NUM:
+		if (eal_parse_simd_bitwidth(optarg) < 0) {
+			RTE_LOG(ERR, EAL, "invalid parameter for --"
+					OPT_FORCE_MAX_SIMD_BITWIDTH "\n");
+			return -1;
+		}
+		break;
 
 	/* don't know what to do, leave this to caller */
 	default:
@@ -1903,6 +1942,32 @@ eal_check_common_options(struct internal_config *internal_cfg)
 	return 0;
 }
 
+uint16_t
+rte_get_max_simd_bitwidth(void)
+{
+	const struct internal_config *internal_conf =
+		eal_get_internal_configuration();
+	return internal_conf->max_simd_bitwidth.bitwidth;
+}
+
+int
+rte_set_max_simd_bitwidth(uint16_t bitwidth)
+{
+	struct internal_config *internal_conf =
+		eal_get_internal_configuration();
+	if (internal_conf->max_simd_bitwidth.forced) {
+		RTE_LOG(NOTICE, EAL, "Cannot set max SIMD bitwidth - user runtime override enabled");
+		return -EPERM;
+	}
+
+	if (bitwidth < RTE_SIMD_DISABLED || !rte_is_power_of_2(bitwidth)) {
+		RTE_LOG(ERR, EAL, "Invalid bitwidth value!\n");
+		return -EINVAL;
+	}
+	internal_conf->max_simd_bitwidth.bitwidth = bitwidth;
+	return 0;
+}
+
 void
 eal_common_usage(void)
 {
@@ -1981,6 +2046,7 @@ eal_common_usage(void)
 	       "  --"OPT_BASE_VIRTADDR"     Base virtual address\n"
 	       "  --"OPT_TELEMETRY"   Enable telemetry support (on by default)\n"
 	       "  --"OPT_NO_TELEMETRY"   Disable telemetry support\n"
+	       "  --"OPT_FORCE_MAX_SIMD_BITWIDTH" Force the max SIMD bitwidth\n"
 	       "\nEAL options for DEBUG use only:\n"
 	       "  --"OPT_HUGE_UNLINK"       Unlink hugepage files after init\n"
 	       "  --"OPT_NO_HUGE"           Use malloc instead of hugetlbfs\n"
diff --git a/lib/librte_eal/common/eal_internal_cfg.h b/lib/librte_eal/common/eal_internal_cfg.h
index 13f93388a7..0c880cbe17 100644
--- a/lib/librte_eal/common/eal_internal_cfg.h
+++ b/lib/librte_eal/common/eal_internal_cfg.h
@@ -33,6 +33,12 @@ struct hugepage_info {
 	int lock_descriptor;    /**< file descriptor for hugepage dir */
 };
 
+struct simd_bitwidth {
+	bool forced;
+	/**< flag indicating if bitwidth is forced and can't be modified */
+	uint16_t bitwidth; /**< bitwidth value */
+};
+
 /**
  * internal configuration
  */
@@ -85,6 +91,8 @@ struct internal_config {
 	volatile unsigned int init_complete;
 	/**< indicates whether EAL has completed initialization */
 	unsigned int no_telemetry; /**< true to disable Telemetry */
+	struct simd_bitwidth max_simd_bitwidth;
+	/**< max simd bitwidth path to use */
 };
 
 void eal_reset_internal_config(struct internal_config *internal_cfg);
diff --git a/lib/librte_eal/common/eal_options.h b/lib/librte_eal/common/eal_options.h
index 89769d48b4..ef33979664 100644
--- a/lib/librte_eal/common/eal_options.h
+++ b/lib/librte_eal/common/eal_options.h
@@ -85,6 +85,8 @@ enum {
 	OPT_TELEMETRY_NUM,
 #define OPT_NO_TELEMETRY      "no-telemetry"
 	OPT_NO_TELEMETRY_NUM,
+#define OPT_FORCE_MAX_SIMD_BITWIDTH  "force-max-simd-bitwidth"
+	OPT_FORCE_MAX_SIMD_BITWIDTH_NUM,
 	OPT_LONG_MAX_NUM
 };
 
diff --git a/lib/librte_eal/include/rte_eal.h b/lib/librte_eal/include/rte_eal.h
index e3c2ef185e..706d3cca5a 100644
--- a/lib/librte_eal/include/rte_eal.h
+++ b/lib/librte_eal/include/rte_eal.h
@@ -43,6 +43,23 @@ enum rte_proc_type_t {
 	RTE_PROC_INVALID
 };
 
+/**
+ * The max SIMD bitwidth value to limit vector path selection.
+ */
+enum rte_max_simd {
+	RTE_SIMD_DISABLED = 64,
+	/**< Limits path selection to scalar, disables all vector paths. */
+	RTE_SIMD_128 = 128,
+	/**< Limits path selection to SSE/NEON/Altivec or below. */
+	RTE_SIMD_256 = 256, /**< Limits path selection to AVX2 or below. */
+	RTE_SIMD_512 = 512, /**< Limits path selection to AVX512 or below. */
+	RTE_SIMD_MAX = INT16_MAX + 1,
+	/**<
+	 * Disables limiting by max SIMD bitwidth, allows all suitable paths.
+	 * This value is used as it is a large number and a power of 2.
+	 */
+};
+
 /**
  * Get the process type in a multi-process setup
  *
@@ -51,6 +68,29 @@ enum rte_proc_type_t {
  */
 enum rte_proc_type_t rte_eal_process_type(void);
 
+/**
+ * Get the supported SIMD bitwidth.
+ *
+ * @return
+ *   uint16_t bitwidth.
+ */
+__rte_experimental
+uint16_t rte_get_max_simd_bitwidth(void);
+
+/**
+ * Set the supported SIMD bitwidth.
+ * This API should only be called once at initialization, before EAL init.
+ *
+ * @param bitwidth
+ *   uint16_t bitwidth.
+ * @return
+ *   - 0 on success.
+ *   - -EINVAL on invalid bitwidth parameter.
+ *   - -EPERM if bitwidth is forced.
+ */
+__rte_experimental
+int rte_set_max_simd_bitwidth(uint16_t bitwidth);
+
 /**
  * Request iopl privilege for all RPL.
  *
diff --git a/lib/librte_eal/ppc/include/rte_vect.h b/lib/librte_eal/ppc/include/rte_vect.h
index b0545c878c..a69aabc568 100644
--- a/lib/librte_eal/ppc/include/rte_vect.h
+++ b/lib/librte_eal/ppc/include/rte_vect.h
@@ -15,6 +15,8 @@
 extern "C" {
 #endif
 
+#define RTE_DEFAULT_SIMD_BITWIDTH RTE_SIMD_256
+
 typedef vector signed int xmm_t;
 
 #define	XMM_SIZE	(sizeof(xmm_t))
diff --git a/lib/librte_eal/rte_eal_exports.def b/lib/librte_eal/rte_eal_exports.def
index 7b35beb702..81e99b00d9 100644
--- a/lib/librte_eal/rte_eal_exports.def
+++ b/lib/librte_eal/rte_eal_exports.def
@@ -26,6 +26,7 @@ EXPORTS
 	rte_eal_tailq_register
 	rte_eal_using_phys_addrs
 	rte_free
+	rte_get_max_simd_bitwidth
 	rte_get_tsc_hz
 	rte_hexdump
 	rte_intr_rx_ctl
@@ -62,6 +63,7 @@ EXPORTS
 	rte_memzone_reserve_aligned
 	rte_memzone_reserve_bounded
 	rte_memzone_walk
+	rte_set_max_simd_bitwidth
 	rte_socket_id
 	rte_strerror
 	rte_strsplit
diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index a93dea9fe6..714be49377 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -400,6 +400,8 @@ EXPERIMENTAL {
 	# added in 20.11
 	__rte_eal_trace_generic_size_t;
 	rte_service_lcore_may_be_active;
+	rte_get_max_simd_bitwidth;
+	rte_set_max_simd_bitwidth;
 };
 
 INTERNAL {
diff --git a/lib/librte_eal/x86/include/rte_vect.h b/lib/librte_eal/x86/include/rte_vect.h
index df5a607623..a00d3d5a62 100644
--- a/lib/librte_eal/x86/include/rte_vect.h
+++ b/lib/librte_eal/x86/include/rte_vect.h
@@ -35,6 +35,8 @@
 extern "C" {
 #endif
 
+#define RTE_DEFAULT_SIMD_BITWIDTH RTE_SIMD_256
+
 typedef __m128i xmm_t;
 
 #define	XMM_SIZE	(sizeof(xmm_t))
-- 
2.22.0