[dpdk-dev] [PATCH v2 5/9] net/virtio: setup rxq interrupts

Jianfeng Tan jianfeng.tan at intel.com
Thu Dec 29 08:30:39 CET 2016


This patch mainly allocates structure to store queue/irq mapping,
and configure queue/irq mapping down through PCI ops. It also creates
eventfds for each Rx queue and tell the kernel about the eventfd/intr
binding.

Mostly importantly, different from previous NICs (usually implements
these logic in dev_start()), virtio's interrupt settings should be
configured down to QEMU before sending DRIVER_OK notification.

Note: We only support 1:1 queue/irq mapping so far, which means, each
rx queue has one exclusive interrupt (corresponding to irqfd in the
qemu/kvm) to get notified when packets are available on that queue.

Signed-off-by: Jianfeng Tan <jianfeng.tan at intel.com>
---
 drivers/net/virtio/virtio_ethdev.c | 89 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 3f8b90c..082346b 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -1206,6 +1206,76 @@ rx_func_get(struct rte_eth_dev *eth_dev)
 		eth_dev->rx_pkt_burst = &virtio_recv_pkts;
 }
 
+/* Only support 1:1 queue/interrupt mapping so far.
+ * TODO: under below cases, lsc and rxq interrupt share one interrupt.
+ * a) binded to uio, igb_uio, vfio (type1);
+ * b) device only has one vec, see _vectors_ option in -device virtio-net-pci.
+ * TODO: support n:1 queue/interrupt mapping.
+ */
+static int
+virtio_queues_bind_intr(struct rte_eth_dev *dev)
+{
+	uint32_t i;
+	struct rte_intr_handle *intr_handle = &dev->pci_dev->intr_handle;
+	struct virtio_hw *hw = dev->data->dev_private;
+
+	PMD_INIT_LOG(INFO, "queue/interrupt binding\n");
+	for (i = 0; i < dev->data->nb_rx_queues; ++i) {
+		intr_handle->intr_vec[i] = i + 1;
+		if (vtpci_irq_queue(hw->vqs[i * VTNET_CQ], i + 1) ==
+			VIRTIO_MSI_NO_VECTOR) {
+			PMD_DRV_LOG(ERR, "failed to set queue vector");
+			return -EBUSY;
+		}
+	}
+
+	return 0;
+}
+
+static int
+virtio_configure_intr(struct rte_eth_dev *dev)
+{
+	uint32_t intr_vector;
+	struct rte_intr_handle *intr_handle = &dev->pci_dev->intr_handle;
+
+	/* check if rxq interrupt is enabled */
+	if (!rte_intr_cap_multiple(intr_handle)) {
+		PMD_INIT_LOG(ERR, "Multiple intr vector not supported");
+		return -ENOTSUP;
+	}
+
+	intr_vector = dev->data->nb_rx_queues;
+	if (rte_intr_efd_enable(intr_handle, intr_vector)) {
+		PMD_INIT_LOG(ERR, "Fail to create eventfd");
+		return -1;
+	}
+
+	if (!intr_handle->intr_vec) {
+		intr_handle->intr_vec =
+			rte_zmalloc("intr_vec", intr_vector * sizeof(int), 0);
+		if (!intr_handle->intr_vec) {
+			PMD_INIT_LOG(ERR, "Failed to allocate %d rxq vectors",
+				     intr_vector);
+			return -ENOMEM;
+		}
+	}
+
+	if (virtio_queues_bind_intr(dev) < 0) {
+		PMD_INIT_LOG(ERR, "Failed to bind queue/interrupt");
+		return -1;
+	}
+
+	/* DO NOT try remove this! This function will enable msix, or QEMU
+	 * will encounter SIGSEGV.
+	 */
+	if (rte_intr_enable(intr_handle) < 0) {
+		PMD_DRV_LOG(ERR, "interrupt enable failed");
+		return -1;
+	}
+
+	return 0;
+}
+
 /* reset device and renegotiate features if needed */
 static int
 virtio_init_device(struct rte_eth_dev *eth_dev, uint64_t req_features)
@@ -1299,6 +1369,17 @@ virtio_init_device(struct rte_eth_dev *eth_dev, uint64_t req_features)
 	ret = virtio_alloc_queues(eth_dev);
 	if (ret < 0)
 		return ret;
+
+	/* Make sure rxq interrupt is configured before sending DRIVER_OK,
+	 * so that QEMU can properly set those irq into kvm.
+	 */
+	if (eth_dev->data->dev_conf.intr_conf.rxq) {
+		if (virtio_configure_intr(eth_dev) < 0) {
+			PMD_INIT_LOG(ERR, "failed to configure interrupt");
+			return -1;
+		}
+	}
+
 	vtpci_reinit_complete(hw);
 
 	if (pci_dev)
@@ -1503,7 +1584,15 @@ virtio_dev_start(struct rte_eth_dev *dev)
 			PMD_DRV_LOG(ERR, "link status not supported by host");
 			return -ENOTSUP;
 		}
+	}
 
+	/* Enable uio/vfio intr/eventfd mapping: althrough we already did that
+	 * in device configure, but it could be unmapped  when device is
+	 * stopped.
+	 */
+	if (dev->data->dev_conf.intr_conf.lsc ||
+	    dev->data->dev_conf.intr_conf.rxq) {
+		rte_intr_disable(&dev->pci_dev->intr_handle);
 		if (rte_intr_enable(&dev->pci_dev->intr_handle) < 0) {
 			PMD_DRV_LOG(ERR, "interrupt enable failed");
 			return -EIO;
-- 
2.7.4



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