[dpdk-dev] [PATCH v8 16/18] net: add checks for max SIMD bitwidth

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

When choosing a vector path to take, an extra condition must be
satisfied to ensure the max SIMD bitwidth allows for the CPU enabled
path.

The vector path was initially chosen in RTE_INIT, however this is no
longer suitable as we cannot check the max SIMD bitwidth at that time.
Default handlers are now chosen on initialisation, these default
handlers are used the first time the crc calc is called, and they set
the suitable handlers to be used going forward.

Suggested-by: Jasvinder Singh <jasvinder.singh@intel.com>
Suggested-by: Olivier Matz <olivier.matz@6wind.com>

Signed-off-by: Ciara Power <ciara.power@intel.com>
Acked-by: Jasvinder Singh <jasvinder.singh@intel.com>

---
v7: Removed unnecessary log variable.
v6:
  - Moved log variable and macro to c file instead of public header.
  - Added the max_simd_bitwidth condition check to the recently added
    handler helper functions.
  - Modified default handlers to follow the approach of the set alg
    function.
v4:
  - Added default handlers to be set at RTE_INIT time, rather than
    choosing scalar handlers.
  - Modified logging.
  - Updated enum name.
v3:
  - Moved choosing vector paths out of RTE_INIT.
  - Moved checking max_simd_bitwidth into the set_alg function.
---
 lib/librte_net/rte_net_crc.c | 116 +++++++++++++++++++++++++----------
 1 file changed, 85 insertions(+), 31 deletions(-)

diff --git a/lib/librte_net/rte_net_crc.c b/lib/librte_net/rte_net_crc.c
index 32a3665908..c2ff82bbd6 100644
--- a/lib/librte_net/rte_net_crc.c
+++ b/lib/librte_net/rte_net_crc.c
@@ -9,6 +9,8 @@
 #include <rte_cpuflags.h>
 #include <rte_common.h>
 #include <rte_net_crc.h>
+#include <rte_eal.h>
+#include <rte_log.h>
 
 #include "net_crc.h"
 
@@ -22,6 +24,12 @@
 static uint32_t crc32_eth_lut[CRC_LUT_SIZE];
 static uint32_t crc16_ccitt_lut[CRC_LUT_SIZE];
 
+static uint32_t
+rte_crc16_ccitt_default_handler(const uint8_t *data, uint32_t data_len);
+
+static uint32_t
+rte_crc32_eth_default_handler(const uint8_t *data, uint32_t data_len);
+
 static uint32_t
 rte_crc16_ccitt_handler(const uint8_t *data, uint32_t data_len);
 
@@ -31,7 +39,12 @@ rte_crc32_eth_handler(const uint8_t *data, uint32_t data_len);
 typedef uint32_t
 (*rte_net_crc_handler)(const uint8_t *data, uint32_t data_len);
 
-static const rte_net_crc_handler *handlers;
+static rte_net_crc_handler handlers_default[] = {
+	[RTE_NET_CRC16_CCITT] = rte_crc16_ccitt_default_handler,
+	[RTE_NET_CRC32_ETH] = rte_crc32_eth_default_handler,
+};
+
+static const rte_net_crc_handler *handlers = handlers_default;
 
 static const rte_net_crc_handler handlers_scalar[] = {
 	[RTE_NET_CRC16_CCITT] = rte_crc16_ccitt_handler,
@@ -56,6 +69,14 @@ static const rte_net_crc_handler handlers_neon[] = {
 };
 #endif
 
+static uint16_t max_simd_bitwidth;
+
+#define NET_LOG(level, fmt, args...)					\
+	rte_log(RTE_LOG_ ## level, libnet_logtype, "%s(): " fmt "\n",	\
+		__func__, ## args)
+
+RTE_LOG_REGISTER(libnet_logtype, lib.net, INFO);
+
 /* Scalar handling */
 
 /**
@@ -155,22 +176,21 @@ static const rte_net_crc_handler *
 avx512_vpclmulqdq_get_handlers(void)
 {
 #ifdef CC_X86_64_AVX512_VPCLMULQDQ_SUPPORT
-	if (AVX512_VPCLMULQDQ_CPU_SUPPORTED)
+	if (AVX512_VPCLMULQDQ_CPU_SUPPORTED &&
+			max_simd_bitwidth >= RTE_SIMD_512)
 		return handlers_avx512;
 #endif
+	NET_LOG(INFO, "Requirements not met, can't use AVX512\n");
 	return NULL;
 }
 
-static uint8_t
+static void
 avx512_vpclmulqdq_init(void)
 {
 #ifdef CC_X86_64_AVX512_VPCLMULQDQ_SUPPORT
-	if (AVX512_VPCLMULQDQ_CPU_SUPPORTED) {
+	if (AVX512_VPCLMULQDQ_CPU_SUPPORTED)
 		rte_net_crc_avx512_init();
-		return 1;
-	}
 #endif
-	return 0;
 }
 
