Re: [qemu-s390x] [PATCH v1 0/8] MemoryDevice: introduce and use ResourceHandler

[David Hildenbrand]

On 03.05.2018 17:49, David Hildenbrand wrote:
> Hotplug handlers usually have the following tasks:
> 1. Allocate some resources for a new device
> 2. Make the new device visible for the guest
> 3. Notify the guest about the new device
> 
> Hotplug handlers have right now one limitation: They handle their own
> context and only care about resources they manage.
> 
> We can have devices that need certain other resources that are e.g.
> system resources managed by the machine. We need a clean way to assign
> these resources (without violating layers as brought up by Igor).
> 
> One example is virtio-mem/virtio-pmem. Both device types need to be
> assigned some region in guest physical address space. This device memory
> belongs to the machine and is managed by it. However, virito devices are
> hotplugged using the hotplug handler their proxy device implements. So we
> could trigger e.g. a PCI hotplug handler for virtio-pci or a CSS/CCW
> hotplug handler for virtio-ccw. But definetly not the machine.
> 
> So let's generalize the task of "assigning" resources and use it directly
> for memory devices. We now have a clean way to support any kind of memory
> device - independent of the underlying device type. Right now, only one
> resource handler per device can be supported (in addition to the existing
> hotplug handler).
> 
> You can find more details in patch nr 2.
> 
> This work is based on the already queued patch series
>     "[PATCH v4 00/11] pc-dimm: factor out MemoryDevice"
> 
> David Hildenbrand (8):
>   memory-device: always compile support for memory devices for SOFTMMU
>   qdev: introduce ResourceHandler as a first-stage hotplug handler
>   machine: provide default resource handler
>   memory-device: new functions to handle resource assignment
>   pc-dimm: implement new memory device functions
>   machine: introduce enforce_memory_device_align() and add it for pc
>   memory-device: factor out pre-assign into default resource handler
>   memory-device: factor out (un)assign into default resource handler
> 
>  hw/Makefile.objs               |   2 +-
>  hw/core/Makefile.objs          |   1 +
>  hw/core/machine.c              |  70 +++++++++++++++++++++++
>  hw/core/qdev.c                 |  41 +++++++++++++-
>  hw/core/resource-handler.c     |  57 +++++++++++++++++++
>  hw/i386/pc.c                   |  31 ++++++-----
>  hw/mem/Makefile.objs           |   2 +-
>  hw/mem/memory-device.c         | 122 
> +++++++++++++++++++++++++----------------
>  hw/mem/pc-dimm.c               |  53 ++++++++----------
>  hw/mem/trace-events            |   4 +-
>  hw/ppc/spapr.c                 |   5 +-
>  include/hw/boards.h            |  17 ++++++
>  include/hw/mem/memory-device.h |  17 ++++--
>  include/hw/mem/pc-dimm.h       |   3 +-
>  include/hw/resource-handler.h  |  46 ++++++++++++++++
>  stubs/Makefile.objs            |   1 -
>  stubs/qmp_memory_device.c      |  13 -----
>  17 files changed, 364 insertions(+), 121 deletions(-)
>  create mode 100644 hw/core/resource-handler.c
>  create mode 100644 include/hw/resource-handler.h
>  delete mode 100644 stubs/qmp_memory_device.c
> 

If there are no further comments, I'll send a v2 by the end of this
week. Thanks!

-- 

Thanks,

David / dhildenb