Re: [dpdk-dev] [PATCH v6 4/7] vhost: fix NUMA reallocation with multiqueue

-----Original Message-----
From: Maxime Coquelin <redacted>
Sent: Friday, June 18, 2021 10:04 PM
To: dev@dpdk.org; david.marchand@redhat.com; Xia, Chenbo <redacted>
Cc: Maxime Coquelin <redacted>; stable@dpdk.org
Subject: [PATCH v6 4/7] vhost: fix NUMA reallocation with multiqueue

Since the Vhost-user device initialization has been reworked,
enabling the application to start using the device as soon as
the first queue pair is ready, NUMA reallocation no more
happened on queue pairs other than the first one since
numa_realloc() was returning early if the device was running.

This patch fixes this issue by only preventing the device
metadata to be allocated if the device is running. For the
virtqueues, a vring state change notification is sent to
notify the application of its disablement. Since the callback
is supposed to be blocking, it is safe to reallocate it
afterwards.

Fixes: d0fcc38f5fa4 ("vhost: improve device readiness notifications")
Cc: stable@dpdk.org

Signed-off-by: Maxime Coquelin <redacted>
---
 lib/vhost/vhost_user.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index 82adf80fe5..51b96a0716 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c

@@ -488,12 +488,16 @@ numa_realloc(struct virtio_net *dev, int index)
 	struct batch_copy_elem *new_batch_copy_elems;
 	int ret;

-	if (dev->flags & VIRTIO_DEV_RUNNING)
-		return dev;
-
 	old_dev = dev;
 	vq = old_vq = dev->virtqueue[index];

+	/*
+	 * If VQ is ready, it is too late to reallocate, it certainly already
+	 * happened anyway on VHOST_USER_SET_VRING_ADRR.
+	 */
+	if (vq->ready)
+		return dev;
+
 	ret = get_mempolicy(&newnode, NULL, 0, old_vq->desc,
 			    MPOL_F_NODE | MPOL_F_ADDR);

@@ -558,6 +562,9 @@ numa_realloc(struct virtio_net *dev, int index)
 		rte_free(old_vq);
 	}

+	if (dev->flags & VIRTIO_DEV_RUNNING)
+		goto out;
+