Commit 160600fd authored by Amit Shah's avatar Amit Shah Committed by Anthony Liguori
Browse files

virtio-serial-bus: Add a port 'name' property for port discovery in guests 



The port 'id' or number is internal state between the guest kernel and
our bus implementation. This is invocation-dependent and isn't part of
the guest-host ABI.

To correcly enumerate and map ports between the host and the guest, the
'name' property is used.

Example:

    -device virtserialport,name=org.qemu.port.0

This invocation will get us a char device in the guest at:

    /dev/virtio-ports/org.qemu.port.0

which can be a symlink to

    /dev/vport0p3

This 'name' property is exposed by the guest kernel in a sysfs
attribute:

    /sys/kernel/virtio-ports/vport0p3/name

A simple udev script can pick up this name and create the symlink
mentioned above.

Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent 6663a195

hw/virtio-serial-bus.c

+17 −0
Original line number Diff line number Diff line
@@ -204,6 +204,8 @@ static void handle_control_message(VirtIOSerial *vser, void *buf) 
{

    struct VirtIOSerialPort *port;

    struct virtio_console_control cpkt, *gcpkt;

    uint8_t *buffer;

    size_t buffer_len;



    gcpkt = buf;

    port = find_port_by_id(vser, ldl_p(&gcpkt->id));
@@ -226,6 +228,21 @@ static void handle_control_message(VirtIOSerial *vser, void *buf) 
            send_control_event(port, VIRTIO_CONSOLE_CONSOLE_PORT, 1);

        }



        if (port->name) {

            stw_p(&cpkt.event, VIRTIO_CONSOLE_PORT_NAME);

            stw_p(&cpkt.value, 1);



            buffer_len = sizeof(cpkt) + strlen(port->name) + 1;

            buffer = qemu_malloc(buffer_len);



            memcpy(buffer, &cpkt, sizeof(cpkt));

            memcpy(buffer + sizeof(cpkt), port->name, strlen(port->name));

            buffer[buffer_len - 1] = 0;



            send_control_msg(port, buffer, buffer_len);

            qemu_free(buffer);

        }



        if (port->host_connected) {

            send_control_event(port, VIRTIO_CONSOLE_PORT_OPEN, 1);

        }

hw/virtio-serial.c

+1 −0
Original line number Diff line number Diff line
@@ -100,6 +100,7 @@ static VirtIOSerialPortInfo virtconsole_info = { 
    .qdev.props = (Property[]) {

        DEFINE_PROP_UINT8("is_console", VirtConsole, port.is_console, 1),

        DEFINE_PROP_CHR("chardev", VirtConsole, chr),

        DEFINE_PROP_STRING("name", VirtConsole, port.name),

        DEFINE_PROP_END_OF_LIST(),

    },

};

hw/virtio-serial.h

+8 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ struct virtio_console_control { 
#define VIRTIO_CONSOLE_CONSOLE_PORT	1

#define VIRTIO_CONSOLE_RESIZE		2

#define VIRTIO_CONSOLE_PORT_OPEN	3

#define VIRTIO_CONSOLE_PORT_NAME	4



/* == In-qemu interface == */
@@ -83,6 +84,13 @@ struct VirtIOSerialPort { 


    VirtQueue *ivq, *ovq;



    /*

     * This name is sent to the guest and exported via sysfs.

     * The guest could create symlinks based on this information.

     * The name is in the reverse fqdn format, like org.qemu.console.0

     */

    char *name;



    /*

     * This id helps identify ports between the guest and the host.

     * The guest sends a "header" with this id with each data packet