hw/acpi/viot: build array of PCI host bridges before generating VIOT ACPI table

Perform the generation of the VIOT ACPI table in 2 separate passes: the first pass
enumerates all of the PCI host bridges and adds the min_bus and max_bus information
to an array.

Once this is done the VIOT table header is generated using the size of the array
to calculate the node count, which means it is no longer necessary to use a
sub-array to hold the PCI host bridge range information along with viommu_off.

Finally the PCI host bridge array is iterated again to add the required entries
to the final VIOT ACPI table.

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: <20220525173232.31429-4-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>

1 files changed, 24 insertions, 18 deletions

diff --git a/hw/acpi/viot.c b/hw/acpi/viot.c
index 5dafcbf5ef..c32bbdd180 100644
--- a/hw/acpi/viot.c
+++ b/hw/acpi/viot.c
@@ -10,10 +10,9 @@
 #include "hw/pci/pci.h"
 #include "hw/pci/pci_host.h"
 
-struct viot_pci_ranges {
-    GArray *blob;
-    size_t count;
-    uint16_t output_node;
+struct viot_pci_host_range {
+    int min_bus;
+    int max_bus;
 };
 
 static void build_pci_host_range(GArray *table_data, int min_bus, int max_bus,
@@ -44,8 +43,7 @@ static void build_pci_host_range(GArray *table_data, int min_bus, int max_bus,
 /* Build PCI range for a given PCI host bridge */
 static int enumerate_pci_host_bridges(Object *obj, void *opaque)
 {
-    struct viot_pci_ranges *pci_ranges = opaque;
-    GArray *blob = pci_ranges->blob;
+    GArray *pci_host_ranges = opaque;
 
     if (object_dynamic_cast(obj, TYPE_PCI_HOST_BRIDGE)) {
         PCIBus *bus = PCI_HOST_BRIDGE(obj)->bus;
@@ -55,9 +53,11 @@ static int enumerate_pci_host_bridges(Object *obj, void *opaque)
 
             pci_bus_range(bus, &min_bus, &max_bus);
 
-            build_pci_host_range(blob, min_bus, max_bus,
-                                 pci_ranges->output_node);
-            pci_ranges->count++;
+            const struct viot_pci_host_range pci_host_range = {
+                .min_bus = min_bus,
+                .max_bus = max_bus,
+            };
+            g_array_append_val(pci_host_ranges, pci_host_range);
         }
     }
 
@@ -78,19 +78,19 @@ void build_viot(MachineState *ms, GArray *table_data, BIOSLinker *linker,
     int viommu_off = 48;
     AcpiTable table = { .sig = "VIOT", .rev = 0,
                         .oem_id = oem_id, .oem_table_id = oem_table_id };
-    struct viot_pci_ranges pci_ranges = {
-        .output_node = viommu_off,
-        .blob = g_array_new(false, true /* clear */, 1),
-    };
+    GArray *pci_host_ranges =  g_array_new(false, true,
+                                           sizeof(struct viot_pci_host_range));
+    struct viot_pci_host_range *pci_host_range;
+    int i;
 
     /* Build the list of PCI ranges that this viommu manages */
     object_child_foreach_recursive(OBJECT(ms), enumerate_pci_host_bridges,
-                                   &pci_ranges);
+                                   pci_host_ranges);
 
     /* ACPI table header */
     acpi_table_begin(&table, table_data);
     /* Node count */
-    build_append_int_noprefix(table_data, pci_ranges.count + 1, 2);
+    build_append_int_noprefix(table_data, pci_host_ranges->len + 1, 2);
     /* Node offset */
     build_append_int_noprefix(table_data, viommu_off, 2);
     /* Reserved */
@@ -111,9 +111,15 @@ void build_viot(MachineState *ms, GArray *table_data, BIOSLinker *linker,
     build_append_int_noprefix(table_data, 0, 8);
 
     /* PCI ranges found above */
-    g_array_append_vals(table_data, pci_ranges.blob->data,
-                        pci_ranges.blob->len);
-    g_array_free(pci_ranges.blob, true);
+    for (i = 0; i < pci_host_ranges->len; i++) {
+        pci_host_range = &g_array_index(pci_host_ranges,
+                                        struct viot_pci_host_range, i);
+
+        build_pci_host_range(table_data, pci_host_range->min_bus,
+                             pci_host_range->max_bus, viommu_off);
+    }
+
+    g_array_free(pci_host_ranges, true);
 
     acpi_table_end(linker, &table);
 }