hv_netvsc: Fix ethtool change hash key error

Hyper-V hosts require us to disable RSS before changing RSS key,
otherwise the changing request will fail. This patch fixes the
coding error.

Fixes: ff4a4419 ("netvsc: allow get/set of RSS indirection table")
Reported-by: Wei Hu <weh@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
[sl: fix up subject line]
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/hyperv/rndis_filter.c

@@ -774,8 +774,8 @@ rndis_filter_set_offload_params(struct net_device *ndev,
 	return ret;
 }
 
-int rndis_filter_set_rss_param(struct rndis_device *rdev,
-			       const u8 *rss_key)
+static int rndis_set_rss_param_msg(struct rndis_device *rdev,
+				   const u8 *rss_key, u16 flag)
 {
 	struct net_device *ndev = rdev->ndev;
 	struct rndis_request *request;
@@ -804,7 +804,7 @@ int rndis_filter_set_rss_param(struct rndis_device *rdev,
 	rssp->hdr.type = NDIS_OBJECT_TYPE_RSS_PARAMETERS;
 	rssp->hdr.rev = NDIS_RECEIVE_SCALE_PARAMETERS_REVISION_2;
 	rssp->hdr.size = sizeof(struct ndis_recv_scale_param);
-	rssp->flag = 0;
+	rssp->flag = flag;
 	rssp->hashinfo = NDIS_HASH_FUNC_TOEPLITZ | NDIS_HASH_IPV4 |
 			 NDIS_HASH_TCP_IPV4 | NDIS_HASH_IPV6 |
 			 NDIS_HASH_TCP_IPV6;
@@ -829,9 +829,12 @@ int rndis_filter_set_rss_param(struct rndis_device *rdev,
 
 	wait_for_completion(&request->wait_event);
 	set_complete = &request->response_msg.msg.set_complete;
-	if (set_complete->status == RNDIS_STATUS_SUCCESS)
-		memcpy(rdev->rss_key, rss_key, NETVSC_HASH_KEYLEN);
-	else {
+	if (set_complete->status == RNDIS_STATUS_SUCCESS) {
+		if (!(flag & NDIS_RSS_PARAM_FLAG_DISABLE_RSS) &&
+		    !(flag & NDIS_RSS_PARAM_FLAG_HASH_KEY_UNCHANGED))
+			memcpy(rdev->rss_key, rss_key, NETVSC_HASH_KEYLEN);
+
+	} else {
 		netdev_err(ndev, "Fail to set RSS parameters:0x%x\n",
 			   set_complete->status);
 		ret = -EINVAL;
@@ -842,6 +845,16 @@ int rndis_filter_set_rss_param(struct rndis_device *rdev,
 	return ret;
 }
 
+int rndis_filter_set_rss_param(struct rndis_device *rdev,
+			       const u8 *rss_key)
+{
+	/* Disable RSS before change */
+	rndis_set_rss_param_msg(rdev, rss_key,
+				NDIS_RSS_PARAM_FLAG_DISABLE_RSS);
+
+	return rndis_set_rss_param_msg(rdev, rss_key, 0);
+}
+
 static int rndis_filter_query_device_link_status(struct rndis_device *dev,
 						 struct netvsc_device *net_device)
 {