Re: [PATCH 5/6] hw/acpi/viot: sort VIOT ACPI table entries by PCI host bus min_bus

[Ani Sinha <ani@anisinha.ca>]

On Wed, May 18, 2022 at 4:39 PM Mark Cave-Ayland
<mark.cave-ayland@ilande.co.uk> wrote:
>
> This ensures that the VIOT ACPI table output is always stable for a given PCI
> topology by ensuring that entries are ordered according to min_bus.
>
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
other than the nit below,
Reviewed-by: Ani Sinha <ani@anisinha.ca>

> ---
>  hw/acpi/viot.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>
> diff --git a/hw/acpi/viot.c b/hw/acpi/viot.c
> index ce3b7b8c75..f5714b95bd 100644
> --- a/hw/acpi/viot.c
> +++ b/hw/acpi/viot.c
> @@ -64,6 +64,20 @@ static int pci_host_bridges(Object *obj, void *opaque)
>      return 0;
>  }
>
> +static int pci_host_range_compare(gconstpointer a, gconstpointer b)

nit: shouldn't this have a gint return type since we use gconstpointer
as arguments anyway?
https://docs.gtk.org/glib/callback.CompareFunc.html

> +{
> +    struct viot_pci_host_range *range_a = (struct viot_pci_host_range *)a;
> +    struct viot_pci_host_range *range_b = (struct viot_pci_host_range *)b;
> +
> +    if (range_a->min_bus < range_b->min_bus) {
> +        return -1;
> +    } else if (range_a->min_bus > range_b->min_bus) {
> +        return 1;
> +    } else {
> +        return 0;
> +    }
> +}
> +
>  /*
>   * Generate a VIOT table with one PCI-based virtio-iommu that manages PCI
>   * endpoints.
> @@ -87,6 +101,9 @@ void build_viot(MachineState *ms, GArray *table_data, BIOSLinker *linker,
>      object_child_foreach_recursive(OBJECT(ms), pci_host_bridges,
>                                     pci_host_ranges);
>
> +    /* Sort the pci host ranges by min_bus */
> +    g_array_sort(pci_host_ranges, pci_host_range_compare);
> +
>      /* ACPI table header */
>      acpi_table_begin(&table, table_data);
>      /* Node count */
> --
> 2.20.1
>