VFIO mdev aggregated resources handling

Hi,

This is a refresh on previous series: https://patchwork.kernel.org/cover/11208279/
and https://patchwork.freedesktop.org/series/70425/

Current mdev device create interface depends on fixed mdev type, which get uuid from user to create instance of mdev device. If user wants to use customized number of resource for mdev device, then only can create new mdev type for that which may not be flexible. This requirement comes not only from to be able to allocate flexible resources for KVMGT, but also from Intel scalable IO virtualization which would use vfio/mdev to be able to allocate arbitrary resources on mdev instance. More info on [1] [2] [3].

As we agreed that for current opaque mdev device type, we'd still explore management interface based on mdev sysfs definition. And this one tries to follow Alex's previous suggestion to create generic parameters under 'mdev' directory for each device, so vendor driver could provide support like as other defined mdev sysfs entries.

For mdev type with aggregation support, files as "aggregated_instances" and "max_aggregation" should be created under 'mdev' directory. E.g

/sys/devices/pci0000:00/0000:00:02.0/<UUID>/mdev/
|-- aggregated_instances
|-- max_aggregation

"aggregated_instances" is used to set or return current number of instances for aggregation, which can not be larger than "max_aggregation".

The first patch is to update the document for new mdev parameter directory. The second one is to add aggregation support in GVT driver.

References:
[1] https://software.intel.com/en-us/download/intel-virtualization-technology-for-directed-io-architecture-specification
[2] https://software.intel.com/en-us/download/intel-scalable-io-virtualization-technical-specification
[3] https://schd.ws/hosted_files/lc32018/00/LC3-SIOV-final.pdf

Changelog:
v3:
- add more description for sysfs entries
- rebase GVT support
- rename accounting function

Zhenyu Wang (2):
Documentation/driver-api/vfio-mediated-device.rst: update for
aggregation support
drm/i915/gvt: mdev aggregation type

 .../driver-api/vfio-mediated-device.rst       |  22 +++
 drivers/gpu/drm/i915/gvt/aperture_gm.c        |  44 +++--
 drivers/gpu/drm/i915/gvt/gtt.c                |   9 +-
 drivers/gpu/drm/i915/gvt/gvt.c                |   7 +-
 drivers/gpu/drm/i915/gvt/gvt.h                |  42 +++--
 drivers/gpu/drm/i915/gvt/kvmgt.c              | 115 +++++++++++-
 drivers/gpu/drm/i915/gvt/vgpu.c               | 172 ++++++++++++------
 7 files changed, 317 insertions(+), 94 deletions(-)

2.25.1