[dpdk-stable] [PATCH v6 3/3] vhost: prevent zero copy mode if iommu is on

[Adrian Moreno <amorenoz@redhat.com>]

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: maxime.coquelin@redhat.com
Cc: stable@dpdk.org

Reviewed-by: Tiwei Bie <tiwei.bie@intel.com>
Signed-off-by: Adrian Moreno <amorenoz@redhat.com>

---
 lib/librte_vhost/socket.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
index 274988c4d..810049c15 100644
--- 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.
-- 
2.21.0