[PATCH net 1/4] virtio_net: Support dynamic rss indirection table size

[Philo Lu]

When reading/writing virtio_net_ctrl_rss, we get the indirection table
size from vi->rss_indir_table_size, which is initialized in
virtnet_probe(). However, the actual size of indirection_table was set
as VIRTIO_NET_RSS_MAX_TABLE_LEN=128. This collision may cause issues if
the vi->rss_indir_table_size exceeds 128.

This patch instead uses dynamic indirection table, allocated with
vi->rss after vi->rss_indir_table_size initialized. And free it in
virtnet_remove().

In virtnet_commit_rss_command(), sgs for rss is initialized differently
with hash_report. So indirection_table is not used if !vi->has_rss, and
then we don't need to alloc indirection_table for hash_report only uses.

Fixes: c7114b1249fa ("drivers/net/virtio_net: Added basic RSS support.")
Signed-off-by: Philo Lu <lulie@xxxxxxxxxxxxxxxxx>
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
 drivers/net/virtio_net.c | 39 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 34 insertions(+), 5 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 869586c17ffd..75c1ff4efd13 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -368,15 +368,16 @@ struct receive_queue {
  * because table sizes may be differ according to the device configuration.
  */
 #define VIRTIO_NET_RSS_MAX_KEY_SIZE     40
-#define VIRTIO_NET_RSS_MAX_TABLE_LEN    128
 struct virtio_net_ctrl_rss {
 	u32 hash_types;
 	u16 indirection_table_mask;
 	u16 unclassified_queue;
-	u16 indirection_table[VIRTIO_NET_RSS_MAX_TABLE_LEN];
+	u16 hash_cfg_reserved; /* for HASH_CONFIG (see virtio_net_hash_config for details) */
 	u16 max_tx_vq;
 	u8 hash_key_length;
 	u8 key[VIRTIO_NET_RSS_MAX_KEY_SIZE];
+
+	u16 *indirection_table;
 };
 
 /* Control VQ buffers: protected by the rtnl lock */
@@ -512,6 +513,25 @@ static struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
 					       struct page *page, void *buf,
 					       int len, int truesize);
 
+static int rss_indirection_table_alloc(struct virtio_net_ctrl_rss *rss, u16 indir_table_size)
+{
+	if (!indir_table_size) {
+		rss->indirection_table = NULL;
+		return 0;
+	}
+
+	rss->indirection_table = kmalloc_array(indir_table_size, sizeof(u16), GFP_KERNEL);
+	if (!rss->indirection_table)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void rss_indirection_table_free(struct virtio_net_ctrl_rss *rss)
+{
+	kfree(rss->indirection_table);
+}
+
 static bool is_xdp_frame(void *ptr)
 {
 	return (unsigned long)ptr & VIRTIO_XDP_FLAG;
@@ -3828,11 +3848,15 @@ static bool virtnet_commit_rss_command(struct virtnet_info *vi)
 	/* prepare sgs */
 	sg_init_table(sgs, 4);
 
-	sg_buf_size = offsetof(struct virtio_net_ctrl_rss, indirection_table);
+	sg_buf_size = offsetof(struct virtio_net_ctrl_rss, hash_cfg_reserved);
 	sg_set_buf(&sgs[0], &vi->rss, sg_buf_size);
 
-	sg_buf_size = sizeof(uint16_t) * (vi->rss.indirection_table_mask + 1);
-	sg_set_buf(&sgs[1], vi->rss.indirection_table, sg_buf_size);
+	if (vi->has_rss) {
+		sg_buf_size = sizeof(uint16_t) * vi->rss_indir_table_size;
+		sg_set_buf(&sgs[1], vi->rss.indirection_table, sg_buf_size);
+	} else {
+		sg_set_buf(&sgs[1], &vi->rss.hash_cfg_reserved, sizeof(uint16_t));
+	}
 
 	sg_buf_size = offsetof(struct virtio_net_ctrl_rss, key)
 			- offsetof(struct virtio_net_ctrl_rss, max_tx_vq);
@@ -6420,6 +6444,9 @@ static int virtnet_probe(struct virtio_device *vdev)
 			virtio_cread16(vdev, offsetof(struct virtio_net_config,
 				rss_max_indirection_table_length));
 	}
+	err = rss_indirection_table_alloc(&vi->rss, vi->rss_indir_table_size);
+	if (err)
+		goto free;
 
 	if (vi->has_rss || vi->has_rss_hash_report) {
 		vi->rss_key_size =
@@ -6674,6 +6701,8 @@ static void virtnet_remove(struct virtio_device *vdev)
 
 	remove_vq_common(vi);
 
+	rss_indirection_table_free(&vi->rss);
+
 	free_netdev(vi->dev);
 }
 
-- 
2.32.0.3.g01195cf9f