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[PATCH v2 2/7] libvhost-user: advertise vring features
From: |
Stefan Hajnoczi |
Subject: |
[PATCH v2 2/7] libvhost-user: advertise vring features |
Date: |
Tue, 9 Jun 2020 18:02:13 +0100 |
libvhost-user implements several vring features without advertising
them. There is no way for the vhost-user master to detect support for
these features.
Things more or less work today because QEMU assumes the vhost-user
backend always implements certain feature bits like
VIRTIO_RING_F_EVENT_IDX. This is not documented anywhere.
This patch explicitly advertises features implemented in libvhost-user
so that the vhost-user master does not need to make undocumented
assumptions.
Feature bits that libvhost-user now advertises can be removed from
vhost-user-blk.c. Devices should not be responsible for advertising
vring feature bits, that is libvhost-user's job.
Cc: Jason Wang <jasowang@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
I have tested make check and virtiofsd.
---
contrib/libvhost-user/libvhost-user.c | 10 ++++++++++
contrib/vhost-user-blk/vhost-user-blk.c | 4 +---
2 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/contrib/libvhost-user/libvhost-user.c
b/contrib/libvhost-user/libvhost-user.c
index 3bca996c62..b43874ba12 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -495,6 +495,16 @@ static bool
vu_get_features_exec(VuDev *dev, VhostUserMsg *vmsg)
{
vmsg->payload.u64 =
+ /*
+ * The following VIRTIO feature bits are supported by our virtqueue
+ * implementation:
+ */
+ 1ULL << VIRTIO_F_NOTIFY_ON_EMPTY |
+ 1ULL << VIRTIO_RING_F_INDIRECT_DESC |
+ 1ULL << VIRTIO_RING_F_EVENT_IDX |
+ 1ULL << VIRTIO_F_VERSION_1 |
+
+ /* vhost-user feature bits */
1ULL << VHOST_F_LOG_ALL |
1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
diff --git a/contrib/vhost-user-blk/vhost-user-blk.c
b/contrib/vhost-user-blk/vhost-user-blk.c
index 6fd91c7e99..25eccd02b5 100644
--- a/contrib/vhost-user-blk/vhost-user-blk.c
+++ b/contrib/vhost-user-blk/vhost-user-blk.c
@@ -382,9 +382,7 @@ vub_get_features(VuDev *dev)
1ull << VIRTIO_BLK_F_DISCARD |
1ull << VIRTIO_BLK_F_WRITE_ZEROES |
#endif
- 1ull << VIRTIO_BLK_F_CONFIG_WCE |
- 1ull << VIRTIO_F_VERSION_1 |
- 1ull << VHOST_USER_F_PROTOCOL_FEATURES;
+ 1ull << VIRTIO_BLK_F_CONFIG_WCE;
if (vdev_blk->enable_ro) {
features |= 1ull << VIRTIO_BLK_F_RO;
--
2.26.2
- [PATCH v2 0/7] virtio: enable VIRTIO_F_RING_PACKED for all devices, Stefan Hajnoczi, 2020/06/09
- [PATCH v2 1/7] tests/libqos: mask out VIRTIO_F_RING_PACKED for now, Stefan Hajnoczi, 2020/06/09
- [PATCH v2 2/7] libvhost-user: advertise vring features,
Stefan Hajnoczi <=
- [PATCH v2 3/7] docs: document non-net VHOST_USER_GET_FEATURES behavior, Stefan Hajnoczi, 2020/06/09
- [PATCH v2 4/7] vhost: involve device backends in feature negotiation, Stefan Hajnoczi, 2020/06/09
- Re: [PATCH v2 4/7] vhost: involve device backends in feature negotiation, Michael S. Tsirkin, 2020/06/09
- Re: [PATCH v2 4/7] vhost: involve device backends in feature negotiation, Jason Wang, 2020/06/09
- Re: [PATCH v2 4/7] vhost: involve device backends in feature negotiation, Michael S. Tsirkin, 2020/06/10
- Re: [PATCH v2 4/7] vhost: involve device backends in feature negotiation, Jason Wang, 2020/06/10
- Re: [PATCH v2 4/7] vhost: involve device backends in feature negotiation, Michael S. Tsirkin, 2020/06/10
- Re: [PATCH v2 4/7] vhost: involve device backends in feature negotiation, Jason Wang, 2020/06/10
Re: [PATCH v2 4/7] vhost: involve device backends in feature negotiation, Michael S. Tsirkin, 2020/06/10