| Message ID | 1442982001-10669-3-git-send-email-yuanhan.liu@linux.intel.com |
|---|---|
| State | New |
| Headers | show |
On 09/23/2015 07:19 AM, Yuanhan Liu wrote: > From: "Michael S. Tsirkin" <mst@redhat.com> > > Support a separate bitmask for vhost-user protocol features, > and messages to get/set protocol features. > > Invoke them at init. > > No features are defined yet. > > [ leverage vhost_user_call for request handling -- Yuanhan Liu ] > > Signed-off-by: Michael S. Tsirkin <address@hidden> > Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com> > --- > docs/specs/vhost-user.txt | 37 +++++++++++++++++++++++++++++++++++++ > hw/net/vhost_net.c | 2 ++ > hw/virtio/vhost-user.c | 31 +++++++++++++++++++++++++++++++ > include/hw/virtio/vhost.h | 1 + > 4 files changed, 71 insertions(+) > > diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt > index 650bb18..70da3b1 100644 > --- a/docs/specs/vhost-user.txt > +++ b/docs/specs/vhost-user.txt > @@ -113,6 +113,7 @@ message replies. Most of the requests don't require replies. Here is a list of > the ones that do: > > * VHOST_GET_FEATURES > + * VHOST_GET_PROTOCOL_FEATURES > * VHOST_GET_VRING_BASE > > There are several messages that the master sends with file descriptors passed > @@ -127,6 +128,13 @@ in the ancillary data: > If Master is unable to send the full message or receives a wrong reply it will > close the connection. An optional reconnection mechanism can be implemented. > > +Any protocol extensions are gated by protocol feature bits, > +which allows full backwards compatibility on both master > +and slave. > +As older slaves don't support negotiating protocol features, > +a feature bit was dedicated for this purpose: > +#define VHOST_USER_F_PROTOCOL_FEATURES 30 > + > Message types > ------------- > > @@ -138,6 +146,8 @@ Message types > Slave payload: u64 > > Get from the underlying vhost implementation the features bitmask. > + Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for > + VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES. > > * VHOST_USER_SET_FEATURES > > @@ -146,6 +156,33 @@ Message types > Master payload: u64 > > Enable features in the underlying vhost implementation using a bitmask. > + Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for > + VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES. > + > + * VHOST_USER_GET_PROTOCOL_FEATURES > + > + Id: 15 > + Equivalent ioctl: VHOST_GET_FEATURES VHOST_USER_GET_PROTOCOL_FEATURES does not have an equivalent ioctl > + Master payload: N/A > + Slave payload: u64 > + > + Get the protocol feature bitmask from the underlying vhost implementation. > + Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in > + VHOST_USER_GET_FEATURES. > + Note: slave that reported VHOST_USER_F_PROTOCOL_FEATURES must support > + this message even before VHOST_USER_SET_FEATURES was called. > + > + * VHOST_USER_SET_PROTOCOL_FEATURES > + > + Id: 16 > + Ioctl: VHOST_SET_FEATURES Same here > + Master payload: u64 > + > + Enable protocol features in the underlying vhost implementation. > + Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in > + VHOST_USER_GET_FEATURES. > + Note: slave that reported VHOST_USER_F_PROTOCOL_FEATURES must support > + this message even before VHOST_USER_SET_FEATURES was called. > > * VHOST_USER_SET_OWNER > > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c > index 1d76b94..9d32d76 100644 > --- a/hw/net/vhost_net.c > +++ b/hw/net/vhost_net.c > @@ -152,8 +152,10 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options) > net->dev.backend_features = qemu_has_vnet_hdr(options->net_backend) > ? 