| Message ID | 20221019125210.226291-4-eperezma@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Guest announce feature emulation using Shadow VirtQueue | expand |
On Wed, Oct 19, 2022 at 8:52 PM Eugenio Pérez <eperezma@redhat.com> wrote: > > At this moment this code path is not reached, but vdpa devices can offer > VIRTIO_NET_F_STATUS unconditionally. So I guess what you mean is that, for the parent that doesn't support VIRTIO_NET_F_STATUS, emulate one for making sure the ANNOUCNE to work. This is safe since the spec said the driver will assume the link is always up if without this feature. > While the guest must assume that > link is always up by the standard, qemu will set the status bit to 1 > always in this case. > > This makes little use by itself, but VIRTIO_NET_F_STATUS is needed for > the guest to read status bit VIRTIO_NET_F_GUEST_ANNOUNCE, used by feature > VIRTIO_NET_F_GUEST_ANNOUNCE. So qemu must emulate status feature in case > it needs to emulate the guest announce feature. > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com> > --- > hw/net/vhost_net.c | 27 ++++++++++++++++++++++++++- > 1 file changed, 26 insertions(+), 1 deletion(-) > > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c > index d28f8b974b..5660606c1d 100644 > --- a/hw/net/vhost_net.c > +++ b/hw/net/vhost_net.c > @@ -117,7 +117,32 @@ uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t features) > int vhost_net_get_config(struct vhost_net *net, uint8_t *config, > uint32_t config_len) > { > - return vhost_dev_get_config(&net->dev, config, config_len, NULL); > + VirtIODevice *vdev; > + int r = vhost_dev_get_config(&net->dev, config, config_len, NULL); > + > + if (unlikely(r != 0)) { > + return r; > + } > + > + if (config_len < endof(struct virtio_net_config, status)) { > + return 0; > + } > + > + /* > + * TODO: Perform this only if vhost_vdpa. > + */ Cindy adds some mediation codes for vhost-vDPA in virtio_net_get_config(), so I believe it can be done there? Thanks > + vdev = net->dev.vdev; > + if (!vdev) { > + /* Device is starting */ > + return 0; > + } > + > + if ((net->dev.acked_features & BIT_ULL(VIRTIO_NET_F_STATUS)) && > + !(net->dev.features & BIT_ULL(VIRTIO_NET_F_STATUS))) { > + ((struct virtio_net_config *)config)->status |= VIRTIO_NET_S_LINK_UP; > + } > + > + return 0; > } > int vhost_net_set_config(struct vhost_net *net, const uint8_t *data, > uint32_t offset, uint32_t size, uint32_t flags) > -- > 2.31.1 >
On Thu, Oct 20, 2022 at 6:30 AM Jason Wang <jasowang@redhat.com> wrote: > > On Wed, Oct 19, 2022 at 8:52 PM Eugenio Pérez <eperezma@redhat.com> wrote: > > > > At this moment this code path is not reached, but vdpa devices can offer > > VIRTIO_NET_F_STATUS unconditionally. > > So I guess what you mean is that, for the parent that doesn't support > VIRTIO_NET_F_STATUS, emulate one for making sure the ANNOUCNE to work. > This is safe since the spec said the driver will assume the link is > always up if without this feature. > Right. > > While the guest must assume that > > link is always up by the standard, qemu will set the status bit to 1 > > always in this case. > > > > This makes little use by itself, but VIRTIO_NET_F_STATUS is needed for > > the guest to read status bit VIRTIO_NET_F_GUEST_ANNOUNCE, used by feature > > VIRTIO_NET_F_GUEST_ANNOUNCE. So qemu must emulate status feature in case > > it needs to emulate the guest announce feature. > > > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com> > > --- > > hw/net/vhost_net.c | 27 ++++++++++++++++++++++++++- > > 1 file changed, 26 insertions(+), 1 deletion(-) > > > > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c > > index d28f8b974b..5660606c1d 100644 > > --- a/hw/net/vhost_net.c > > +++ b/hw/net/vhost_net.c > > @@ -117,7 +117,32 @@ uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t features) > > int vhost_net_get_config(struct vhost_net *net, uint8_t *config, > > uint32_t config_len) > > { > > - return vhost_dev_get_config(&net->dev, config, config_len, NULL); > > + VirtIODevice *vdev; > > + int r = vhost_dev_get_config(&net->dev, config, config_len, NULL); > > + > > + if (unlikely(r != 0)) { > > + return r; > > + } > > + > > + if (config_len < endof(struct virtio_net_config, status)) { > > + return 0; > > + } > > + > > + /* > > + * TODO: Perform this only if vhost_vdpa. > > + */ > > Cindy adds some mediation codes for vhost-vDPA in > virtio_net_get_config(), so I believe it can be done there? > Sure, let me take a look. Thanks! > Thanks > > > + vdev = net->dev.vdev; > > + if (!vdev) { > > + /* Device is starting */ > > + return 0; > > + } > > + > > + if ((net->dev.acked_features & BIT_ULL(VIRTIO_NET_F_STATUS)) && > > + !(net->dev.features & BIT_ULL(VIRTIO_NET_F_STATUS))) { > > + ((struct virtio_net_config *)config)->status |= VIRTIO_NET_S_LINK_UP; > > + } > > + > > + return 0; > > } > > int vhost_net_set_config(struct vhost_net *net, const uint8_t *data, > > uint32_t offset, uint32_t size, uint32_t flags) > > -- > > 2.31.1 > > >
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c index d28f8b974b..5660606c1d 100644 --- a/hw/net/vhost_net.c +++ b/hw/net/vhost_net.c @@ -117,7 +117,32 @@ uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t features) int vhost_net_get_config(struct vhost_net *net, uint8_t *config, uint32_t config_len) { - return vhost_dev_get_config(&net->dev, config, config_len, NULL); + VirtIODevice *vdev; + int r = vhost_dev_get_config(&net->dev, config, config_len, NULL); + + if (unlikely(r != 0)) { + return r; + } + + if (config_len < endof(struct virtio_net_config, status)) { + return 0; + } + + /* + * TODO: Perform this only if vhost_vdpa. + */ + vdev = net->dev.vdev; + if (!vdev) { + /* Device is starting */ + return 0; + } + + if ((net->dev.acked_features & BIT_ULL(VIRTIO_NET_F_STATUS)) && + !(net->dev.features & BIT_ULL(VIRTIO_NET_F_STATUS))) { + ((struct virtio_net_config *)config)->status |= VIRTIO_NET_S_LINK_UP; + } + + return 0; } int vhost_net_set_config(struct vhost_net *net, const uint8_t *data, uint32_t offset, uint32_t size, uint32_t flags)
At this moment this code path is not reached, but vdpa devices can offer VIRTIO_NET_F_STATUS unconditionally. While the guest must assume that link is always up by the standard, qemu will set the status bit to 1 always in this case. This makes little use by itself, but VIRTIO_NET_F_STATUS is needed for the guest to read status bit VIRTIO_NET_F_GUEST_ANNOUNCE, used by feature VIRTIO_NET_F_GUEST_ANNOUNCE. So qemu must emulate status feature in case it needs to emulate the guest announce feature. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> --- hw/net/vhost_net.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)