Re: [Qemu-devel] [RFC PATCH V4 2/6] virtio-bus : Introduce virtio-bus

[Peter Maydell <peter.maydell@linaro.org>]

On 30 November 2012 17:12,  <fred.konrad@greensocs.com> wrote:
> From: KONRAD Frederic <fred.konrad@greensocs.com>
>
> Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
> ---
>  hw/Makefile.objs |    1 +
>  hw/virtio-bus.c  |  114 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  hw/virtio-bus.h  |   78 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 193 insertions(+), 0 deletions(-)
>  create mode 100644 hw/virtio-bus.c
>  create mode 100644 hw/virtio-bus.h
>
> diff --git a/hw/Makefile.objs b/hw/Makefile.objs
> index d581d8d..6fa4de4 100644
> --- a/hw/Makefile.objs
> +++ b/hw/Makefile.objs
> @@ -3,6 +3,7 @@ common-obj-y += loader.o
>  common-obj-$(CONFIG_VIRTIO) += virtio-console.o
>  common-obj-$(CONFIG_VIRTIO) += virtio-rng.o
>  common-obj-$(CONFIG_VIRTIO_PCI) += virtio-pci.o
> +common-obj-$(CONFIG_VIRTIO) += virtio-bus.o
>  common-obj-y += fw_cfg.o
>  common-obj-$(CONFIG_PCI) += pci.o pci_bridge.o pci_bridge_dev.o
>  common-obj-$(CONFIG_PCI) += msix.o msi.o
> diff --git a/hw/virtio-bus.c b/hw/virtio-bus.c
> new file mode 100644
> index 0000000..ed9c146
> --- /dev/null
> +++ b/hw/virtio-bus.c
> @@ -0,0 +1,114 @@
> +/*
> + * VirtioBus
> + *
> + *  Copyright (C) 2012 : GreenSocs Ltd
> + *      http://www.greensocs.com/ , email: info@greensocs.com
> + *
> + *  Developed by :
> + *  Frederic Konrad   <fred.konrad@greensocs.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation, either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> + * with this program; if not, see <http://www.gnu.org/licenses/>.
> + *
> + */
> +
> +#include "hw.h"
> +#include "qemu-error.h"
> +#include "qdev.h"
> +#include "virtio-bus.h"
> +#include "virtio.h"
> +
> +#define DEBUG_VIRTIO_BUS

Don't enable debug by default.

> +
> +#ifdef DEBUG_VIRTIO_BUS
> +#define DPRINTF(fmt, ...) \
> +do { printf("virtio_bus: " fmt , ## __VA_ARGS__); } while (0)
> +#else
> +#define DPRINTF(fmt, ...) do { } while (0)
> +#endif
> +
> +/* Is the bus used ? */
> +static inline int virtio_bus_in_use(VirtioBusState *bus)
> +{
> +    return (bus->vdev != NULL);
> +}
> +
> +/* Plug the VirtIODevice */
> +int virtio_bus_plug_device(VirtioBusState *bus, VirtIODevice *vdev)
> +{
> +    BusState *qbus = BUS(bus);
> +    VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);
> +    DPRINTF("plug device into %s.\n", qbus->name);
> +    if (virtio_bus_in_use(bus)) {
> +        /*
> +         * that couldn't be reached if we modify qdev-monitor.c
> +         * ( see other patch ).
> +         */
> +        error_report("%s in use.\n", qbus->name);
> +        return -1;

You can assume that patch 1 in your series has been applied
here: just assert(bus->vdev == NULL) (and drop the virtio_bus_in_use
function).

> +    }
> +
> +    /* keep the VirtIODevice in the VirtioBus. */

This comment is useless: say something useful, not something which
is obvious from the code.

> +    bus->vdev = vdev;
> +
> +    /* call the "transport" callback. */
> +    if (klass->init != NULL) {
> +        klass->init(qbus->parent);
> +    }

Comment and code disagree about what's happening.

