[Qemu-devel] [RESEND RFC 0/6] AMD XGBE KVM platform passthrough

[Eric Auger <eric.auger@linaro.org>]

I am resending this RFC from Oct 12, after kernel 4.4-rc1 and
QEMU 2.5-rc1, hoping things have calmed down a little bit.

This RFC allows to set up AMD XGBE passthrough. This was tested on AMD
Seattle.

The first upstreamed device supporting KVM platform passthrough was the
Calxeda Midway XGMAC. Compared to this latter, the XGBE XGMAC exposes a
much more complex device tree node. Generating the device tree node for
the guest is the challenging and controversary part of this series.

- First There are 2 device tree node formats:
one where XGBE and PHY are described in separate nodes and another one
that combines both description in a single node (only supported by 4.2
onwards kernels). Only the combined description is supported for passthrough,
meaning the host must be >= 4.2 and must feature a device tree with a combined
description. The guest will also be exposed with a combined description,
meaning only >= 4.2 guest are supported. It is not planned to support
separate node representation since assignment of the PHY is less
straigtforward.

- the XGMAC/PHY node depends on 2 clock nodes (DMA and PTP).
The code checks those clocks are fixed to make sure they cannot be
switched off at some point after the native driver gets unbound.

- there are many property values to populate on guest side. Most of them
cannot be hardcoded. That series proposes a way to parse the host device
tree blob and retrieve host values to feed guest representation. Current
approach relies on dtc binary availability plus libfdt usage.
Other alternatives were discussed in:
http://www.spinics.net/lists/kvm-arm/msg16648.html.

- Currently host booted with ACPI is not supported.

The patches can be found at
https://git.linaro.org/people/eric.auger/qemu.git/shortlog/refs/heads/v2.4.0-xgbe-rfc

Best Regards

Eric


Eric Auger (6):
  hw/vfio/platform: amd-xgbe device
  device_tree: introduce load_device_tree_from_sysfs
  device_tree: introduce qemu_fdt_node_path
  device_tree: introduce qemu_fdt_getprop_optional
  hw/arm/sysbus-fdt: helpers for clock node generation
  hw/arm/sysbus-fdt: enable amd-xgbe dynamic instantiation

 device_tree.c                   |  97 ++++++++++++++
 hw/arm/sysbus-fdt.c             | 273 ++++++++++++++++++++++++++++++++++++++++
 hw/vfio/Makefile.objs           |   1 +
 hw/vfio/amd-xgbe.c              |  55 ++++++++
 include/hw/vfio/vfio-amd-xgbe.h |  51 ++++++++
 include/sysemu/device_tree.h    |   6 +
 6 files changed, 483 insertions(+)
 create mode 100644 hw/vfio/amd-xgbe.c
 create mode 100644 include/hw/vfio/vfio-amd-xgbe.h

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1.8.3.2