From 3a1470e031ff33ac99da33b41dae0e9082d4da78 Mon Sep 17 00:00:00 2001
From: Damjan Marion <damarion@cisco.com>
Date: Mon, 15 May 2017 12:27:37 +0200
Subject: [PATCH] Revert "net/virtio: remove redundant MSI-X detection"

This reverts commit ee1843bd89076c59e50cadbef5c935613f543765.
---
 drivers/net/virtio/virtio_pci.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/net/virtio/virtio_pci.c b/drivers/net/virtio/virtio_pci.c
index b7b3d6157..127f25791 100644
--- a/drivers/net/virtio/virtio_pci.c
+++ b/drivers/net/virtio/virtio_pci.c
@@ -274,6 +274,32 @@ legacy_notify_queue(struct virtio_hw *hw, struct virtqueue *vq)
 		VIRTIO_PCI_QUEUE_NOTIFY);
 }
 
+#ifdef RTE_EXEC_ENV_LINUXAPP
+static int
+legacy_virtio_has_msix(const struct rte_pci_addr *loc)
+{
+	DIR *d;
+	char dirname[PATH_MAX];
+
+	snprintf(dirname, sizeof(dirname),
+		     "%s/" PCI_PRI_FMT "/msi_irqs", pci_get_sysfs_path(),
+		     loc->domain, loc->bus, loc->devid, loc->function);
+
+	d = opendir(dirname);
+	if (d)
+		closedir(d);
+
+	return d != NULL;
+}
+#else
+static int
+legacy_virtio_has_msix(const struct rte_pci_addr *loc __rte_unused)
+{
+	/* nic_uio does not enable interrupts, return 0 (false). */
+	return 0;
+}
+#endif
+
 const struct virtio_pci_ops legacy_ops = {
 	.read_dev_cfg	= legacy_read_dev_config,
 	.write_dev_cfg	= legacy_write_dev_config,
@@ -694,6 +720,7 @@ vtpci_init(struct rte_pci_device *dev, struct virtio_hw *hw)
 	}
 
 	virtio_hw_internal[hw->port_id].vtpci_ops = &legacy_ops;
+	hw->use_msix = legacy_virtio_has_msix(&dev->addr);
 	hw->modern   = 0;
 
 	return 0;
-- 
2.11.0