ethtool: Add support for control of RX flow hash indirection

Many NICs use an indirection table to map an RX flow hash value to one
of an arbitrary number of queues (not necessarily a power of 2).  It
can be useful to remove some queues from this indirection table so
that they are only used for flows that are specifically filtered
there.  It may also be useful to weight the mapping to account for
user processes with the same CPU-affinity as the RX interrupts.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 80 insertions, 0 deletions

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 5d42fae520d9..072d1d3796cb 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -358,6 +358,80 @@ err_out:
         return ret;
 }
 
+static noinline_for_stack int ethtool_get_rxfh_indir(struct net_device *dev,
+                                                     void __user *useraddr)
+{
+        struct ethtool_rxfh_indir *indir;
+        u32 table_size;
+        size_t full_size;
+        int ret;
+
+        if (!dev->ethtool_ops->get_rxfh_indir)
+                return -EOPNOTSUPP;
+
+        if (copy_from_user(&table_size,
+                           useraddr + offsetof(struct ethtool_rxfh_indir, size),
+                           sizeof(table_size)))
+                return -EFAULT;
+
+        if (table_size >
+            (KMALLOC_MAX_SIZE - sizeof(*indir)) / sizeof(*indir->ring_index))
+                return -ENOMEM;
+        full_size = sizeof(*indir) + sizeof(*indir->ring_index) * table_size;
+        indir = kmalloc(full_size, GFP_USER);
+        if (!indir)
+                return -ENOMEM;
+
+        indir->cmd = ETHTOOL_GRXFHINDIR;
+        indir->size = table_size;
+        ret = dev->ethtool_ops->get_rxfh_indir(dev, indir);
+        if (ret)
+                goto out;
+
+        if (copy_to_user(useraddr, indir, full_size))
+                ret = -EFAULT;
+
+out:
+        kfree(indir);
+        return ret;
+}
+
+static noinline_for_stack int ethtool_set_rxfh_indir(struct net_device *dev,
+                                                     void __user *useraddr)
+{
+        struct ethtool_rxfh_indir *indir;
+        u32 table_size;
+        size_t full_size;
+        int ret;
+
+        if (!dev->ethtool_ops->set_rxfh_indir)
+                return -EOPNOTSUPP;
+
+        if (copy_from_user(&table_size,
+                           useraddr + offsetof(struct ethtool_rxfh_indir, size),
+                           sizeof(table_size)))
+                return -EFAULT;
+
+        if (table_size >
+            (KMALLOC_MAX_SIZE - sizeof(*indir)) / sizeof(*indir->ring_index))
+                return -ENOMEM;
+        full_size = sizeof(*indir) + sizeof(*indir->ring_index) * table_size;
+        indir = kmalloc(full_size, GFP_USER);
+        if (!indir)
+                return -ENOMEM;
+
+        if (copy_from_user(indir, useraddr, full_size)) {
+                ret = -EFAULT;
+                goto out;
+        }
+
+        ret = dev->ethtool_ops->set_rxfh_indir(dev, indir);
+
+out:
+        kfree(indir);
+        return ret;
+}
+
 static void __rx_ntuple_filter_add(struct ethtool_rx_ntuple_list *list,
                         struct ethtool_rx_ntuple_flow_spec *spec,
                         struct ethtool_rx_ntuple_flow_spec_container *fsc)
@@ -1526,6 +1600,12 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
         case ETHTOOL_GSSET_INFO:
                 rc = ethtool_get_sset_info(dev, useraddr);
                 break;
+        case ETHTOOL_GRXFHINDIR:
+                rc = ethtool_get_rxfh_indir(dev, useraddr);
+                break;
+        case ETHTOOL_SRXFHINDIR:
+                rc = ethtool_set_rxfh_indir(dev, useraddr);
+                break;
         default:
                 rc = -EOPNOTSUPP;
         }