[dpdk-dev] [RFC 10/10] vhost: enable postcopy protocol feature

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Enable postcopy protocol feature except if dequeue
zero-copy is enabled. In this case, guest memory requires
to be populated, which is not compatible with userfaultfd.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/vhost_user.c | 7 +++++++
 lib/librte_vhost/vhost_user.h | 3 ++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 54692775c..1a31d8551 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -1235,6 +1235,13 @@ vhost_user_get_protocol_features(struct virtio_net *dev,
 	if (!(features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)))
 		protocol_features &= ~(1ULL << VHOST_USER_PROTOCOL_F_REPLY_ACK);
 
+	/*
+	 * If dequeue zerocopy is enabled, guest memory requires to be
+	 * populated, which is not compatible with postcopy.
+	 */
+	if (dev->dequeue_zero_copy)
+		protocol_features &= ~(1ULL << VHOST_USER_PROTOCOL_F_PAGEFAULT);
+
 	msg->payload.u64 = protocol_features;
 	msg->size = sizeof(msg->payload.u64);
 	msg->fd_num = 0;
diff --git a/lib/librte_vhost/vhost_user.h b/lib/librte_vhost/vhost_user.h
index 73b1fe2b9..dc97be843 100644
--- a/lib/librte_vhost/vhost_user.h
+++ b/lib/librte_vhost/vhost_user.h
@@ -22,7 +22,8 @@
 					 (1ULL << VHOST_USER_PROTOCOL_F_SLAVE_REQ) | \
 					 (1ULL << VHOST_USER_PROTOCOL_F_CRYPTO_SESSION) | \
 					 (1ULL << VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD) | \
-					 (1ULL << VHOST_USER_PROTOCOL_F_HOST_NOTIFIER))
+					 (1ULL << VHOST_USER_PROTOCOL_F_HOST_NOTIFIER) | \
+					 (1ULL << VHOST_USER_PROTOCOL_F_PAGEFAULT))
 
 typedef enum VhostUserRequest {
 	VHOST_USER_NONE = 0,
-- 
2.17.1