ixgbe: Force QDE via PFQDE for VFs during reset

This change makes it so that the QDE bits are set for a VF before the Rx
queues are enabled.  As such we avoid head of line blocking in the event
that the VF stops cleaning Rx descriptors for whatever reason.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>

 drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c |   14 ++++++++++++++
 drivers/net/ethernet/intel/ixgbe/ixgbe_type.h  |    7 ++++---
 2 files changed, 18 insertions(+), 3 deletions(-)
Signed-off-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c

@@ -631,11 +631,14 @@ int ixgbe_vf_configuration(struct pci_dev *pdev, unsigned int event_mask)
 
 static int ixgbe_vf_reset_msg(struct ixgbe_adapter *adapter, u32 vf)
 {
+	struct ixgbe_ring_feature *vmdq = &adapter->ring_feature[RING_F_VMDQ];
 	struct ixgbe_hw *hw = &adapter->hw;
 	unsigned char *vf_mac = adapter->vfinfo[vf].vf_mac_addresses;
 	u32 reg, reg_offset, vf_shift;
 	u32 msgbuf[4] = {0, 0, 0, 0};
 	u8 *addr = (u8 *)(&msgbuf[1]);
+	u32 q_per_pool = __ALIGN_MASK(1, ~vmdq->mask);
+	int i;
 
 	e_info(probe, "VF Reset msg received from vf %d\n", vf);
 
@@ -654,6 +657,17 @@ static int ixgbe_vf_reset_msg(struct ixgbe_adapter *adapter, u32 vf)
 	reg |= 1 << vf_shift;
 	IXGBE_WRITE_REG(hw, IXGBE_VFTE(reg_offset), reg);
 
+	/* force drop enable for all VF Rx queues */
+	for (i = vf * q_per_pool; i < ((vf + 1) * q_per_pool); i++) {
+		/* flush previous write */
+		IXGBE_WRITE_FLUSH(hw);
+
+		/* indicate to hardware that we want to set drop enable */
+		reg = IXGBE_QDE_WRITE | IXGBE_QDE_ENABLE;
+		reg |= i <<  IXGBE_QDE_IDX_SHIFT;
+		IXGBE_WRITE_REG(hw, IXGBE_QDE, reg);
+	}
+
 	/* enable receive for vf */
 	reg = IXGBE_READ_REG(hw, IXGBE_VFRE(reg_offset));
 	reg |= 1 << vf_shift;

drivers/net/ethernet/intel/ixgbe/ixgbe_type.h

@@ -1980,9 +1980,10 @@ enum {
 #define IXGBE_FWSM_TS_ENABLED	0x1
 
 /* Queue Drop Enable */
-#define IXGBE_QDE_ENABLE     0x00000001
-#define IXGBE_QDE_IDX_MASK   0x00007F00
-#define IXGBE_QDE_IDX_SHIFT           8
+#define IXGBE_QDE_ENABLE	0x00000001
+#define IXGBE_QDE_IDX_MASK	0x00007F00
+#define IXGBE_QDE_IDX_SHIFT	8
+#define IXGBE_QDE_WRITE		0x00010000
 
 #define IXGBE_TXD_POPTS_IXSM 0x01       /* Insert IP checksum */
 #define IXGBE_TXD_POPTS_TXSM 0x02       /* Insert TCP/UDP checksum */