acpi: Align the size to 128k

If table size is changed between virt_acpi_build and
virt_acpi_build_update, the table size would not be updated to
UEFI, therefore, just align the size to 128kb, which is enough
and same with x86. It would warn if 64k is not enough and the
align size should be updated.

Signed-off-by: Yubo Miao <miaoyubo@huawei.com>
Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
Message-Id: <20201119014841.7298-7-cenjiahui@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/arm/virt-acpi-build.c

@@ -57,6 +57,8 @@
 
 #define ARM_SPI_BASE 32
 
+#define ACPI_BUILD_TABLE_SIZE             0x20000
+
 static void acpi_dsdt_add_cpus(Aml *scope, int smp_cpus)
 {
     uint16_t i;
@@ -656,6 +658,15 @@ struct AcpiBuildState {
     bool patched;
 } AcpiBuildState;
 
+static void acpi_align_size(GArray *blob, unsigned align)
+{
+    /*
+     * Align size to multiple of given size. This reduces the chance
+     * we need to change size in the future (breaking cross version migration).
+     */
+    g_array_set_size(blob, ROUND_UP(acpi_data_len(blob), align));
+}
+
 static
 void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
 {
@@ -743,6 +754,20 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
         build_rsdp(tables->rsdp, tables->linker, &rsdp_data);
     }
 
+    /*
+     * The align size is 128, warn if 64k is not enough therefore
+     * the align size could be resized.
+     */
+    if (tables_blob->len > ACPI_BUILD_TABLE_SIZE / 2) {
+        warn_report("ACPI table size %u exceeds %d bytes,"
+                    " migration may not work",
+                    tables_blob->len, ACPI_BUILD_TABLE_SIZE / 2);
+        error_printf("Try removing CPUs, NUMA nodes, memory slots"
+                     " or PCI bridges.");
+    }
+    acpi_align_size(tables_blob, ACPI_BUILD_TABLE_SIZE);
+
+
     /* Cleanup memory that's no longer used. */
     g_array_free(table_offsets, true);
 }