hv_netvsc: Implement set_channels ethtool op

This enables the use of ethtool --set-channels devname combined N to
change the number of vRSS queues. Separate rx, tx, and other parameters
are not supported. The maximum is rsscap.num_recv_que. It passes the
given value to rndis_filter_device_add through the device_info->num_chn
field.

If the procedure fails, it attempts to recover to the prior state. If
the recovery fails, it logs an error and aborts.

Current num_chn is saved and restored when changing the MTU.

Signed-off-by: Andrew Schwartzmeyer <andschwa@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 21845202a52d66469f6949c90af49db1310618b8..f3b9d3eb753b3e48ac689d66314c6e629a651566 100644 (file)
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -770,6 +770,101 @@ static void netvsc_get_channels(struct net_device *net,
        }
 }
 
+static int netvsc_set_channels(struct net_device *net,
+                              struct ethtool_channels *channels)
+{
+       struct net_device_context *net_device_ctx = netdev_priv(net);
+       struct hv_device *dev = net_device_ctx->device_ctx;
+       struct netvsc_device *nvdev = hv_get_drvdata(dev);
+       struct netvsc_device_info device_info;
+       const u32 num_chn = nvdev->num_chn;
+       const u32 max_chn = min_t(u32, nvdev->max_chn, num_online_cpus());
+       int ret = 0;
+       bool recovering = false;
+
+       if (!nvdev || nvdev->destroy)
+               return -ENODEV;
+
+       if (nvdev->nvsp_version < NVSP_PROTOCOL_VERSION_5) {
+               pr_info("vRSS unsupported before NVSP Version 5\n");
+               return -EINVAL;
+       }
+
+       /* We do not support rx, tx, or other */
+       if (!channels ||
+           channels->rx_count ||
+           channels->tx_count ||
+           channels->other_count ||
+           (channels->combined_count < 1))
+               return -EINVAL;
+
+       if (channels->combined_count > max_chn) {
+               pr_info("combined channels too high, using %d\n", max_chn);
+               channels->combined_count = max_chn;
+       }
+
+       ret = netvsc_close(net);
+       if (ret)
+               goto out;
+
+ do_set:
+       nvdev->start_remove = true;
+       rndis_filter_device_remove(dev);
+
+       nvdev->num_chn = channels->combined_count;
+
+       net_device_ctx->device_ctx = dev;
+       hv_set_drvdata(dev, net);
+
+       memset(&device_info, 0, sizeof(device_info));
+       device_info.num_chn = nvdev->num_chn; /* passed to RNDIS */
+       device_info.ring_size = ring_size;
+       device_info.max_num_vrss_chns = max_num_vrss_chns;
+
+       ret = rndis_filter_device_add(dev, &device_info);
+       if (ret) {
+               if (recovering) {
+                       netdev_err(net, "unable to add netvsc device (ret %d)\n", ret);
+                       return ret;
+               }
+               goto recover;
+       }
+
+       nvdev = hv_get_drvdata(dev);
+
+       ret = netif_set_real_num_tx_queues(net, nvdev->num_chn);
+       if (ret) {
+               if (recovering) {
+                       netdev_err(net, "could not set tx queue count (ret %d)\n", ret);
+                       return ret;
+               }
+               goto recover;
+       }
+
+       ret = netif_set_real_num_rx_queues(net, nvdev->num_chn);
+       if (ret) {
+               if (recovering) {
+                       netdev_err(net, "could not set rx queue count (ret %d)\n", ret);
+                       return ret;
+               }
+               goto recover;
+       }
+
+ out:
+       netvsc_open(net);
+
+       return ret;
+
+ recover:
+       /* If the above failed, we attempt to recover through the same
+        * process but with the original number of channels.
+        */
+       netdev_err(net, "could not set channels, recovering\n");
+       recovering = true;
+       channels->combined_count = num_chn;
+       goto do_set;
+}
+
 static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 {
        struct net_device_context *ndevctx = netdev_priv(ndev);
@@ -802,6 +897,7 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 
        memset(&device_info, 0, sizeof(device_info));
        device_info.ring_size = ring_size;
+       device_info.num_chn = nvdev->num_chn;
        device_info.max_num_vrss_chns = max_num_vrss_chns;
        rndis_filter_device_add(hdev, &device_info);
 
@@ -891,6 +987,7 @@ static const struct ethtool_ops ethtool_ops = {
        .get_drvinfo    = netvsc_get_drvinfo,
        .get_link       = ethtool_op_get_link,
        .get_channels   = netvsc_get_channels,
+       .set_channels   = netvsc_set_channels,
 };
 
 static const struct net_device_ops device_ops = {