[PATCH v3] igb: Allocate MSI-X vector when testing

[Akihiko Odaki]

Without this change, the interrupt test fail with MSI-X environment:

$ sudo ethtool -t enp0s2 offline
[   43.921783] igb 0000:00:02.0: offline testing starting
[   44.855824] igb 0000:00:02.0 enp0s2: igb: enp0s2 NIC Link is Down
[   44.961249] igb 0000:00:02.0 enp0s2: igb: enp0s2 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
[   51.272202] igb 0000:00:02.0: testing shared interrupt
[   56.996975] igb 0000:00:02.0 enp0s2: igb: enp0s2 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
The test result is FAIL
The test extra info:
Register test  (offline)	 0
Eeprom test    (offline)	 0
Interrupt test (offline)	 4
Loopback test  (offline)	 0
Link test   (on/offline)	 0

Here, "4" means an expected interrupt was not delivered.

To fix this, route IRQs correctly to the first MSI-X vector by setting
IVAR_MISC. Also, set bit 0 of EIMS so that the vector will not be
masked. The interrupt test now runs properly with this change:

$ sudo ethtool -t enp0s2 offline
[   42.762985] igb 0000:00:02.0: offline testing starting
[   50.141967] igb 0000:00:02.0: testing shared interrupt
[   56.163957] igb 0000:00:02.0 enp0s2: igb: enp0s2 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
The test result is PASS
The test extra info:
Register test  (offline)	 0
Eeprom test    (offline)	 0
Interrupt test (offline)	 0
Loopback test  (offline)	 0
Link test   (on/offline)	 0

Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>
---
 drivers/net/ethernet/intel/igb/igb_ethtool.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/intel/igb/igb_ethtool.c b/drivers/net/ethernet/intel/igb/igb_ethtool.c
index e5f3e7680dc6..ff911af16a4b 100644
--- a/drivers/net/ethernet/intel/igb/igb_ethtool.c
+++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c
@@ -1413,6 +1413,8 @@ static int igb_intr_test(struct igb_adapter *adapter, u64 *data)
 			*data = 1;
 			return -1;
 		}
+		wr32(E1000_IVAR_MISC, E1000_IVAR_VALID << 8);
+		wr32(E1000_EIMS, BIT(0));
 	} else if (adapter->flags & IGB_FLAG_HAS_MSI) {
 		shared_int = false;
 		if (request_irq(irq,
-- 
2.38.1