[PATCH] virtio-net: Fix the interpretation of max_tx_vq

[Akihiko Odaki <akihiko.odaki@daynix.com>]

virtio-net uses the max_tx_vq field of struct virtio_net_rss_config to
determine the number of queue pairs and emits an error message saying
"Can't get queue_pairs". However, the field tells only about tx.

Examine the indirection table to determine the number of queues required
for rx, and correct the name of field in the error message, clarifying
its correct semantics.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 hw/net/virtio-net.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index de87cfadffe1..d9ab9e1eb74d 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1450,23 +1450,28 @@ static uint16_t virtio_net_handle_rss(VirtIONet *n,
         err_value = (uint32_t)s;
         goto error;
     }
-    for (i = 0; i < n->rss_data.indirections_len; ++i) {
-        uint16_t val = n->rss_data.indirections_table[i];
-        n->rss_data.indirections_table[i] = virtio_lduw_p(vdev, &val);
-    }
     offset += size_get;
     size_get = sizeof(temp);
     s = iov_to_buf(iov, iov_cnt, offset, &temp, size_get);
     if (s != size_get) {
-        err_msg = "Can't get queue_pairs";
+        err_msg = "Can't get max_tx_vq";
         err_value = (uint32_t)s;
         goto error;
     }
-    queue_pairs = do_rss ? virtio_lduw_p(vdev, &temp.us) : n->curr_queue_pairs;
-    if (queue_pairs == 0 || queue_pairs > n->max_queue_pairs) {
-        err_msg = "Invalid number of queue_pairs";
-        err_value = queue_pairs;
-        goto error;
+    if (do_rss) {
+        queue_pairs = virtio_lduw_p(vdev, &temp.us);
+        for (i = 0; i < n->rss_data.indirections_len; ++i) {
+            uint16_t val = n->rss_data.indirections_table[i];
+            n->rss_data.indirections_table[i] = virtio_lduw_p(vdev, &val);
+            queue_pairs = MAX(queue_pairs, n->rss_data.indirections_table[i]);
+        }
+        if (queue_pairs == 0 || queue_pairs > n->max_queue_pairs) {
+            err_msg = "Invalid number of queue_pairs";
+            err_value = queue_pairs;
+            goto error;
+        }
+    } else {
+        queue_pairs = n->curr_queue_pairs;
     }
     if (temp.b > VIRTIO_NET_RSS_MAX_KEY_SIZE) {
         err_msg = "Invalid key size";

---
base-commit: 825b96dbcee23d134b691fc75618b59c5f53da32
change-id: 20250321-vq-87aff4f531bf

Best regards,
-- 
Akihiko Odaki <akihiko.odaki@daynix.com>