[net-next 3/9] i40e: Fix attach VF to VM issue

[Jeff Kirsher]

From: Paweł Jabłoński <pawel.jablon...@intel.com>

Fix for "Resource temporarily unavailable" problem when virsh is
trying to attach a device to VM. When the VF driver is loaded on
host and virsh is trying to attach it to the VM and set a MAC
address, it ends with a race condition between i40e_reset_vf and
i40e_ndo_set_vf_mac functions. The bug is fixed by adding polling
in i40e_ndo_set_vf_mac function For when the VF is in Reset mode.

Signed-off-by: Paweł Jabłoński <pawel.jablon...@intel.com>
Tested-by: Andrew Bowers <andrewx.bow...@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirs...@intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c 
b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
index e23975c67417..520d86357c69 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
@@ -3741,6 +3741,7 @@ int i40e_ndo_set_vf_mac(struct net_device *netdev, int 
vf_id, u8 *mac)
        int ret = 0;
        struct hlist_node *h;
        int bkt;
+       u8 i;
 
        /* validate the request */
        if (vf_id >= pf->num_alloc_vfs) {
@@ -3752,6 +3753,16 @@ int i40e_ndo_set_vf_mac(struct net_device *netdev, int 
vf_id, u8 *mac)
 
        vf = &(pf->vf[vf_id]);
        vsi = pf->vsi[vf->lan_vsi_idx];
+
+       /* When the VF is resetting wait until it is done.
+        * It can take up to 200 milliseconds,
+        * but wait for up to 300 milliseconds to be safe.
+        */
+       for (i = 0; i < 15; i++) {
+               if (test_bit(I40E_VF_STATE_INIT, &vf->vf_states))
+                       break;
+               msleep(20);
+       }
        if (!test_bit(I40E_VF_STATE_INIT, &vf->vf_states)) {
                dev_err(&pf->pdev->dev, "VF %d still in reset. Try again.\n",
                        vf_id);
-- 
2.14.3