[dpdk-dev] [PATCH v2] net/virtio: fix AVX512 datapath selection

[Ferruh Yigit <ferruh.yigit@intel.com>]

From: Maxime Coquelin <maxime.coquelin@redhat.com>

The AVX512 packed ring datapath selection was only done
at build time, but it should also be checked at runtime
that the CPU supports it.

This patch add a CPU flags check so that non-vectorized
path is selected at runtime if AVX512 is not supported.

Also in meson build enable vectorization only for relevant file, not for
all driver.

Fixes: ccb10995c2ad ("net/virtio: add election for vectorized path")

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
---
Cc: Bruce Richardson <bruce.richardson@intel.com>
Cc: Radu Nicolau <radu.nicolau@intel.com>
Cc: Luca Boccassi <bluca@debian.org>

For meson I mainly adapted implementation from other driver, not able to
test or verify myself.
---
 drivers/net/virtio/meson.build     | 9 +++++++--
 drivers/net/virtio/virtio_ethdev.c | 6 ++++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio/meson.build b/drivers/net/virtio/meson.build
index 5cc529f6aa..3fd6051f4b 100644
--- a/drivers/net/virtio/meson.build
+++ b/drivers/net/virtio/meson.build
@@ -11,8 +11,14 @@ deps += ['kvargs', 'bus_pci']
 if arch_subdir == 'x86'
 	if not machine_args.contains('-mno-avx512f')
 		if cc.has_argument('-mavx512f') and cc.has_argument('-mavx512vl') and cc.has_argument('-mavx512bw')
-			cflags += ['-mavx512f', '-mavx512bw', '-mavx512vl']
 			cflags += ['-DCC_AVX512_SUPPORT']
+			virtio_avx512_lib = static_library('virtio_avx512_lib',
+					      'virtio_rxtx_packed_avx.c',
+					      dependencies: [static_rte_ethdev,
+						static_rte_kvargs, static_rte_bus_pci],
+					      include_directories: includes,
+					      c_args: [cflags, '-mavx512f', '-mavx512bw', '-mavx512vl'])
+			objs += virtio_avx512_lib.extract_objects('virtio_rxtx_packed_avx.c')
 			if (toolchain == 'gcc' and cc.version().version_compare('>=8.3.0'))
 				cflags += '-DVHOST_GCC_UNROLL_PRAGMA'
 			elif (toolchain == 'clang' and cc.version().version_compare('>=3.7.0'))
@@ -20,7 +26,6 @@ if arch_subdir == 'x86'
 			elif (toolchain == 'icc' and cc.version().version_compare('>=16.0.0'))
 				cflags += '-DVHOST_ICC_UNROLL_PRAGMA'
 			endif
-			sources += files('virtio_rxtx_packed_avx.c')
 		endif
 	endif
 	sources += files('virtio_rxtx_simple_sse.c')
diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 312871cb48..49ccef12c7 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -1965,8 +1965,10 @@ eth_virtio_dev_init(struct rte_eth_dev *eth_dev)
 			PMD_DRV_LOG(INFO,
 				"building environment do not support packed ring vectorized");
 #else
-			hw->use_vec_rx = 1;
-			hw->use_vec_tx = 1;
+			if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_AVX512F)) {
+				hw->use_vec_rx = 1;
+				hw->use_vec_tx = 1;
+			}
 #endif
 		}
 	}
-- 
2.25.4