[dpdk-stable] patch 'vdpa/mlx5: workaround FW first completion in start' has been queued to stable release 20.11.4

[Xueming Li]

Hi,

FYI, your patch has been queued to stable release 20.11.4

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 11/12/21. 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/steevenlee/dpdk

This queued commit can be viewed at:
https://github.com/steevenlee/dpdk/commit/e1fe4bd76ff38a3b95dc5357b8675b4cdcb0f865

Thanks.

Xueming Li <xuemingl at nvidia.com>

---
>From e1fe4bd76ff38a3b95dc5357b8675b4cdcb0f865 Mon Sep 17 00:00:00 2001
From: Xueming Li <xuemingl at nvidia.com>
Date: Fri, 15 Oct 2021 23:05:44 +0800
Subject: [PATCH] vdpa/mlx5: workaround FW first completion in start
Cc: Xueming Li <xuemingl at nvidia.com>

[ upstream commit d38a53b175935066b7a7a9c1d632c5f92cea7f5d ]

After a vDPA application restart, Qemu restores VQ with used and
available index, new incoming packet triggers virtio driver to
handle buffers. Under heavy traffic, no available buffer for
firmware to receive new packets, no Rx interrupts generated,
driver is stuck on endless interrupt waiting.

As a firmware workaround, this patch sends a notification after
VQ setup to ask driver handling buffers and filling new buffers.

Fixes: bff735011078 ("vdpa/mlx5: prepare virtio queues")

Signed-off-by: Xueming Li <xuemingl at nvidia.com>
Reviewed-by: Matan Azrad <matan at nvidia.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 drivers/vdpa/mlx5/mlx5_vdpa_virtq.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c b/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c
index 472bda6c23..24a8705e24 100644
--- a/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c
+++ b/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c
@@ -4,6 +4,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <sys/mman.h>
+#include <sys/eventfd.h>
 
 #include <rte_malloc.h>
 #include <rte_errno.h>
@@ -364,6 +365,9 @@ mlx5_vdpa_virtq_setup(struct mlx5_vdpa_priv *priv, int index)
 		goto error;
 	}
 	virtq->stopped = false;
+	/* Initial notification to ask Qemu handling completed buffers. */
+	if (virtq->eqp.cq.callfd != -1)
+		eventfd_write(virtq->eqp.cq.callfd, (eventfd_t)1);
 	DRV_LOG(DEBUG, "vid %u virtq %u was created successfully.", priv->vid,
 		index);
 	return 0;
-- 
2.33.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2021-11-10 14:17:09.838684968 +0800
+++ 0178-vdpa-mlx5-workaround-FW-first-completion-in-start.patch	2021-11-10 14:17:01.990745109 +0800
@@ -1 +1 @@
-From d38a53b175935066b7a7a9c1d632c5f92cea7f5d Mon Sep 17 00:00:00 2001
+From e1fe4bd76ff38a3b95dc5357b8675b4cdcb0f865 Mon Sep 17 00:00:00 2001
@@ -4,0 +5,3 @@
+Cc: Xueming Li <xuemingl at nvidia.com>
+
+[ upstream commit d38a53b175935066b7a7a9c1d632c5f92cea7f5d ]
@@ -16 +18,0 @@
-Cc: stable at dpdk.org
@@ -26 +28 @@
-index cfd50d92f5..c5b357a83b 100644
+index 472bda6c23..24a8705e24 100644
@@ -37 +39 @@
-@@ -367,6 +368,9 @@ mlx5_vdpa_virtq_setup(struct mlx5_vdpa_priv *priv, int index)
+@@ -364,6 +365,9 @@ mlx5_vdpa_virtq_setup(struct mlx5_vdpa_priv *priv, int index)