[dpdk-stable] [PATCH] net/iavf: fix vector id assignment

[dapengx.yu at intel.com]

From: YU DAPENG <dapengx.yu at intel.com>

The number of MSI-X interrupts on Rx shall be the minimal value of the
number of available MSI-X interrupts per VF - 1 (the 1 is for
miscellaneous interrupt) and the number of configured Rx queues.
The current code break the rule because the number of available MSI-X
interrupts is used as the first value, but code does not subtract 1
from it.

In normal situation, the first value is larger than the second value. So
each queue can be assigned a unique vector_id.

For example: 17 available MSI-X interrupts, and 16 available Rx queues
per VF; but only 4 Rx queues are configured when device is started.
vector_id:0 is for misc interrupt, vector_id:1 for Rx queue0,
vector_id:2 for Rx queue1, vector_id:3 for Rx queue2, vector_id:4 for Rx
queue3.

Current code breaks the rule in this normal situation, because when
assign vector_ids to interrupt handle, for example, it does not assign
vector_id:4 to the queue3, but assign vector_id:1 to it, because the
condition used causes vector_id wrap around too early.

In iavf_config_irq_map(), the current code does not write data into the
last element of vecmap[], because of the previous code break. Which
cause wrong data is sent to PF with opcode VIRTCHNL_OP_CONFIG_IRQ_MAP
and cause error: VIRTCHNL_STATUS_ERR_PARAM(-5).

If kernel driver supports large VFs (up to 256 queues), different queues
can be assigned same vector_id.

In order to adapt to large VFs and avoid wrapping early, the condition
is replaced from vec >= vf->nb_msix to vec >= vf->vf_res->max_vectors.

Fixes: d6bde6b5eae9 ("net/avf: enable Rx interrupt")
Cc: stable at dpdk.org

Signed-off-by: YU DAPENG <dapengx.yu at intel.com>
---
 drivers/net/iavf/iavf_ethdev.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/iavf/iavf_ethdev.c b/drivers/net/iavf/iavf_ethdev.c
index 7e3c26a94..d730bb156 100644
--- a/drivers/net/iavf/iavf_ethdev.c
+++ b/drivers/net/iavf/iavf_ethdev.c
@@ -483,6 +483,7 @@ static int iavf_config_rx_queues_irqs(struct rte_eth_dev *dev,
 	struct iavf_qv_map *qv_map;
 	uint16_t interval, i;
 	int vec;
+	uint16_t max_vectors;
 
 	if (rte_intr_cap_multiple(intr_handle) &&
 	    dev->data->dev_conf.intr_conf.rxq) {
@@ -570,15 +571,16 @@ static int iavf_config_rx_queues_irqs(struct rte_eth_dev *dev,
 			/* If Rx interrupt is reuquired, and we can use
 			 * multi interrupts, then the vec is from 1
 			 */
-			vf->nb_msix = RTE_MIN(vf->vf_res->max_vectors,
-					      intr_handle->nb_efd);
+			max_vectors =
+				vf->vf_res->max_vectors - IAVF_RX_VEC_START;
+			vf->nb_msix = RTE_MIN(max_vectors, intr_handle->nb_efd);
 			vf->msix_base = IAVF_RX_VEC_START;
 			vec = IAVF_RX_VEC_START;
 			for (i = 0; i < dev->data->nb_rx_queues; i++) {
 				qv_map[i].queue_id = i;
 				qv_map[i].vector_id = vec;
 				intr_handle->intr_vec[i] = vec++;
-				if (vec >= vf->nb_msix)
+				if (vec >= vf->vf_res->max_vectors)
 					vec = IAVF_RX_VEC_START;
 			}
 			vf->qv_map = qv_map;
-- 
2.27.0