If linear buffers requested and external buffers are not, vhost
will not be able to receive any buffer that doesn't fit in a
single mbuf. Moreover, if such a buffer will appear in a vring
it will never be dequeued and the whole vring will become dead
breaking the network connection.
Disable segmentation offloading from the host side to avoid
having such a big buffers.
Cc: Flavio Leitner <f...@sysclose.org>
Fixes: 5005bcda7123 ("vhost: add support for large buffers")
Signed-off-by: Ilya Maximets <i.maxim...@ovn.org>
---
There is still an assumption that users are sane enough to have
MTU sized mbufs in a memory pool and that guest will not change
MTU to higher values.
We, probably, still need to have a check on dequeue path and
drop oversized buffers in case of linear buffers to avoid stuck
of the virtqueue. Or simply drop support of '+linear -extbuf'
case.
Note: Only compile tested due to lack of HW.
lib/librte_vhost/socket.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
index 2d3d20804..1036eaad4 100644
--- a/lib/librte_vhost/socket.c
+++ b/lib/librte_vhost/socket.c
@@ -933,6 +933,24 @@ rte_vhost_driver_register(const char *path, uint64_t flags)
~(1ULL << VHOST_USER_PROTOCOL_F_PAGEFAULT);
}
+ /*
+ * We'll not be able to receive a buffer from guest in linear mode
+ * without external buffer if it will not fit in a single mbuf, which is
+ * likely if segmentation offloading enabled.
+ */
+ if (vsocket->linearbuf && !vsocket->extbuf) {
+ uint64_t seg_offload_features =
+ (1ULL << VIRTIO_NET_F_HOST_TSO4) |
+ (1ULL << VIRTIO_NET_F_HOST_TSO6) |
+ (1ULL << VIRTIO_NET_F_HOST_UFO);
+
+ RTE_LOG(INFO, VHOST_CONFIG,
+ "Linear buffers requested without external buffers, "
+ "disabling host segmentation offloading support\n");
+ vsocket->supported_features &= ~seg_offload_features;
+ vsocket->features &= ~seg_offload_features;
+ }
+
if (!(flags & RTE_VHOST_USER_IOMMU_SUPPORT)) {
vsocket->supported_features &= ~(1ULL <<
VIRTIO_F_IOMMU_PLATFORM);
vsocket->features &= ~(1ULL << VIRTIO_F_IOMMU_PLATFORM);
--
2.17.1
