Commit dcb10c00 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

vhost-user: add protocol feature negotiation 



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: default avatarMichael S. Tsirkin <address@hidden>
Signed-off-by: default avatarYuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarYuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: default avatarMarcel Apfelbaum <marcel@redhat.com>
Tested-by: default avatarMarcel Apfelbaum <marcel@redhat.com>
parent 7305483a

docs/specs/vhost-user.txt

+37 −0
Original line number Diff line number Diff line
@@ -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

hw/net/vhost_net.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

hw/virtio/vhost-user.c

+31 −0
Original line number Diff line number Diff line
@@ -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;

}

include/hw/virtio/vhost.h

+1 −0
Original line number Diff line number Diff line
@@ -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;