Re: [Qemu-devel] [PATCH V7 08/16] virtio: introduce bus specific queue limit

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Apr 23, 2015 at 02:21:41PM +0800, Jason Wang wrote:
> This patch introduces a bus specific queue limitation. It will be
> useful for increasing the limit for one of the bus without disturbing
> other buses.
> 
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Alexander Graf <agraf@suse.de>
> Cc: Richard Henderson <rth@twiddle.net>
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>

Is this still needed if you drop the attempt to
keep the limit around for old machine types?

> ---
>  hw/char/virtio-serial-bus.c    |  2 +-
>  hw/net/virtio-net.c            |  4 ++--
>  hw/s390x/s390-virtio-bus.c     |  1 +
>  hw/s390x/virtio-ccw.c          |  1 +
>  hw/scsi/virtio-scsi.c          |  4 ++--
>  hw/virtio/virtio-mmio.c        |  1 +
>  hw/virtio/virtio-pci.c         |  1 +
>  hw/virtio/virtio.c             | 40 +++++++++++++++++++++++++---------------
>  include/hw/virtio/virtio-bus.h |  1 +
>  include/hw/virtio/virtio.h     |  1 +
>  10 files changed, 36 insertions(+), 20 deletions(-)
> 
> diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
> index e336bdb..0694831 100644
> --- a/hw/char/virtio-serial-bus.c
> +++ b/hw/char/virtio-serial-bus.c
> @@ -973,7 +973,7 @@ static void virtio_serial_device_realize(DeviceState *dev, Error **errp)
>      }
>  
>      /* Each port takes 2 queues, and one pair is for the control queue */
> -    max_supported_ports = VIRTIO_PCI_QUEUE_MAX / 2 - 1;
> +    max_supported_ports = virtio_get_queue_max(vdev) / 2 - 1;
>  
>      if (vser->serial.max_virtserial_ports > max_supported_ports) {
>          error_setg(errp, "maximum ports supported: %u", max_supported_ports);
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index b6fac9c..bf286f5 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1588,10 +1588,10 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
>      virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size);
>  
>      n->max_queues = MAX(n->nic_conf.peers.queues, 1);
> -    if (n->max_queues * 2 + 1 > VIRTIO_PCI_QUEUE_MAX) {
> +    if (n->max_queues * 2 + 1 > virtio_get_queue_max(vdev)) {
>          error_setg(errp, "Invalid number of queues (= %" PRIu32 "), "
>                     "must be a postive integer less than %d.",
> -                   n->max_queues, (VIRTIO_PCI_QUEUE_MAX - 1) / 2);
> +                   n->max_queues, (virtio_get_queue_max(vdev) - 1) / 2);
>          virtio_cleanup(vdev);
>          return;
>      }
> diff --git a/hw/s390x/s390-virtio-bus.c b/hw/s390x/s390-virtio-bus.c
> index 047c963..2b41e32 100644
> --- a/hw/s390x/s390-virtio-bus.c
> +++ b/hw/s390x/s390-virtio-bus.c
> @@ -715,6 +715,7 @@ static void virtio_s390_bus_class_init(ObjectClass *klass, void *data)
>      bus_class->max_dev = 1;
>      k->notify = virtio_s390_notify;
>      k->get_features = virtio_s390_get_features;
> +    k->queue_max = VIRTIO_PCI_QUEUE_MAX;
>  }
>  
>  static const TypeInfo virtio_s390_bus_info = {
> diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
> index 0434f56..590eed5 100644
> --- a/hw/s390x/virtio-ccw.c
> +++ b/hw/s390x/virtio-ccw.c
> @@ -1715,6 +1715,7 @@ static void virtio_ccw_bus_class_init(ObjectClass *klass, void *data)
>      k->load_queue = virtio_ccw_load_queue;
>      k->save_config = virtio_ccw_save_config;
>      k->load_config = virtio_ccw_load_config;
> +    k->queue_max = VIRTIO_PCI_QUEUE_MAX;
>  }
>  
>  static const TypeInfo virtio_ccw_bus_info = {
> diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
> index c9bea06..fbdde2b 100644
> --- a/hw/scsi/virtio-scsi.c
> +++ b/hw/scsi/virtio-scsi.c
> @@ -826,10 +826,10 @@ void virtio_scsi_common_realize(DeviceState *dev, Error **errp,