> +    return 0;
> +}
> +
> +/* Bind the VirtIODevice to the VirtioBus. */
> +void virtio_bus_bind_device(VirtioBusState *bus)
> +{
> +    BusState *qbus = BUS(bus);
> +    VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);
> +    assert(bus != NULL);
> +    assert(bus->vdev != NULL);
> +    /*
> +     * The lines below will disappear, as we will refactor virtio-device.
> +     */
> +    bus->bindings.notify = klass->notify;
> +    bus->bindings.save_config = klass->save_config;
> +    bus->bindings.save_queue = klass->save_queue;
> +    bus->bindings.load_config = klass->load_config;
> +    bus->bindings.load_queue = klass->load_queue;
> +    bus->bindings.load_done = klass->load_done;
> +    bus->bindings.get_features = klass->get_features;
> +    bus->bindings.query_guest_notifiers = klass->query_guest_notifiers;
> +    bus->bindings.set_guest_notifiers = klass->set_guest_notifiers;
> +    bus->bindings.set_host_notifier = klass->set_host_notifier;
> +    bus->bindings.vmstate_change = klass->vmstate_change;
> +    virtio_bind_device(bus->vdev, &(bus->bindings), qbus->parent);
> +}
> +
> +/* Return the virtio device id of the plugged device. */
> +uint16_t get_virtio_device_id(VirtioBusState *bus)
> +{
> +    return bus->vdev->device_id;
> +}
> +
> +static const TypeInfo virtio_bus_info = {
> +    .name = TYPE_VIRTIO_BUS,
> +    .parent = TYPE_BUS,
> +    .instance_size = sizeof(VirtioBusState),
> +    .abstract = true,
> +    .class_size = sizeof(VirtioBusClass),
> +};
> +
> +static void virtio_register_types(void)
> +{
> +    type_register_static(&virtio_bus_info);
> +}
> +
> +type_init(virtio_register_types)
> diff --git a/hw/virtio-bus.h b/hw/virtio-bus.h
> new file mode 100644
> index 0000000..90ae67c
> --- /dev/null
> +++ b/hw/virtio-bus.h
> @@ -0,0 +1,78 @@
> +/*
> + * VirtioBus
> + *
> + *  Copyright (C) 2012 : GreenSocs Ltd
> + *      http://www.greensocs.com/ , email: info@greensocs.com
> + *
> + *  Developed by :
> + *  Frederic Konrad   <fred.konrad@greensocs.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation, either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> + * with this program; if not, see <http://www.gnu.org/licenses/>.
> + *
> + */
> +
> +#ifndef VIRTIO_BUS_H
> +#define VIRTIO_BUS_H
> +
> +#include "qdev.h"
> +#include "sysemu.h"
> +#include "virtio.h"
> +
> +#define TYPE_VIRTIO_BUS "virtio-bus"
> +#define VIRTIO_BUS_GET_CLASS(obj) \
> +        OBJECT_GET_CLASS(VirtioBusClass, obj, TYPE_VIRTIO_BUS)
> +#define VIRTIO_BUS_CLASS(klass) \
> +        OBJECT_CLASS_CHECK(VirtioBusClass, klass, TYPE_VIRTIO_BUS)
> +#define VIRTIO_BUS(obj) OBJECT_CHECK(VirtioBusState, (obj), TYPE_VIRTIO_BUS)
> +
> +typedef struct VirtioBusState VirtioBusState;
> +
> +typedef struct VirtioBusClass {
> +    /* This is what a VirtioBus must implement */
> +    BusClass parent;
> +    /* Old VirtioBindings */

This is not a particularly useful comment. There's an opportunity
here to provide some doc comments which describe what all these
callbacks a VirtioBus must implement are for.

> +    void (*notify)(void *opaque, uint16_t vector);
> +    void (*save_config)(void *opaque, QEMUFile *f);
> +    void (*save_queue)(void *opaque, int n, QEMUFile *f);
> +    int (*load_config)(void *opaque, QEMUFile *f);
> +    int (*load_queue)(void *opaque, int n, QEMUFile *f);
> +    int (*load_done)(void *opaque, QEMUFile *f);
> +    unsigned (*get_features)(void *opaque);
> +    bool (*query_guest_notifiers)(void *opaque);
> +    int (*set_guest_notifiers)(void *opaque, bool assigned);
> +    int (*set_host_notifier)(void *opaque, int n, bool assigned);
> +    void (*vmstate_change)(void *opaque, bool running);
> +    /* transport independent init function. */
> +    void (*init)(void *opaque);
> +    /* transport independent exit function. */
> +    void (*exit)(void *opaque);
> +} VirtioBusClass;
> +
> +struct VirtioBusState {
> +    BusState parent_obj;
> +    /*
> +     * Only one VirtIODevice can be plugged on the bus.
> +     */
> +    VirtIODevice *vdev;
> +    /*
> +     * This should be removed when we refactor virtio-device.
> +     */
> +    VirtIOBindings bindings;
> +};
> +
> +void virtio_bus_bind_device(VirtioBusState *bus);
> +int virtio_bus_plug_device(VirtioBusState *bus, VirtIODevice *vdev);
> +uint16_t get_virtio_device_id(VirtioBusState *bus);
> +
> +#endif /* VIRTIO_BUS_H */
> --
> 1.7.1
>

-- PMM