Re: [Qemu-devel] [PATCH v2 14/20] memory-device: ids of virtio based devices are special

[Dr. David Alan Gilbert]

Actually on second thoughts, a question:

* David Hildenbrand (address@hidden) wrote:
> When reporting the id of virtio-based memory devices, we always have to
> take the one of the proxy device (parent).
> 
> Expose the function, so especially virtio-based memory devices can
> reuse the function when filling out the id in MemoryDeviceInfo.
> 
> Details:
> 
> When the user creates a virtio device (e.g.  virtio-balloon-pci), two
> devices are actually created.
> 
> 1. Virtio proxy device (e.g. TYPE_VIRTIO_BALLOON_PCI)
> 2. The "real" virtio device (e.g. TYPE_VIRTIO_BALLOON).
> 
> 1. aliases all properties of 2, so 2. can be properly configured using 1.
> 1. gets the device ID set specified by the user. 2. gets no ID set.
> 
> If we want to make 2. a MemoryDevice but report errors/information to the
> user, we always have to report the id of 1. (because that's the device the
> user instantiated and configured).
> 
> Signed-off-by: David Hildenbrand <address@hidden>
> ---
>  hw/mem/memory-device.c         | 21 +++++++++++++++++++--
>  include/hw/mem/memory-device.h |  1 +
>  2 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
> index a31ba73ea7..89a0c584be 100644
> --- a/hw/mem/memory-device.c
> +++ b/hw/mem/memory-device.c
> @@ -19,6 +19,22 @@
>  #include "sysemu/kvm.h"
>  #include "trace.h"
>  
> +const char *memory_device_id(const MemoryDeviceState *md)
> +{
> +    Object *obj = OBJECT(md);
> +
> +    /* always use the ID of the proxy device for virtio devices */
> +    if (object_dynamic_cast(obj, TYPE_VIRTIO_DEVICE)) {
> +        if (obj->parent && object_dynamic_cast(obj->parent, TYPE_DEVICE)) {
> +            const DeviceState *parent_dev = DEVICE(obj->parent);
> +
> +            return parent_dev->id;
> +        }
> +        return NULL;
> +    }
> +    return DEVICE(md)->id;
> +}
> +
>  static gint memory_device_addr_sort(gconstpointer a, gconstpointer b)
>  {
>      const MemoryDeviceState *md_a = MEMORY_DEVICE(a);
> @@ -168,6 +184,7 @@ static uint64_t memory_device_get_free_addr(MachineState 
> *ms,
>      for (item = list; item; item = g_slist_next(item)) {
>          MemoryDeviceState *md = item->data;
>          const MemoryDeviceClass *mdc = MEMORY_DEVICE_GET_CLASS(OBJECT(md));
> +        const char *id = memory_device_id(md);
>          uint64_t md_size, md_addr;
>  
>          md_addr = mdc->get_addr(md);
> @@ -178,8 +195,8 @@ static uint64_t memory_device_get_free_addr(MachineState 
> *ms,
>  
>          if (ranges_overlap(md_addr, md_size, new_addr, size)) {
>              if (hint) {
> -                const DeviceState *d = DEVICE(md);
> -                error_setg(errp, "address range conflicts with '%s'", d->id);
> +                error_setg(errp, "address range conflicts with '%s'",
> +                           id ? id : 0);

What's that 'id ? id : 0' trick for?

Dave

>                  goto out;
>              }
>              new_addr = QEMU_ALIGN_UP(md_addr + md_size, align);
> diff --git a/include/hw/mem/memory-device.h b/include/hw/mem/memory-device.h
> index 05cb9437b7..324cc45b6f 100644
> --- a/include/hw/mem/memory-device.h
> +++ b/include/hw/mem/memory-device.h
> @@ -54,6 +54,7 @@ typedef struct MemoryDeviceClass {
>                               MemoryDeviceInfo *info);
>  } MemoryDeviceClass;
>  
> +const char *memory_device_id(const MemoryDeviceState *md);
>  MemoryDeviceInfoList *qmp_memory_device_list(void);
>  uint64_t get_plugged_memory_size(void);
>  void memory_device_pre_plug(MemoryDeviceState *md, MachineState *ms,
> -- 
> 2.17.1
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK