linux-kernel - [PATCH vhost v3 20/24] vdpa/mlx5: Use suspend/resume during VQP change

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Message-ID: <20240708-stage-vdpa-vq-precreate-v3-20-afe3c766e393@nvidia.com>
Date: Mon, 8 Jul 2024 15:00:44 +0300
From: Dragos Tatulea <dtatulea@...dia.com>
To: "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Eugenio Pérez
	<eperezma@...hat.com>, Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky
	<leon@...nel.org>, Tariq Toukan <tariqt@...dia.com>, Si-Wei Liu
	<si-wei.liu@...cle.com>
CC: <virtualization@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
	<linux-rdma@...r.kernel.org>, <netdev@...r.kernel.org>, Cosmin Ratiu
	<cratiu@...dia.com>, Dragos Tatulea <dtatulea@...dia.com>
Subject: [PATCH vhost v3 20/24] vdpa/mlx5: Use suspend/resume during VQP
 change

Resume a VQ if it is already created when the number of VQ pairs
increases. This is done in preparation for VQ pre-creation which is
coming in a later patch. It is necessary because calling setup_vq() on
an already created VQ will return early and will not enable the queue.

For symmetry, suspend a VQ instead of tearing it down when the number of
VQ pairs decreases. But only if the resume operation is supported.

Reviewed-by: Cosmin Ratiu <cratiu@...dia.com>
Acked-by: Eugenio Pérez <eperezma@...hat.com>
Signed-off-by: Dragos Tatulea <dtatulea@...dia.com>
---
 drivers/vdpa/mlx5/net/mlx5_vnet.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index ce1f6a1f36cd..324604b16b91 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -2130,14 +2130,22 @@ static int change_num_qps(struct mlx5_vdpa_dev *mvdev, int newqps)
 		if (err)
 			return err;
 
-		for (i = ndev->cur_num_vqs - 1; i >= 2 * newqps; i--)
-			teardown_vq(ndev, &ndev->vqs[i]);
+		for (i = ndev->cur_num_vqs - 1; i >= 2 * newqps; i--) {
+			struct mlx5_vdpa_virtqueue *mvq = &ndev->vqs[i];
+
+			if (is_resumable(ndev))
+				suspend_vq(ndev, mvq);
+			else
+				teardown_vq(ndev, mvq);
+		}
 
 		ndev->cur_num_vqs = 2 * newqps;
 	} else {
 		ndev->cur_num_vqs = 2 * newqps;
 		for (i = cur_qps * 2; i < 2 * newqps; i++) {
-			err = setup_vq(ndev, &ndev->vqs[i], true);
+			struct mlx5_vdpa_virtqueue *mvq = &ndev->vqs[i];
+
+			err = mvq->initialized ? resume_vq(ndev, mvq) : setup_vq(ndev, mvq, true);
 			if (err)
 				goto clean_added;
 		}

-- 
2.45.2