[dpdk-dev] [PATCH] vfio: use right index when tracking devices in a vfio group

[Alejandro Lucero <alejandro.lucero@netronome.com>]

Previous fix for properly handling devices from the same VFIO group
introduced another bug where the file descriptor of a kernel vfio
group is used as the index for tracking number of devices of a vfio
group struct handled by dpdk vfio code. Instead of the file
descriptor itself, the vfio group object that file descriptor is
registered with has to be used.

This patch introduces specific functions for incrementing or
decrementing the device counter for a specific vfio group using the
vfio file descriptor as a parameter. Note the code is not optimized
as the vfio group is found sequentially going through the vfio group
array but this should not be a problem as this is not related to
packet handling at all.

Fixes: a9c349e3a100 ("vfio: fix device unplug when several devices per group")

Signed-off-by: Alejandro Lucero <alejandro.lucero@netronome.com>
---
 lib/librte_eal/linuxapp/eal/eal_vfio.c | 60 +++++++++++++++++++++++++++-------
 1 file changed, 49 insertions(+), 11 deletions(-)

diff --git a/lib/librte_eal/linuxapp/eal/eal_vfio.c b/lib/librte_eal/linuxapp/eal/eal_vfio.c
index d3eae20..21d126f 100644
--- a/lib/librte_eal/linuxapp/eal/eal_vfio.c
+++ b/lib/librte_eal/linuxapp/eal/eal_vfio.c
@@ -172,6 +172,44 @@
 	return -1;
 }
 
+
+static int
+get_vfio_group_idx(int vfio_group_fd)
+{
+	int i;
+	for (i = 0; i < VFIO_MAX_GROUPS; i++)
+		if (vfio_cfg.vfio_groups[i].fd == vfio_group_fd)
+			return i;
+	return -1;
+}
+
+static void
+vfio_group_device_get(int vfio_group_fd)
+{
+	int i;
+
+	i = get_vfio_group_idx(vfio_group_fd);
+	vfio_cfg.vfio_groups[i].devices++;
+}
+
+static void
+vfio_group_device_put(int vfio_group_fd)
+{
+	int i;
+
+	i = get_vfio_group_idx(vfio_group_fd);
+	vfio_cfg.vfio_groups[i].devices--;
+}
+
+static int
+vfio_group_device_count(int vfio_group_fd)
+{
+	int i;
+
+	i = get_vfio_group_idx(vfio_group_fd);
+	return vfio_cfg.vfio_groups[i].devices;
+}
+
 int
 clear_group(int vfio_group_fd)
 {
@@ -180,15 +218,14 @@
 
 	if (internal_config.process_type == RTE_PROC_PRIMARY) {
 
-		for (i = 0; i < VFIO_MAX_GROUPS; i++)
-			if (vfio_cfg.vfio_groups[i].fd == vfio_group_fd) {
-				vfio_cfg.vfio_groups[i].group_no = -1;
-				vfio_cfg.vfio_groups[i].fd = -1;
-				vfio_cfg.vfio_groups[i].devices = 0;
-				vfio_cfg.vfio_active_groups--;
-				return 0;
-			}
-		return -1;
+		i = get_vfio_group_idx(vfio_group_fd);
+		if ( i < 0)
+			return -1;
+		vfio_cfg.vfio_groups[i].group_no = -1;
+		vfio_cfg.vfio_groups[i].fd = -1;
+		vfio_cfg.vfio_groups[i].devices = 0;
+		vfio_cfg.vfio_active_groups--;
+		return 0;
 	}
 
 	/* This is just for SECONDARY processes */
@@ -358,7 +395,7 @@
 		clear_group(vfio_group_fd);
 		return -1;
 	}
-	vfio_cfg.vfio_groups[vfio_group_fd].devices++;
+	vfio_group_device_get(vfio_group_fd);
 
 	return 0;
 }
@@ -406,7 +443,8 @@
 	/* An VFIO group can have several devices attached. Just when there is
 	 * no devices remaining should the group be closed.
 	 */
-	if (--vfio_cfg.vfio_groups[vfio_group_fd].devices == 0) {
+	vfio_group_device_put(vfio_group_fd);
+	if (!vfio_group_device_count(vfio_group_fd)) {
 
 		if (close(vfio_group_fd) < 0) {
 			RTE_LOG(INFO, EAL, "Error when closing vfio_group_fd for %s\n",
-- 
1.9.1