vhost: prevent zero copy mode if IOMMU is on

The simultaneous use of dequeue_zero_copy and IOMMU is problematic.
Not only because IOVA_VA mode is not supported but also because the
potential invalidation of guest pages while the buffers are in use,
is not handled.

Prevent these two features to be enabled simultaneously.

Fixes: 69c90e98f483 ("vhost: enable IOMMU support")
Cc: stable@dpdk.org
Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
Reviewed-by: Tiwei Bie <tiwei.bie@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
index 274988c..810049c 100644 (file)
--- a/lib/librte_vhost/socket.c
+++ b/lib/librte_vhost/socket.c
@@ -871,6 +871,14 @@ rte_vhost_driver_register(const char *path, uint64_t flags)
        }
        vsocket->dequeue_zero_copy = flags & RTE_VHOST_USER_DEQUEUE_ZERO_COPY;
 
+       if (vsocket->dequeue_zero_copy &&
+           (flags & RTE_VHOST_USER_IOMMU_SUPPORT)) {
+               RTE_LOG(ERR, VHOST_CONFIG,
+                       "error: enabling dequeue zero copy and IOMMU features "
+                       "simultaneously is not supported\n");
+               goto out_mutex;
+       }
+
        /*
         * Set the supported features correctly for the builtin vhost-user
         * net driver.