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vhost: advertise support in-order feature

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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>
This commit is contained in:
Marvin Liu 2018-07-02 21:56:34 +08:00 committed by Ferruh Yigit
parent 246c5cc5f0
commit 22d2e78840
2 changed files with 15 additions and 1 deletions
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6
lib/librte_vhost/socket.c
View File

@ -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);

10
lib/librte_vhost/vhost.h
View File

@ -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))