 /* SSE4.2/PCLMULQDQ handling */
@@ -182,22 +202,21 @@ static const rte_net_crc_handler *
 sse42_pclmulqdq_get_handlers(void)
 {
 #ifdef CC_X86_64_SSE42_PCLMULQDQ_SUPPORT
-	if (SSE42_PCLMULQDQ_CPU_SUPPORTED)
+	if (SSE42_PCLMULQDQ_CPU_SUPPORTED &&
+			max_simd_bitwidth >= RTE_SIMD_128)
 		return handlers_sse42;
 #endif
+	NET_LOG(INFO, "Requirements not met, can't use SSE\n");
 	return NULL;
 }
 
-static uint8_t
+static void
 sse42_pclmulqdq_init(void)
 {
 #ifdef CC_X86_64_SSE42_PCLMULQDQ_SUPPORT
-	if (SSE42_PCLMULQDQ_CPU_SUPPORTED) {
+	if (SSE42_PCLMULQDQ_CPU_SUPPORTED)
 		rte_net_crc_sse42_init();
-		return 1;
-	}
 #endif
-	return 0;
 }
 
 /* NEON/PMULL handling */
@@ -209,22 +228,63 @@ static const rte_net_crc_handler *
 neon_pmull_get_handlers(void)
 {
 #ifdef CC_ARM64_NEON_PMULL_SUPPORT
-	if (NEON_PMULL_CPU_SUPPORTED)
+	if (NEON_PMULL_CPU_SUPPORTED &&
+			max_simd_bitwidth >= RTE_SIMD_128)
 		return handlers_neon;
 #endif
+	NET_LOG(INFO, "Requirements not met, can't use NEON\n");
 	return NULL;
 }
 
-static uint8_t
+static void
 neon_pmull_init(void)
 {
 #ifdef CC_ARM64_NEON_PMULL_SUPPORT
-	if (NEON_PMULL_CPU_SUPPORTED) {
+	if (NEON_PMULL_CPU_SUPPORTED)
 		rte_net_crc_neon_init();
-		return 1;
-	}
 #endif
-	return 0;
+}
+
+/* Default handling */
+
+static uint32_t
+rte_crc16_ccitt_default_handler(const uint8_t *data, uint32_t data_len)
+{
+	handlers = NULL;
+	if (max_simd_bitwidth == 0)
+		max_simd_bitwidth = rte_get_max_simd_bitwidth();
+
+	handlers = avx512_vpclmulqdq_get_handlers();
+	if (handlers != NULL)
+		return handlers[RTE_NET_CRC16_CCITT](data, data_len);
+	handlers = sse42_pclmulqdq_get_handlers();
+	if (handlers != NULL)
+		return handlers[RTE_NET_CRC16_CCITT](data, data_len);
+	handlers = neon_pmull_get_handlers();
+	if (handlers != NULL)
+		return handlers[RTE_NET_CRC16_CCITT](data, data_len);
+	handlers = handlers_scalar;
+	return handlers[RTE_NET_CRC16_CCITT](data, data_len);
+}
+
+static uint32_t
+rte_crc32_eth_default_handler(const uint8_t *data, uint32_t data_len)
+{
+	handlers = NULL;
+	if (max_simd_bitwidth == 0)
+		max_simd_bitwidth = rte_get_max_simd_bitwidth();
+
+	handlers = avx512_vpclmulqdq_get_handlers();
+	if (handlers != NULL)
+		return handlers[RTE_NET_CRC32_ETH](data, data_len);
+	handlers = sse42_pclmulqdq_get_handlers();
+	if (handlers != NULL)
+		return handlers[RTE_NET_CRC32_ETH](data, data_len);
+	handlers = neon_pmull_get_handlers();
+	if (handlers != NULL)
+		return handlers[RTE_NET_CRC32_ETH](data, data_len);
+	handlers = handlers_scalar;
+	return handlers[RTE_NET_CRC32_ETH](data, data_len);
 }
 
 /* Public API */
@@ -233,6 +293,8 @@ void
 rte_net_crc_set_alg(enum rte_net_crc_alg alg)
 {
 	handlers = NULL;
+	if (max_simd_bitwidth == 0)
+		max_simd_bitwidth = rte_get_max_simd_bitwidth();
 
 	switch (alg) {
 	case RTE_NET_CRC_AVX512:
@@ -270,19 +332,11 @@ rte_net_crc_calc(const void *data,
 	return ret;
 }
 
-/* Select highest available crc algorithm as default one */
+/* Call initialisation helpers for all crc algorithm handlers */
 RTE_INIT(rte_net_crc_init)
 {
-	enum rte_net_crc_alg alg = RTE_NET_CRC_SCALAR;
-
 	rte_net_crc_scalar_init();
-
-	if (sse42_pclmulqdq_init())
-		alg = RTE_NET_CRC_SSE42;
-	if (avx512_vpclmulqdq_init())
-		alg = RTE_NET_CRC_AVX512;
-	if (neon_pmull_init())
-		alg = RTE_NET_CRC_NEON;
-
-	rte_net_crc_set_alg(alg);
+	sse42_pclmulqdq_init();
+	avx512_vpclmulqdq_init();
+	neon_pmull_init();
 }
-- 
2.22.0