patch 'net/iavf: remove incorrect 16B descriptor read block' has been queued to stable release 22.11.5

[luca.boccassi at gmail.com]

Hi,

FYI, your patch has been queued to stable release 22.11.5

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 03/16/24. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/bluca/dpdk-stable

This queued commit can be viewed at:
https://github.com/bluca/dpdk-stable/commit/0d2f5b4ca1273de6110a936d5418f766f965d6ce

Thanks.

Luca Boccassi

---
>From 0d2f5b4ca1273de6110a936d5418f766f965d6ce Mon Sep 17 00:00:00 2001
From: Bruce Richardson <bruce.richardson at intel.com>
Date: Tue, 23 Jan 2024 11:40:50 +0000
Subject: [PATCH] net/iavf: remove incorrect 16B descriptor read block

[ upstream commit d4ade5d02d188fcbe51871c5a5d66ef075ca0f86 ]

By default, the driver works with 32B descriptors, but has a separate
descriptor read block for reading two descriptors at a time when using
16B descriptors. However, the 32B reads used are not guaranteed to be
atomic, which will cause issues if that is not the case on a system,
since the descriptors may be read in an undefined order.  Remove the
block, to avoid issues, and just use the regular descriptor reading path
for 16B descriptors, if that support is enabled at build time.

Fixes: af0c246a3800 ("net/iavf: enable AVX2 for iavf")

Signed-off-by: Bruce Richardson <bruce.richardson at intel.com>
Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>
---
 drivers/net/iavf/iavf_rxtx_vec_avx2.c | 78 ++++++++-------------------
 1 file changed, 23 insertions(+), 55 deletions(-)

diff --git a/drivers/net/iavf/iavf_rxtx_vec_avx2.c b/drivers/net/iavf/iavf_rxtx_vec_avx2.c
index b4ebac9d34..7bf22d5c0d 100644
--- a/drivers/net/iavf/iavf_rxtx_vec_avx2.c
+++ b/drivers/net/iavf/iavf_rxtx_vec_avx2.c
@@ -192,62 +192,30 @@ _iavf_recv_raw_pkts_vec_avx2(struct iavf_rx_queue *rxq,
 			 _mm256_loadu_si256((void *)&sw_ring[i + 4]));
 #endif
 
-		__m256i raw_desc0_1, raw_desc2_3, raw_desc4_5, raw_desc6_7;
-#ifdef RTE_LIBRTE_IAVF_16BYTE_RX_DESC
-		/* for AVX we need alignment otherwise loads are not atomic */
-		if (avx_aligned) {
-			/* load in descriptors, 2 at a time, in reverse order */
-			raw_desc6_7 = _mm256_load_si256((void *)(rxdp + 6));
-			rte_compiler_barrier();
-			raw_desc4_5 = _mm256_load_si256((void *)(rxdp + 4));
-			rte_compiler_barrier();
-			raw_desc2_3 = _mm256_load_si256((void *)(rxdp + 2));
-			rte_compiler_barrier();
-			raw_desc0_1 = _mm256_load_si256((void *)(rxdp + 0));
-		} else
-#endif
-		{
-			const __m128i raw_desc7 =
-				_mm_load_si128((void *)(rxdp + 7));
-			rte_compiler_barrier();
-			const __m128i raw_desc6 =
-				_mm_load_si128((void *)(rxdp + 6));
-			rte_compiler_barrier();
-			const __m128i raw_desc5 =
-				_mm_load_si128((void *)(rxdp + 5));
-			rte_compiler_barrier();
-			const __m128i raw_desc4 =
-				_mm_load_si128((void *)(rxdp + 4));
-			rte_compiler_barrier();
-			const __m128i raw_desc3 =
-				_mm_load_si128((void *)(rxdp + 3));
-			rte_compiler_barrier();
-			const __m128i raw_desc2 =
-				_mm_load_si128((void *)(rxdp + 2));
-			rte_compiler_barrier();
-			const __m128i raw_desc1 =
-				_mm_load_si128((void *)(rxdp + 1));
-			rte_compiler_barrier();
-			const __m128i raw_desc0 =
-				_mm_load_si128((void *)(rxdp + 0));
+		const __m128i raw_desc7 = _mm_load_si128((void *)(rxdp + 7));
+		rte_compiler_barrier();
+		const __m128i raw_desc6 = _mm_load_si128((void *)(rxdp + 6));
+		rte_compiler_barrier();
+		const __m128i raw_desc5 = _mm_load_si128((void *)(rxdp + 5));
+		rte_compiler_barrier();
+		const __m128i raw_desc4 = _mm_load_si128((void *)(rxdp + 4));
+		rte_compiler_barrier();
+		const __m128i raw_desc3 = _mm_load_si128((void *)(rxdp + 3));
+		rte_compiler_barrier();
+		const __m128i raw_desc2 = _mm_load_si128((void *)(rxdp + 2));
+		rte_compiler_barrier();
+		const __m128i raw_desc1 = _mm_load_si128((void *)(rxdp + 1));
+		rte_compiler_barrier();
+		const __m128i raw_desc0 = _mm_load_si128((void *)(rxdp + 0));
 
-			raw_desc6_7 =
-				_mm256_inserti128_si256
-					(_mm256_castsi128_si256(raw_desc6),
-					 raw_desc7, 1);
-			raw_desc4_5 =
-				_mm256_inserti128_si256
-					(_mm256_castsi128_si256(raw_desc4),
-					 raw_desc5, 1);
-			raw_desc2_3 =
-				_mm256_inserti128_si256
-					(_mm256_castsi128_si256(raw_desc2),
-					 raw_desc3, 1);
-			raw_desc0_1 =
-				_mm256_inserti128_si256
-					(_mm256_castsi128_si256(raw_desc0),
-					 raw_desc1, 1);
-		}
+		const __m256i raw_desc6_7 =
+			_mm256_inserti128_si256(_mm256_castsi128_si256(raw_desc6), raw_desc7, 1);
+		const __m256i raw_desc4_5 =
+			_mm256_inserti128_si256(_mm256_castsi128_si256(raw_desc4), raw_desc5, 1);
+		const __m256i raw_desc2_3 =
+			_mm256_inserti128_si256(_mm256_castsi128_si256(raw_desc2), raw_desc3, 1);
+		const __m256i raw_desc0_1 =
+			_mm256_inserti128_si256(_mm256_castsi128_si256(raw_desc0), raw_desc1, 1);
 
 		if (split_packet) {
 			int j;
-- 
2.39.2

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2024-03-14 00:09:21.850972499 +0000
+++ 0024-net-iavf-remove-incorrect-16B-descriptor-read-block.patch	2024-03-14 00:09:20.601614983 +0000
@@ -1 +1 @@
-From d4ade5d02d188fcbe51871c5a5d66ef075ca0f86 Mon Sep 17 00:00:00 2001
+From 0d2f5b4ca1273de6110a936d5418f766f965d6ce Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit d4ade5d02d188fcbe51871c5a5d66ef075ca0f86 ]
+
@@ -15 +16,0 @@
-Cc: stable at dpdk.org
@@ -24 +25 @@
-index 510b4d8f1c..49d41af953 100644
+index b4ebac9d34..7bf22d5c0d 100644
@@ -27 +28 @@
-@@ -193,62 +193,30 @@ _iavf_recv_raw_pkts_vec_avx2(struct iavf_rx_queue *rxq,
+@@ -192,62 +192,30 @@ _iavf_recv_raw_pkts_vec_avx2(struct iavf_rx_queue *rxq,