Re: [Qemu-devel] [PATCH v2 3/6] virtio: support adding sub-regions for notify region

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

On Mon, Mar 19, 2018 at 03:15:34PM +0800, Tiwei Bie wrote:
> Provide APIs to support querying whether the page-per-vq
> is enabled and adding sub-regions for notify region.
> 
> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
> ---
>  Makefile.target            |  4 ++++
>  hw/virtio/virtio-pci.c     | 48 ++++++++++++++++++++++++++++++++++++++++++++++
>  hw/virtio/virtio-pci.h     |  5 +++++
>  hw/virtio/virtio.c         | 39 +++++++++++++++++++++++++++++++++++++
>  include/hw/virtio/virtio.h |  5 +++++
>  include/qemu/osdep.h       |  1 +
>  scripts/create_config      |  3 +++
>  7 files changed, 105 insertions(+)
> 
> diff --git a/Makefile.target b/Makefile.target
> index 6549481096..b2cf618dc9 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -39,6 +39,9 @@ STPFILES=
>  config-target.h: config-target.h-timestamp
>  config-target.h-timestamp: config-target.mak
>  
> +config-devices.h: config-devices.h-timestamp
> +config-devices.h-timestamp: config-devices.mak
> +
>  ifdef CONFIG_TRACE_SYSTEMTAP
>  stap: $(QEMU_PROG).stp-installed $(QEMU_PROG).stp $(QEMU_PROG)-simpletrace.stp
>

So +config-devices.h is made from config-devices.h-timestamp
and config-devices.h-timestamp from config-devices.mak

What is config-devices.mak made from?

  
> @@ -224,4 +227,5 @@ ifdef CONFIG_TRACE_SYSTEMTAP
>  endif
>  
>  GENERATED_FILES += config-target.h
> +GENERATED_FILES += config-devices.h
>  Makefile: $(GENERATED_FILES)
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 1e8ab7bbc5..b17471092a 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1534,6 +1534,54 @@ static void virtio_pci_modern_io_region_unmap(VirtIOPCIProxy *proxy,
>                                  &region->mr);
>  }
>  
> +static VirtIOPCIProxy *virtio_device_to_virtio_pci_proxy(VirtIODevice *vdev)
> +{
> +    VirtIOPCIProxy *proxy = NULL;
> +
> +    if (vdev->device_id == VIRTIO_ID_NET) {
> +        VirtIONetPCI *d = container_of(vdev, VirtIONetPCI, vdev.parent_obj);
> +        proxy = &d->parent_obj;
> +    }
> +
> +    return proxy;
> +}
> +
> +bool virtio_pci_page_per_vq_enabled(VirtIODevice *vdev)
> +{
> +    VirtIOPCIProxy *proxy = virtio_device_to_virtio_pci_proxy(vdev);
> +
> +    if (proxy == NULL) {
> +        return false;
> +    }
> +
> +    return !!(proxy->flags & VIRTIO_PCI_FLAG_PAGE_PER_VQ);
> +}
> +

VIRTIO_PCI_FLAG_PAGE_PER_VQ is not something external users
should care about. Need to find some other way to express the
specific requirements.

In particular do you want to use a host page per VQ?

This isn't what VIRTIO_PCI_FLAG_PAGE_PER_VQ does - it uses a 4K offset
which does not match a memory page size on all platforms.


> +int virtio_pci_notify_region_map(VirtIODevice *vdev, int queue_idx,
> +                                 MemoryRegion *mr)
> +{
> +    VirtIOPCIProxy *proxy = virtio_device_to_virtio_pci_proxy(vdev);
> +    int offset;
> +
> +    if (proxy == NULL || !virtio_pci_modern(proxy)) {
> +        return -1;
> +    }
> +
> +    offset = virtio_pci_queue_mem_mult(proxy) * queue_idx;
> +    memory_region_add_subregion(&proxy->notify.mr, offset, mr);
> +
> +    return 0;
> +}
> +
> +void virtio_pci_notify_region_unmap(VirtIODevice *vdev, MemoryRegion *mr)
> +{
> +    VirtIOPCIProxy *proxy = virtio_device_to_virtio_pci_proxy(vdev);
> +
> +    if (proxy != NULL) {
> +        memory_region_del_subregion(&proxy->notify.mr, mr);
> +    }
> +}
> +
>  static void virtio_pci_pre_plugged(DeviceState *d, Error **errp)
>  {
>      VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
> diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
> index 813082b0d7..8061133741 100644
> --- a/hw/virtio/virtio-pci.h
> +++ b/hw/virtio/virtio-pci.h
> @@ -213,6 +213,11 @@ static inline void virtio_pci_disable_modern(VirtIOPCIProxy *proxy)
>      proxy->disable_modern = true;
>  }
>  
> +bool virtio_pci_page_per_vq_enabled(VirtIODevice *vdev);
> +int virtio_pci_notify_region_map(VirtIODevice *vdev, int queue_idx,
> +                                 MemoryRegion *mr);
> +void virtio_pci_notify_region_unmap(VirtIODevice *vdev, MemoryRegion *mr);
> +
>  /*
>   * virtio-scsi-pci: This extends VirtioPCIProxy.
>   */

These are not great APIs unfortunately. Need to come up with generic names.
E.g. do we register and de-register host notifiers maybe?


> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 006d3d1148..90ee72984c 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -22,6 +22,7 @@
>  #include "qemu/atomic.h"
>  #include "hw/virtio/virtio-bus.h"
>  #include "hw/virtio/virtio-access.h"
> +#include "hw/virtio/virtio-pci.h"
>  #include "sysemu/dma.h"
>  
>  /*
> @@ -2681,6 +2682,44 @@ void virtio_device_release_ioeventfd(VirtIODevice *vdev)
>      virtio_bus_release_ioeventfd(vbus);
>  }
>  
> +bool virtio_device_parent_is_pci_device(VirtIODevice *vdev)
> +{
> +    BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> +    const char *typename = object_get_typename(OBJECT(qbus->parent));
> +
> +    return strstr(typename, "pci") != NULL;
> +}
> +
> +bool virtio_device_page_per_vq_enabled(VirtIODevice *vdev)
> +{
> +#ifdef CONFIG_VIRTIO_PCI
> +    if (virtio_device_parent_is_pci_device(vdev)) {
> +        return virtio_pci_page_per_vq_enabled(vdev);
> +    }
> +#endif
> +    return false;
> +}
> +

A better way to do this is to pass a callback to the bus where each bus can
implement its own.


> +int virtio_device_notify_region_map(VirtIODevice *vdev, int queue_idx,
> +                                    MemoryRegion *mr)
> +{
> +#ifdef CONFIG_VIRTIO_PCI
> +    if (virtio_device_parent_is_pci_device(vdev)) {
> +        return virtio_pci_notify_region_map(vdev, queue_idx, mr);
> +    }
> +#endif
> +    return -1;
> +}
> +
> +void virtio_device_notify_region_unmap(VirtIODevice *vdev, MemoryRegion *mr)
> +{
> +#ifdef CONFIG_VIRTIO_PCI
> +    if (virtio_device_parent_is_pci_device(vdev)) {
> +        virtio_pci_notify_region_unmap(vdev, mr);
> +    }
> +#endif
> +}
> +
>  static void virtio_device_class_init(ObjectClass *klass, void *data)
>  {
>      /* Set the default value here. */
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 098bdaaea3..b14accdb08 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -285,6 +285,11 @@ void virtio_device_stop_ioeventfd(VirtIODevice *vdev);
>  int virtio_device_grab_ioeventfd(VirtIODevice *vdev);
>  void virtio_device_release_ioeventfd(VirtIODevice *vdev);
>  bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev);
> +bool virtio_device_parent_is_pci_device(VirtIODevice *vdev);
> +bool virtio_device_page_per_vq_enabled(VirtIODevice *vdev);
> +int virtio_device_notify_region_map(VirtIODevice *vdev, int queue_idx,
> +                                    MemoryRegion *mr);
> +void virtio_device_notify_region_unmap(VirtIODevice *vdev, MemoryRegion *mr);
>  EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq);
>  void virtio_queue_host_notifier_read(EventNotifier *n);
>  void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx,
> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> index 41658060a7..2532c278ef 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -30,6 +30,7 @@
>  #include "config-host.h"
>  #ifdef NEED_CPU_H
>  #include "config-target.h"
> +#include "config-devices.h"
>  #else
>  #include "exec/poison.h"
>  #endif

This confuses me.
What does config-devices.h have to do with cpu.h?
And why do we want every single file in qemu to pull this in?

> diff --git a/scripts/create_config b/scripts/create_config
> index d727e5e36e..e4541a51ed 100755
> --- a/scripts/create_config
> +++ b/scripts/create_config
> @@ -58,6 +58,9 @@ case $line in
>      name=${line%=*}
>      echo "#define $name 1"
>      ;;
> + CONFIG_*='$(CONFIG_'*')') # configuration
> +    continue
> +    ;;

Can't figure out what this does. The comment does not help unfortunately.


>   CONFIG_*=*) # configuration
>      name=${line%=*}
>      value=${line#*=}
> -- 
> 2.11.0