>                  sizeof(VirtIOSCSIConfig));
>  
>      if (s->conf.num_queues == 0 ||
> -            s->conf.num_queues > VIRTIO_PCI_QUEUE_MAX - 2) {
> +            s->conf.num_queues > virtio_get_queue_max(vdev) - 2) {
>          error_setg(errp, "Invalid number of queues (= %" PRIu32 "), "
>                           "must be a positive integer less than %d.",
> -                   s->conf.num_queues, VIRTIO_PCI_QUEUE_MAX - 2);
> +                   s->conf.num_queues, virtio_get_queue_max(vdev) - 2);
>          virtio_cleanup(vdev);
>          return;
>      }
> diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
> index 10123f3..2ae6942 100644
> --- a/hw/virtio/virtio-mmio.c
> +++ b/hw/virtio/virtio-mmio.c
> @@ -403,6 +403,7 @@ static void virtio_mmio_bus_class_init(ObjectClass *klass, void *data)
>      k->device_plugged = virtio_mmio_device_plugged;
>      k->has_variable_vring_alignment = true;
>      bus_class->max_dev = 1;
> +    k->queue_max = VIRTIO_PCI_QUEUE_MAX;
>  }
>  
>  static const TypeInfo virtio_mmio_bus_info = {
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index c7c3f72..075b13b 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1498,6 +1498,7 @@ static void virtio_pci_bus_class_init(ObjectClass *klass, void *data)
>      k->vmstate_change = virtio_pci_vmstate_change;
>      k->device_plugged = virtio_pci_device_plugged;
>      k->device_unplugged = virtio_pci_device_unplugged;
> +    k->queue_max = VIRTIO_PCI_QUEUE_MAX;
>  }
>  
>  static const TypeInfo virtio_pci_bus_info = {
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 17c1260..bbb224f 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -541,6 +541,14 @@ void virtio_update_irq(VirtIODevice *vdev)
>      virtio_notify_vector(vdev, VIRTIO_NO_VECTOR);
>  }
>  
> +int virtio_get_queue_max(VirtIODevice *vdev)
> +{
> +    BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> +    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> +
> +    return k->queue_max;
> +}
> +
>  void virtio_set_status(VirtIODevice *vdev, uint8_t val)
>  {
>      VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
> @@ -599,7 +607,7 @@ void virtio_reset(void *opaque)
>      vdev->config_vector = VIRTIO_NO_VECTOR;
>      virtio_notify_vector(vdev, vdev->config_vector);
>  
> -    for(i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
> +    for (i = 0; i < virtio_get_queue_max(vdev); i++) {
>          vdev->vq[i].vring.desc = 0;
>          vdev->vq[i].vring.avail = 0;
>          vdev->vq[i].vring.used = 0;
> @@ -738,7 +746,8 @@ int virtio_queue_get_num(VirtIODevice *vdev, int n)
>  int virtio_queue_get_id(VirtQueue *vq)
>  {
>      VirtIODevice *vdev = vq->vdev;
> -    assert(vq >= &vdev->vq[0] && vq < &vdev->vq[VIRTIO_PCI_QUEUE_MAX]);
> +
> +    assert(vq >= &vdev->vq[0] && vq < &vdev->vq[virtio_get_queue_max(vdev)]);
>      return vq - &vdev->vq[0];
>  }
>  
> @@ -774,28 +783,29 @@ void virtio_queue_notify(VirtIODevice *vdev, int n)
>  
>  uint16_t virtio_queue_vector(VirtIODevice *vdev, int n)
>  {
> -    return n < VIRTIO_PCI_QUEUE_MAX ? vdev->vq[n].vector :
> +    return n < virtio_get_queue_max(vdev) ? vdev->vq[n].vector :
>          VIRTIO_NO_VECTOR;
>  }
>  
>  void virtio_queue_set_vector(VirtIODevice *vdev, int n, uint16_t vector)
>  {
> -    if (n < VIRTIO_PCI_QUEUE_MAX)
> +    if (n < virtio_get_queue_max(vdev))
>          vdev->vq[n].vector = vector;
>  }
>  
>  VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
>                              void (*handle_output)(VirtIODevice *, VirtQueue *))
>  {
> -    int i;
> +    int i, queue_max = virtio_get_queue_max(vdev);
>  
> -    for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
