[v4,1/9] vhost: advertise support in-order feature
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Commit Message
If devices always use descriptors in the same order in which they have
been made available. These devices can offer the VIRTIO_F_IN_ORDER
feature. If negotiated, this knowledge allows devices to notify the use
of a batch of buffers to virtio driver by only writing used ring index.
Vhost user device has supported this feature by default. If vhost
dequeue zero is enabled, should disable VIRTIO_F_IN_ORDER as vhost can’t
assure that descriptors returned from NIC are in order.
Signed-off-by: Marvin Liu <yong.liu@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
@@ -853,6 +853,12 @@ rte_vhost_driver_register(const char *path, uint64_t flags)
vsocket->supported_features = VIRTIO_NET_SUPPORTED_FEATURES;
vsocket->features = VIRTIO_NET_SUPPORTED_FEATURES;
+ /* Dequeue zero copy can't assure descriptors returned in order */
+ if (vsocket->dequeue_zero_copy) {
+ vsocket->supported_features &= ~(1ULL << VIRTIO_F_IN_ORDER);
+ vsocket->features &= ~(1ULL << VIRTIO_F_IN_ORDER);
+ }
+
if (!(flags & RTE_VHOST_USER_IOMMU_SUPPORT)) {
vsocket->supported_features &= ~(1ULL << VIRTIO_F_IOMMU_PLATFORM);
vsocket->features &= ~(1ULL << VIRTIO_F_IOMMU_PLATFORM);
@@ -191,6 +191,13 @@ struct vhost_msg {
#define VIRTIO_F_VERSION_1 32
#endif
+/*
+ * Available and used descs are in same order
+ */
+#ifndef VIRTIO_F_IN_ORDER
+#define VIRTIO_F_IN_ORDER 35
+#endif
+
/* Features supported by this builtin vhost-user net driver. */
#define VIRTIO_NET_SUPPORTED_FEATURES ((1ULL << VIRTIO_NET_F_MRG_RXBUF) | \
(1ULL << VIRTIO_F_ANY_LAYOUT) | \
@@ -214,7 +221,8 @@ struct vhost_msg {
(1ULL << VIRTIO_NET_F_GUEST_ECN) | \
(1ULL << VIRTIO_RING_F_INDIRECT_DESC) | \
(1ULL << VIRTIO_RING_F_EVENT_IDX) | \
- (1ULL << VIRTIO_NET_F_MTU) | \
+ (1ULL << VIRTIO_NET_F_MTU) | \
+ (1ULL << VIRTIO_F_IN_ORDER) | \
(1ULL << VIRTIO_F_IOMMU_PLATFORM))