Commit db68f4ff authored by Stefan Hajnoczi's avatar Stefan Hajnoczi Committed by Michael S. Tsirkin
Browse files

libvhost-user: add vmsg_set_reply_u64() helper 



The VhostUserMsg request is reused as the reply by message processing
functions.  This is risky since request fields may corrupt the reply if
the vhost-user message handler function forgets to re-initialize them.

Changing this practice would be very invasive but we can introduce a
helper function to make u64 payload replies safe.  This also eliminates
code duplication in message processing functions.

Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190626074815.19994-2-stefanha@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 457cfccc

contrib/libvhost-user/libvhost-user.c

+13 −13
Original line number Diff line number Diff line
@@ -216,6 +216,15 @@ vmsg_close_fds(VhostUserMsg *vmsg) 
    }

}



/* Set reply payload.u64 and clear request flags and fd_num */

static void vmsg_set_reply_u64(VhostUserMsg *vmsg, uint64_t val)

{

    vmsg->flags = 0; /* defaults will be set by vu_send_reply() */

    vmsg->size = sizeof(vmsg->payload.u64);

    vmsg->payload.u64 = val;

    vmsg->fd_num = 0;

}



/* A test to see if we have userfault available */

static bool

have_userfault(void)
@@ -1168,10 +1177,7 @@ vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg) 
        features |= dev->iface->get_protocol_features(dev);

    }



    vmsg->payload.u64 = features;

    vmsg->size = sizeof(vmsg->payload.u64);

    vmsg->fd_num = 0;



    vmsg_set_reply_u64(vmsg, features);

    return true;

}
@@ -1307,17 +1313,14 @@ out: 
static bool

vu_set_postcopy_listen(VuDev *dev, VhostUserMsg *vmsg)

{

    vmsg->payload.u64 = -1;

    vmsg->size = sizeof(vmsg->payload.u64);



    if (dev->nregions) {

        vu_panic(dev, "Regions already registered at postcopy-listen");

        vmsg_set_reply_u64(vmsg, -1);

        return true;

    }

    dev->postcopy_listening = true;



    vmsg->flags = VHOST_USER_VERSION |  VHOST_USER_REPLY_MASK;

    vmsg->payload.u64 = 0; /* Success */

    vmsg_set_reply_u64(vmsg, 0);

    return true;

}
@@ -1332,10 +1335,7 @@ vu_set_postcopy_end(VuDev *dev, VhostUserMsg *vmsg) 
        DPRINT("%s: Done close\n", __func__);

    }



    vmsg->fd_num = 0;

    vmsg->payload.u64 = 0;

    vmsg->size = sizeof(vmsg->payload.u64);

    vmsg->flags = VHOST_USER_VERSION |  VHOST_USER_REPLY_MASK;

    vmsg_set_reply_u64(vmsg, 0);

    DPRINT("%s: exit\n", __func__);

    return true;

}