0 : (1ULL << VHOST_NET_F_VIRTIO_NET_HDR); > net->backend = r; > + net->dev.protocol_features = 0; > } else { > net->dev.backend_features = 0; > + net->dev.protocol_features = 0; > net->backend = -1; > } Maybe protocol_features assignment should be outside the if clause. (assigned to 0 in both cases) > net->nc = options->net_backend; > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c > index 13677ac..7fe35c6 100644 > --- a/hw/virtio/vhost-user.c > +++ b/hw/virtio/vhost-user.c > @@ -24,6 +24,8 @@ > #include <linux/vhost.h> > > #define VHOST_MEMORY_MAX_NREGIONS 8 > +#define VHOST_USER_F_PROTOCOL_FEATURES 30 > +#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x0ULL > > typedef enum VhostUserRequest { > VHOST_USER_NONE = 0, > @@ -41,6 +43,8 @@ typedef enum VhostUserRequest { > VHOST_USER_SET_VRING_KICK = 12, > VHOST_USER_SET_VRING_CALL = 13, > VHOST_USER_SET_VRING_ERR = 14, > + VHOST_USER_GET_PROTOCOL_FEATURES = 15, > + VHOST_USER_SET_PROTOCOL_FEATURES = 16, > VHOST_USER_MAX > } VhostUserRequest; > > @@ -206,11 +210,13 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request, > > switch (msg_request) { > case VHOST_USER_GET_FEATURES: > + case VHOST_USER_GET_PROTOCOL_FEATURES: > need_reply = 1; > break; > > case VHOST_USER_SET_FEATURES: > case VHOST_USER_SET_LOG_BASE: > + case VHOST_USER_SET_PROTOCOL_FEATURES: > msg.u64 = *((__u64 *) arg); > msg.size = sizeof(m.u64); > break; > @@ -308,6 +314,7 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request, > > switch (msg_request) { > case VHOST_USER_GET_FEATURES: > + case VHOST_USER_GET_PROTOCOL_FEATURES: > if (msg.size != sizeof(m.u64)) { > error_report("Received bad msg size."); > return -1; > @@ -333,10 +340,34 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request, > > static int vhost_user_init(struct vhost_dev *dev, void *opaque) > { > + unsigned long long features; > + int err; > + > assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER); > > dev->opaque = opaque; > > + err = vhost_user_call(dev, VHOST_USER_GET_FEATURES, &features); > + if (err < 0) { > + return err; > + } > + > + if (virtio_has_feature(features, VHOST_USER_F_PROTOCOL_FEATURES)) { > + dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES; > + > + err = vhost_user_call(dev, VHOST_USER_GET_PROTOCOL_FEATURES, &features); > + if (err < 0) { > + return err; > + } > + > + dev->protocol_features = features & VHOST_USER_PROTOCOL_FEATURE_MASK; > + err = vhost_user_call(dev, VHOST_USER_SET_PROTOCOL_FEATURES, > + &dev->protocol_features); > + if (err < 0) { > + return err; > + } > + } > + > return 0; > } > > diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h > index dd51050..6467c73 100644 > --- a/include/hw/virtio/vhost.h > +++ b/include/hw/virtio/vhost.h > @@ -47,6 +47,7 @@ struct vhost_dev { > unsigned long long features; > unsigned long long acked_features; > unsigned long long backend_features; > + unsigned long long protocol_features; > bool started; > bool log_enabled; > unsigned long long log_size; > The above comments can be addressed on top of this series because does not affect the correctness of the patch.
On Thu, Sep 24, 2015 at 01:13:24PM +0300, Marcel Apfelbaum wrote: > On 09/23/2015 07:19 AM, Yuanhan Liu wrote: > >From: "Michael S. Tsirkin" <mst@redhat.com> > > > >Support a separate bitmask for vhost-user protocol features, > >and messages to get/set protocol features. > > > >Invoke them at init. > > > >No features are defined yet. > > > >[ leverage vhost_user_call for request handling -- Yuanhan Liu ] > > > >Signed-off-by: Michael S. Tsirkin <address@hidden> > >Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com> > >--- > > docs/specs/vhost-user.txt | 37 +++++++++++++++++++++++++++++++++++++ > > hw/net/vhost_net.c | 2 ++ > > hw/virtio/vhost-user.c | 31 +++++++++++++++++++++++++++++++ > > include/hw/virtio/vhost.h | 1 + > > 4 files changed, 71 insertions(+) > > > >diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt > >index 650bb18..70da3b1 100644 > >--- a/docs/specs/vhost-user.txt > >+++ b/docs/specs/vhost-user.txt > >@@ -113,6 +113,7 @@ message replies. Most of the requests don't require replies. Here is a list of > > the ones that do: > > > > * VHOST_GET_FEATURES > >+ * VHOST_GET_PROTOCOL_FEATURES > > * VHOST_GET_VRING_BASE > > > > There are several messages that the master sends with file descriptors passed > >@@ -127,6 +128,13 @@ in the ancillary data: > > If Master is unable to send the full message or receives a wrong reply it will > > close the connection. An optional reconnection mechanism can be implemented. > > > >+Any protocol extensions are gated by protocol feature bits, > >+which allows full backwards compatibility on both master > >+and slave. > >+As older slaves don't support negotiating protocol features, > >+a feature bit was dedicated for this purpose: > >+#define VHOST_USER_F_PROTOCOL_FEATURES 30 > >+ > > Message types > > ------------- > > > >@@ -138,6 +146,8 @@ Message types > > Slave payload: u64 > > > > Get from the underlying vhost implementation the features bitmask. > >+ Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for > >+ VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES. > > > > * VHOST_USER_SET_FEATURES > > > >@@ -146,6 +156,33 @@ Message types > > Master payload: u64 > > > > Enable features in the underlying vhost implementation using a bitmask. > >+ Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for > >+ VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES. > >+ > >+ * VHOST_USER_GET_PROTOCOL_FEATURES > >+ > >+ Id: 15 > >+ Equivalent ioctl: VHOST_GET_FEATURES > > VHOST_USER_GET_PROTOCOL_FEATURES does not have an equivalent ioctl Oops, I didn't notice that. Will fix it soon, and thank you for the review! --yliu > > >+ Master payload: N/A > >+ Slave payload: u64 > >+ > >+ Get the protocol feature bitmask from the underlying vhost implementation. > >+ Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in > >+ VHOST_USER_GET_FEATURES. > >+ Note: slave that reported VHOST_USER_F_PROTOCOL_FEATURES must support > >+ this message even before VHOST_USER_SET_FEATURES was called. > >+ > >+ * VHOST_USER_SET_PROTOCOL_FEATURES > >+ > >+ Id: 16 > >+ Ioctl: VHOST_SET_FEATURES > > Same here > > >+ Master payload: u64 > >+ > >+ Enable protocol features in the underlying vhost implementation. > >+ Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in > >+ VHOST_USER_GET_FEATURES. > >+ Note: slave that reported VHOST_USER_F_PROTOCOL_FEATURES must support > >+ this message even before VHOST_USER_SET_FEATURES was called. > > > > * VHOST_USER_SET_OWNER > > > >diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c > >index 1d76b94..9d32d76 100644 > >--- a/hw/net/vhost_net.c > >+++ b/hw/net/vhost_net.c > >@@ -152,8 +152,10 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options) > > net->dev.backend_features = qemu_has_vnet_hdr(options->net_backend) > > ? 0 : (1ULL << VHOST_NET_F_VIRTIO_NET_HDR); > > net->backend = r; > >+ net->dev.protocol_features = 0; > > } else { > > net->dev.backend_features = 0; > >+ net->dev.protocol_features = 0; > > net->backend = -1; > > } > > Maybe protocol_features assignment should be outside the if clause. > (assigned to 0 in both cases) > > > net->nc = options->net_backend; > >diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c > >index 13677ac..7fe35c6 100644 > >--- a/hw/virtio/vhost-user.c > >+++ b/hw/virtio/vhost-user.c > >@@ -24,6 +24,8 @@ > > #include <linux/vhost.h> > > > > #define VHOST_MEMORY_MAX_NREGIONS 8 > >+#define VHOST_USER_F_PROTOCOL_FEATURES 30 > >+#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x0ULL > > > > typedef enum VhostUserRequest { > > VHOST_USER_NONE = 0, > >@@ -41,6 +43,8 @@ typedef enum VhostUserRequest { > > VHOST_USER_SET_VRING_KICK = 12, > > VHOST_USER_SET_VRING_CALL = 13, > > VHOST_USER_SET_VRING_ERR = 14, > >+ VHOST_USER_GET_PROTOCOL_FEATURES = 15, > >+ VHOST_USER_SET_PROTOCOL_FEATURES = 16, > > VHOST_USER_MAX > > } VhostUserRequest; > > > >@@ -206,11 +210,13 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request, > > > > switch (msg_request) { > > case VHOST_USER_GET_FEATURES: > >+ case VHOST_USER_GET_PROTOCOL_FEATURES: > > need_reply = 1; > > break; > > > > case VHOST_USER_SET_FEATURES: > > case VHOST_USER_SET_LOG_BASE: > >+ case VHOST_USER_SET_PROTOCOL_FEATURES: > > msg.u64 = *((__u64 *) arg); > > msg.size = sizeof(m.u64); > > break; > >@@ -308,6 +314,7 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request, > > > > switch (msg_request) { > > case VHOST_USER_GET_FEATURES: > >+ case VHOST_USER_GET_PROTOCOL_FEATURES: > > if (msg.size != sizeof(m.u64)) { > > error_report("Received bad msg size."); > > return -1; > >@@ -333,10 +340,34 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request, > > > > static int vhost_user_init(struct vhost_dev *dev, void *opaque) > > { > >+ unsigned long long features; > >+ int err; > >+ > > assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER); > > > > dev->opaque = opaque; > > > >+ err = vhost_user_call(dev, VHOST_USER_GET_FEATURES, &features); > >+ if (err < 0) { > >+ return err; > >+ } > >+ > >+ if (virtio_has_feature(features, VHOST_USER_F_PROTOCOL_FEATURES)) { > >+ dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES; > >+ > >+ err = vhost_user_call(dev, VHOST_USER_GET_PROTOCOL_FEATURES, &features); > >+ if (err < 0) { > >+ return err; > >+ } > >+ > >+ dev->protocol_features = features & VHOST_USER_PROTOCOL_FEATURE_MASK; > >+ err = vhost_user_call(dev, VHOST_USER_SET_PROTOCOL_FEATURES, > >+ &dev->protocol_features); > >+ if (err < 0) { > >+ return err; > >+ } > >+ } > >+ > > return 0; > > } > > > >diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h > >index dd51050..6467c73 100644 > >--- a/include/hw/virtio/vhost.h > >+++ b/include/hw/virtio/vhost.h > >@@ -47,6 +47,7 @@ struct vhost_dev { > > unsigned long long features; > > unsigned long long acked_features; > > unsigned long long backend_features; > >+ unsigned long long protocol_features; > > bool started; > > bool log_enabled; > > unsigned long long log_size; > > > > The above comments can be addressed on top of this series because > does not affect the correctness of the patch. > > -- > Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
On Thu, Sep 24, 2015 at 01:13:24PM +0300, Marcel Apfelbaum wrote: > >diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c > >index 1d76b94..9d32d76 100644 > >--- a/hw/net/vhost_net.c > >+++ b/hw/net/vhost_net.c > >@@ -152,8 +152,10 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options) > > net->dev.backend_features = qemu_has_vnet_hdr(options->net_backend) > > ? 0 : (1ULL << VHOST_NET_F_VIRTIO_NET_HDR); > > net->backend = r; > >+ net->dev.protocol_features = 0; > > } else { > > net->dev.backend_features = 0; > >+ net->dev.protocol_features = 0; > > net->backend = -1; > > } > > Maybe protocol_features assignment should be outside the if clause. > (assigned to 0 in both cases) Yeah, we could do that. However, it seems that it will take more effort, for handling patch conflicts while rebase, than it worths. Therefore I will keep it. --yliu
diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt index 650bb18..70da3b1 100644 --- a/docs/specs/vhost-user.txt +++ b/docs/specs/vhost-user.txt @@ -113,6 +113,7 @@ message replies. Most of the requests don't require replies. Here is a list of the ones that do: * VHOST_GET_FEATURES + * VHOST_GET_PROTOCOL_FEATURES * VHOST_GET_VRING_BASE There are several messages that the master sends with file descriptors passed @@ -127,6 +128,13 @@ in the ancillary data: If Master is unable to send the full message or receives a wrong reply it will close the connection. An optional reconnection mechanism can be implemented. +Any protocol extensions are gated by protocol feature bits, +which allows full backwards compatibility on both master +and slave. +As older slaves don't support negotiating protocol features, +a feature bit was dedicated for this purpose: +#define VHOST_USER_F_PROTOCOL_FEATURES 30 + Message types ------------- @@ -138,6 +146,8 @@ Message types Slave payload: u64 Get from the underlying vhost implementation the features bitmask. + Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for + VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES. * VHOST_USER_SET_FEATURES @@ -146,6 +156,33 @@ Message types Master payload: u64 Enable features