hw/acpi/viot: sort VIOT ACPI table entries by PCI host bridge min_bus

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>
Reviewed-by: Ani Sinha <ani@anisinha.ca>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220525173232.31429-6-mark.cave-ayland@ilande.co.uk>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/acpi/viot.c b/hw/acpi/viot.c
index c32bbdd180246c3c2cadd5300feeb681abd81a8b..4e0bf6906738f6b29991944c3479cb27b1bb87ab 100644 (file)
--- a/hw/acpi/viot.c
+++ b/hw/acpi/viot.c
@@ -64,6 +64,20 @@ static int enumerate_pci_host_bridges(Object *obj, void *opaque)
     return 0;
 }
 
+static gint pci_host_range_compare(gconstpointer a, gconstpointer b)
+{
+    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), enumerate_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 */