[PATCH v2 0/6] hw/acpi/viot: generate stable VIOT ACPI tables

[Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>]

I was working away at some improvements for PS2 devices when I noticed that one
small change to the instantiation of a PS2 mouse device caused a regression in
tests/qtest/bios-tables-test, specifically the /x86_64/acpi/q35/viot subtest.

Closer examination of the failed test output showed the problem was that the
order of the PCI host bridge entries had changed within the table causing the
generated binary to fail to match the version in tests/data/acpi/q35/VIOT.viot.

The error occurs because there is no guarantee in the order of PCI host bridges
being returned from object_child_foreach_recursive() used within
hw/acpi/viot.c's build_viot() function, so any change to the QOM tree can
potentially change the generated ACPI VIOT table ordering and cause the
regression tests to fail.

Fortunately the solution is fairly easy: change build_viot() to build an array
of PCI host bridges and then sort them first before generating the final ACPI
VIOT table. I've chosen to sort the PCI host bridges based upon the min_bus
number which seems to work okay here.

The changes in this patchset were heavily inspired by the build_iort() function
in hw/arm/virt-acpi-build.c which already does the right thing here. Patches 1-5
make the required changes before patch 6 updates the VIOT binary to match the
updated ACPI VIOT table ordering.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

v2:
- Rebase onto master
- Rename pci_host_bridges() to enumerate_pci_host_bridges() in patch 1
- Change return type of pci_host_range_compare() from int to gint in patch 5
- Tweak subject line in patch 5: s/PCI host bus/PCI host bridge/
- Add Acked-by and Reviewed-by tags from Ani


Mark Cave-Ayland (6):
  hw/acpi/viot: rename build_pci_range_node() to
    enumerate_pci_host_bridges()
  hw/acpi/viot: move the individual PCI host bridge entry generation to
    a new function
  hw/acpi/viot: build array of PCI host bridges before generating VIOT
    ACPI table
  tests/acpi: virt: allow VIOT acpi table changes
  hw/acpi/viot: sort VIOT ACPI table entries by PCI host bridge min_bus
  tests/acpi: virt: update golden masters for VIOT

 hw/acpi/viot.c                | 107 +++++++++++++++++++++-------------
 tests/data/acpi/q35/VIOT.viot | Bin 112 -> 112 bytes
 2 files changed, 68 insertions(+), 39 deletions(-)

-- 
2.20.1