From 2752b89ead002d1f07d840db0e925f3229e0f178 Mon Sep 17 00:00:00 2001
From: Damjan Marion <damarion@cisco.com>
Date: Mon, 11 Dec 2017 15:55:56 +0100
Subject: [PATCH] pci: auto-detect right vfio/uio driver

Change-Id: Ib4012ff598698924484525932d041988cc4c63f6
Signed-off-by: Damjan Marion <damarion@cisco.com>
---
 src/plugins/dpdk/device/init.c |  2 +-
 src/vlib/linux/pci.c           | 55 ++++++++++++++++++++++++++++++++++++++++++
 src/vpp/conf/startup.conf      |  4 +--
 3 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/src/plugins/dpdk/device/init.c b/src/plugins/dpdk/device/init.c
index a6b6440f230..6041a3ca2a8 100755
--- a/src/plugins/dpdk/device/init.c
+++ b/src/plugins/dpdk/device/init.c
@@ -1035,7 +1035,7 @@ dpdk_config (vlib_main_t * vm, unformat_input_t * input)
     }
 
   if (!conf->uio_driver_name)
-    conf->uio_driver_name = format (0, "uio_pci_generic%c", 0);
+    conf->uio_driver_name = format (0, "auto%c", 0);
 
   /*
    * Use 1G huge pages if available.
diff --git a/src/vlib/linux/pci.c b/src/vlib/linux/pci.c
index 69dcdd0d760..62edcf4f8b6 100644
--- a/src/vlib/linux/pci.c
+++ b/src/vlib/linux/pci.c
@@ -56,6 +56,8 @@
 
 static const char *sysfs_pci_dev_path = "/sys/bus/pci/devices";
 static const char *sysfs_pci_drv_path = "/sys/bus/pci/drivers";
+static char *sysfs_mod_vfio_noiommu =
+  "/sys/module/vfio/parameters/enable_unsafe_noiommu_mode";
 
 typedef struct
 {
@@ -314,6 +316,16 @@ done:
   return di;
 }
 
+static int
+directory_exists (char *path)
+{
+  struct stat s = { 0 };
+  if (stat (path, &s) == -1)
+    return 0;
+
+  return S_ISDIR (s.st_mode);
+}
+
 clib_error_t *
 vlib_pci_bind_to_uio (vlib_pci_addr_t * addr, char *uio_drv_name)
 {
@@ -331,6 +343,49 @@ vlib_pci_bind_to_uio (vlib_pci_addr_t * addr, char *uio_drv_name)
   if (error)
     return error;
 
+  if (strncmp ("auto", uio_drv_name, 5) == 0)
+    {
+      int vfio_pci_loaded = 0;
+
+      if (directory_exists ("/sys/module/vfio_pci"))
+	vfio_pci_loaded = 1;
+
+      if (di->iommu_group != -1)
+	{
+	  /* device is bound to IOMMU group */
+	  if (!vfio_pci_loaded)
+	    {
+	      error = clib_error_return (0, "Skipping PCI device %U: device "
+					 "is bound to IOMMU group and "
+					 "vfio-pci driver is not loaded",
+					 format_vlib_pci_addr, addr);
+	      goto done;
+	    }
+	  else
+	    uio_drv_name = "vfio-pci";
+	}
+      else
+	{
+	  /* device is not bound to IOMMU group so we have multiple options */
+	  if (vfio_pci_loaded &&
+	      (error = clib_sysfs_write (sysfs_mod_vfio_noiommu, "Y")) == 0)
+	    uio_drv_name = "vfio-pci";
+	  else if (directory_exists ("/sys/module/uio_pci_generic"))
+	    uio_drv_name = "uio_pci_generic";
+	  else if (directory_exists ("/sys/module/igb_uio"))
+	    uio_drv_name = "igb_uio";
+	  else
+	    {
+	      clib_error_free (error);
+	      error = clib_error_return (0, "Skipping PCI device %U: missing "
+					 "kernel VFIO or UIO driver",
+					 format_vlib_pci_addr, addr);
+	      goto done;
+	    }
+	  clib_error_free (error);
+	}
+    }
+
   s = format (s, "%v/driver%c", dev_dir_name, 0);
   driver_name = clib_sysfs_link_to_name ((char *) s);
   vec_reset_length (s);
diff --git a/src/vpp/conf/startup.conf b/src/vpp/conf/startup.conf
index 304dd1fab3f..b18c6743869 100644
--- a/src/vpp/conf/startup.conf
+++ b/src/vpp/conf/startup.conf
@@ -105,8 +105,8 @@ cpu {
 	# vdev eth_bond0,mode=1,slave=0000:02:00.0,slave=0000:03:00.0
 	# vdev eth_bond1,mode=1,slave=0000:02:00.1,slave=0000:03:00.1
 
-	## Change UIO driver used by VPP, Options are: igb_uio, vfio-pci
-	## and uio_pci_generic (default)
+	## Change UIO driver used by VPP, Options are: igb_uio, vfio-pci,
+	## uio_pci_generic or auto (default)
 	# uio-driver vfio-pci
 
 	## Disable mutli-segment buffers, improves performance but
-- 
2.16.6