in the underlying vhost implementation using a bitmask. + Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for + VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES. + + * VHOST_USER_GET_PROTOCOL_FEATURES + + Id: 15 + Equivalent ioctl: VHOST_GET_FEATURES + Master payload: N/A + Slave payload: u64 + + Get the protocol feature bitmask from the underlying vhost implementation. + Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in + VHOST_USER_GET_FEATURES. + Note: slave that reported VHOST_USER_F_PROTOCOL_FEATURES must support + this message even before VHOST_USER_SET_FEATURES was called. + + * VHOST_USER_SET_PROTOCOL_FEATURES + + Id: 16 + Ioctl: VHOST_SET_FEATURES + Master payload: u64 + + Enable protocol features in the underlying vhost implementation. + Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in + VHOST_USER_GET_FEATURES. + Note: slave that reported VHOST_USER_F_PROTOCOL_FEATURES must support + this message even before VHOST_USER_SET_FEATURES was called. * VHOST_USER_SET_OWNER diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c index 1d76b94..9d32d76 100644 --- a/hw/net/vhost_net.c +++ b/hw/net/vhost_net.c @@ -152,8 +152,10 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options) net->dev.backend_features = qemu_has_vnet_hdr(options->net_backend) ? 0 : (1ULL << VHOST_NET_F_VIRTIO_NET_HDR); net->backend = r; + net->dev.protocol_features = 0; } else { net->dev.backend_features = 0; + net->dev.protocol_features = 0; net->backend = -1; } net->nc = options->net_backend; diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 13677ac..7fe35c6 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -24,6 +24,8 @@ #include <linux/vhost.h> #define VHOST_MEMORY_MAX_NREGIONS 8 +#define VHOST_USER_F_PROTOCOL_FEATURES 30 +#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x0ULL typedef enum VhostUserRequest { VHOST_USER_NONE = 0, @@ -41,6 +43,8 @@ typedef enum VhostUserRequest { VHOST_USER_SET_VRING_KICK = 12, VHOST_USER_SET_VRING_CALL = 13, VHOST_USER_SET_VRING_ERR = 14, + VHOST_USER_GET_PROTOCOL_FEATURES = 15, + VHOST_USER_SET_PROTOCOL_FEATURES = 16, VHOST_USER_MAX } VhostUserRequest; @@ -206,11 +210,13 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request, switch (msg_request) { case VHOST_USER_GET_FEATURES: + case VHOST_USER_GET_PROTOCOL_FEATURES: need_reply = 1; break; case VHOST_USER_SET_FEATURES: case VHOST_USER_SET_LOG_BASE: + case VHOST_USER_SET_PROTOCOL_FEATURES: msg.u64 = *((__u64 *) arg); msg.size = sizeof(m.u64); break; @@ -308,6 +314,7 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request, switch (msg_request) { case VHOST_USER_GET_FEATURES: + case VHOST_USER_GET_PROTOCOL_FEATURES: if (msg.size != sizeof(m.u64)) { error_report("Received bad msg size."); return -1; @@ -333,10 +340,34 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request, static int vhost_user_init(struct vhost_dev *dev, void *opaque) { + unsigned long long features; + int err; + assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER); dev->opaque = opaque; + err = vhost_user_call(dev, VHOST_USER_GET_FEATURES, &features); + if (err < 0) { + return err; + } + + if (virtio_has_feature(features, VHOST_USER_F_PROTOCOL_FEATURES)) { + dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES; + + err = vhost_user_call(dev, VHOST_USER_GET_PROTOCOL_FEATURES, &features); + if (err < 0) { + return err; + } + + dev->protocol_features = features & VHOST_USER_PROTOCOL_FEATURE_MASK; + err = vhost_user_call(dev, VHOST_USER_SET_PROTOCOL_FEATURES, + &dev->protocol_features); + if (err < 0) { + return err; + } + } + return 0; } diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h index dd51050..6467c73 100644 --- a/include/hw/virtio/vhost.h +++ b/include/hw/virtio/vhost.h @@ -47,6 +47,7 @@ struct vhost_dev { unsigned long long features; unsigned long long acked_features; unsigned long long backend_features; + unsigned long long protocol_features; bool started; bool log_enabled; unsigned long long log_size;