[dpdk-dev] [PATCH v4 4/4] virtio: return 1 to tell the upper layer we don't take over this device

[Huawei Xie <huawei.xie@intel.com>]

v4 changes:
 Rebase as io port map is moved to eal.
 Only fall back to PORT IO when there isn't any kernel driver (including
VFIO/UIO) managing the device. Before v4, we fall back to PORT IO even if
VFIO/UIO fails.
 Reword the commit message.

v3 changes:
 Change log message to tell user that the virtio device is skipped
due to it is managed by kernel driver, instead of asking user to
unbind it from kernel driver.

v2 changes:
 Remove unnecessary assignment of NULL to dev->data->mac_addrs.
 Ajust one comment's position.

virtio PMD could use IO port to configure the virtio device without
using UIO/VFIO driver in legacy mode.

There are two issues with the previous implementation:
1) virtio PMD will take over the virtio device(s) blindly even if not
intended for DPDK.
2) driver conflict between virtio PMD and virtio-net kernel driver.

This patch checks if there is kernel driver other than UIO/VFIO managing
the virtio device before using port IO.

If legacy_virtio_resource_init fails and kernel driver other than
VFIO/UIO is managing the device, return 1 to tell the upper layer we
don't take over this device.
For all other IO port mapping errors, return -1.

Note than if VFIO/UIO fails, now we don't fall back to port IO.

Fixes: da978dfdc43b ("virtio: use port IO to get PCI resource")

Signed-off-by: Huawei Xie <huawei.xie@intel.com>
---
 drivers/net/virtio/virtio_ethdev.c |  9 +++++++--
 drivers/net/virtio/virtio_pci.c    | 15 ++++++++++++++-
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index caa970c..8601080 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -1,4 +1,5 @@
 /*-
+
  *   BSD LICENSE
  *
  *   Copyright(c) 2010-2015 Intel Corporation. All rights reserved.
@@ -1015,6 +1016,7 @@ eth_virtio_dev_init(struct rte_eth_dev *eth_dev)
 	struct virtio_net_config *config;
 	struct virtio_net_config local_config;
 	struct rte_pci_device *pci_dev;
+	int ret;
 
 	RTE_BUILD_BUG_ON(RTE_PKTMBUF_HEADROOM < sizeof(struct virtio_net_hdr));
 
@@ -1037,8 +1039,11 @@ eth_virtio_dev_init(struct rte_eth_dev *eth_dev)
 
 	pci_dev = eth_dev->pci_dev;
 
-	if (vtpci_init(pci_dev, hw) < 0)
-		return -1;
+	ret = vtpci_init(pci_dev, hw);
+	if (ret) {
+		rte_free(eth_dev->data->mac_addrs);
+		return ret;
+	}
 
 	/* Reset the device although not necessary at startup */
 	vtpci_reset(hw);
diff --git a/drivers/net/virtio/virtio_pci.c b/drivers/net/virtio/virtio_pci.c
index 85fbe88..f159b2a 100644
--- a/drivers/net/virtio/virtio_pci.c
+++ b/drivers/net/virtio/virtio_pci.c
@@ -622,6 +622,13 @@ next:
 	return 0;
 }
 
+/*
+ * Return -1:
+ *   if there is error mapping with VFIO/UIO.
+ *   if port map error when driver type is KDRV_NONE.
+ * Return 1 if kernel driver is managing the device.
+ * Return 0 on success.
+ */
 int
 vtpci_init(struct rte_pci_device *dev, struct virtio_hw *hw)
 {
@@ -641,8 +648,14 @@ vtpci_init(struct rte_pci_device *dev, struct virtio_hw *hw)
 	}
 
 	PMD_INIT_LOG(INFO, "trying with legacy virtio pci.");
-	if (legacy_virtio_resource_init(dev, hw) < 0)
+	if (legacy_virtio_resource_init(dev, hw) < 0) {
+		if (dev->kdrv == RTE_KDRV_UNKNOWN) {
+			PMD_INIT_LOG(INFO,
+				"skip kernel managed virtio device.");
+			return 1;
+		}
 		return -1;
+	}
 
 	hw->vtpci_ops = &legacy_ops;
 	hw->use_msix = legacy_virtio_has_msix(&dev->addr);
-- 
1.8.1.4