[dpdk-dev] [PATCH] vhost: initializing iotlb memory only when IOMMU feature is enabled.

[Nitin Katiyar <nitin.katiyar@ericsson.com>]

DPDK 17.11 introduced the IOMMU feature which caused additional
DPDK memory requirement per vhostuser device as part of
iotlb_init(). Today this is done unconditionally (from DPDK
17.11 onwards) i.e. irrespective of IOMMU feature being
enabled on the vhostuser device, iotlb is initialized. This
breaks the backward compatibility for applications like OVS
due to increase in the DPDK memory footprint and causes upgrade
failures.

This patch is to do iotlb_init only if IOMMU feature is
enabled on device.

Signed-off-by: Nitin Katiyar <nitin.katiyar@ericsson.com>
---
 lib/librte_vhost/iotlb.c      | 7 +++++++
 lib/librte_vhost/vhost_user.c | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/lib/librte_vhost/iotlb.c b/lib/librte_vhost/iotlb.c
index c6354fe..befa2d3 100644
--- a/lib/librte_vhost/iotlb.c
+++ b/lib/librte_vhost/iotlb.c
@@ -317,6 +317,13 @@ struct vhost_iotlb_entry {
 	struct vhost_virtqueue *vq = dev->virtqueue[vq_index];
 	int socket = 0;
 
+	if (!(dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))) {
+		RTE_LOG(INFO, VHOST_CONFIG,
+			"IOMMU feature is not enabled for this dev(%s)\n",
+			dev->ifname);
+		return 0;
+	}
+
 	if (vq->iotlb_pool) {
 		/*
 		 * The cache has already been initialized,
diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index a2d4c9f..7553a03 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -1366,6 +1366,12 @@
 	uint16_t i;
 	uint64_t vva, len;
 
+	if (!(dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))) {
+		RTE_LOG(ERR, VHOST_CONFIG,
+			"IOMMU feature is not enabled for this dev(%s)\n",
+			dev->ifname);
+		return -1;
+	}
 	switch (imsg->type) {
 	case VHOST_IOTLB_UPDATE:
 		len = imsg->size;
-- 
1.9.1