igb: Limit maximum frame Rx based on MTU

In order to support the use of build_skb going forward it will be necessary
to place a maximum limit on the amount of data we can receive when jumbo
frames is not enabled.  In order to do this I am adding a new upper limit
for receive based on the size of a 2K buffer minus padding.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 17 insertions, 4 deletions

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index e541cccaae1b..1bf31224dfac 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -4250,7 +4250,7 @@ static void igb_set_rx_mode(struct net_device *netdev)
         struct igb_adapter *adapter = netdev_priv(netdev);
         struct e1000_hw *hw = &adapter->hw;
         unsigned int vfn = adapter->vfs_allocated_count;
-        u32 rctl = 0, vmolr = 0;
+        u32 rctl = 0, vmolr = 0, rlpml = MAX_JUMBO_FRAME_SIZE;
         int count;
 
         /* Check for Promiscuous and All Multicast modes */
@@ -4308,6 +4308,14 @@ static void igb_set_rx_mode(struct net_device *netdev)
                                      E1000_RCTL_VFE);
         wr32(E1000_RCTL, rctl);
 
+#if (PAGE_SIZE < 8192)
+        if (!adapter->vfs_allocated_count) {
+                if (adapter->max_frame_size <= IGB_MAX_FRAME_BUILD_SKB)
+                        rlpml = IGB_MAX_FRAME_BUILD_SKB;
+        }
+#endif
+        wr32(E1000_RLPML, rlpml);
+
         /* In order to support SR-IOV and eventually VMDq it is necessary to set
          * the VMOLR to enable the appropriate modes.  Without this workaround
          * we will have issues with VLAN tag stripping not being done for frames
@@ -4322,12 +4330,17 @@ static void igb_set_rx_mode(struct net_device *netdev)
         vmolr |= rd32(E1000_VMOLR(vfn)) &
                  ~(E1000_VMOLR_ROPE | E1000_VMOLR_MPME | E1000_VMOLR_ROMPE);
 
-        /* enable Rx jumbo frames, no need for restriction */
+        /* enable Rx jumbo frames, restrict as needed to support build_skb */
         vmolr &= ~E1000_VMOLR_RLPML_MASK;
-        vmolr |= MAX_JUMBO_FRAME_SIZE | E1000_VMOLR_LPE;
+#if (PAGE_SIZE < 8192)
+        if (adapter->max_frame_size <= IGB_MAX_FRAME_BUILD_SKB)
+                vmolr |= IGB_MAX_FRAME_BUILD_SKB;
+        else
+#endif
+                vmolr |= MAX_JUMBO_FRAME_SIZE;
+        vmolr |= E1000_VMOLR_LPE;
 
         wr32(E1000_VMOLR(vfn), vmolr);
-        wr32(E1000_RLPML, MAX_JUMBO_FRAME_SIZE);
 
         igb_restore_vf_multicasts(adapter);
 }