> +    for (i = 0; i < queue_max; i++) {
>          if (vdev->vq[i].vring.num == 0)
>              break;
>      }
>  
> -    if (i == VIRTIO_PCI_QUEUE_MAX || queue_size > VIRTQUEUE_MAX_SIZE)
> +    if (i == queue_max || queue_size > VIRTQUEUE_MAX_SIZE) {
>          abort();
> +    }
>  
>      vdev->vq[i].vring.num = queue_size;
>      vdev->vq[i].vring.align = VIRTIO_PCI_VRING_ALIGN;
> @@ -806,7 +816,7 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
>  
>  void virtio_del_queue(VirtIODevice *vdev, int n)
>  {
> -    if (n < 0 || n >= VIRTIO_PCI_QUEUE_MAX) {
> +    if (n < 0 || n >= virtio_get_queue_max(vdev)) {
>          abort();
>      }
>  
> @@ -916,14 +926,14 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
>      qemu_put_be32(f, vdev->config_len);
>      qemu_put_buffer(f, vdev->config, vdev->config_len);
>  
> -    for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
> +    for (i = 0; i < k->queue_max; i++) {
>          if (vdev->vq[i].vring.num == 0)
>              break;
>      }
>  
>      qemu_put_be32(f, i);
>  
> -    for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
> +    for (i = 0; i < k->queue_max; i++) {
>          if (vdev->vq[i].vring.num == 0)
>              break;
>  
> @@ -988,7 +998,7 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
>      qemu_get_8s(f, &vdev->status);
>      qemu_get_8s(f, &vdev->isr);
>      qemu_get_be16s(f, &vdev->queue_sel);
> -    if (vdev->queue_sel >= VIRTIO_PCI_QUEUE_MAX) {
> +    if (vdev->queue_sel >= k->queue_max) {
>          return -1;
>      }
>      qemu_get_be32s(f, &features);
> @@ -1015,7 +1025,7 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
>  
>      num = qemu_get_be32(f);
>  
> -    if (num > VIRTIO_PCI_QUEUE_MAX) {
> +    if (num > k->queue_max) {
>          error_report("Invalid number of PCI queues: 0x%x", num);
>          return -1;
>      }
> @@ -1125,15 +1135,15 @@ void virtio_instance_init_common(Object *proxy_obj, void *data,
>  void virtio_init(VirtIODevice *vdev, const char *name,
>                   uint16_t device_id, size_t config_size)
>  {
> -    int i;
> +    int i, queue_max = virtio_get_queue_max(vdev);
>      vdev->device_id = device_id;
>      vdev->status = 0;
>      vdev->isr = 0;
>      vdev->queue_sel = 0;
>      vdev->config_vector = VIRTIO_NO_VECTOR;
> -    vdev->vq = g_malloc0(sizeof(VirtQueue) * VIRTIO_PCI_QUEUE_MAX);
> +    vdev->vq = g_malloc0(sizeof(VirtQueue) * queue_max);
>      vdev->vm_running = runstate_is_running();
> -    for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
> +    for (i = 0; i < queue_max; i++) {
>          vdev->vq[i].vector = VIRTIO_NO_VECTOR;
>          vdev->vq[i].vdev = vdev;
>          vdev->vq[i].queue_index = i;
> diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h
> index 0d2e7b4..4da8022 100644
> --- a/include/hw/virtio/virtio-bus.h
> +++ b/include/hw/virtio/virtio-bus.h
> @@ -68,6 +68,7 @@ typedef struct VirtioBusClass {
>       * Note that changing this will break migration for this transport.
>       */
>      bool has_variable_vring_alignment;
> +    uint16_t queue_max;
>  } VirtioBusClass;
>  
>  struct VirtioBusState {
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index d95f8b6..91fd673 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -179,6 +179,7 @@ void virtio_queue_notify(VirtIODevice *vdev, int n);
>  uint16_t virtio_queue_vector(VirtIODevice *vdev, int n);
>  void virtio_queue_set_vector(VirtIODevice *vdev, int n, uint16_t vector);
>  void virtio_set_status(VirtIODevice *vdev, uint8_t val);
> +int virtio_get_queue_max(VirtIODevice *vdev);
>  void virtio_reset(void *opaque);
>  void virtio_update_irq(VirtIODevice *vdev);
>  int virtio_set_features(VirtIODevice *vdev, uint32_t val);
> -- 
> 2.1.0