pc: acpi-build: migrate RSDP table

Makes sure that RSDP stays the same
/i.e. matches ACPI tables blob in source/
if guest is migrated during RSDP reading or
has been already shadowed by firmware.

Fix applies only to new machine types starting
from 2.3, so it won't break migration for old
machine types.
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NMarcel Apfelbaum <marcel@redhat.com>

hw/i386/acpi-build.c

@@ -1651,15 +1651,21 @@ void acpi_setup(PcGuestInfo *guest_info)
     fw_cfg_add_file(guest_info->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
                     tables.tcpalog->data, acpi_data_len(tables.tcpalog));
 
-    /*
-     * Though RSDP is small, its contents isn't immutable, so
-     * update it along with the rest of tables on guest access.
-     */
-    fw_cfg_add_file_callback(guest_info->fw_cfg, ACPI_BUILD_RSDP_FILE,
-                             acpi_build_update, build_state,
-                             tables.rsdp->data, acpi_data_len(tables.rsdp));
-
-    build_state->rsdp = tables.rsdp->data;
+    if (guest_info->has_immutable_rsdp) {
+        /*
+         * Keep for compatibility with old machine types.
+         * Though RSDP is small, its contents isn't immutable, so
+         * update it along with the rest of tables on guest access.
+         */
+        fw_cfg_add_file_callback(guest_info->fw_cfg, ACPI_BUILD_RSDP_FILE,
+                                 acpi_build_update, build_state,
+                                 tables.rsdp->data, acpi_data_len(tables.rsdp));
+        build_state->rsdp = tables.rsdp->data;
+    } else {
+        build_state->rsdp = qemu_get_ram_ptr(
+            acpi_add_rom_blob(build_state, tables.rsdp, ACPI_BUILD_RSDP_FILE, 0)
+        );
+    }
 
     qemu_register_reset(acpi_build_reset, build_state);
     acpi_build_reset(build_state);

hw/i386/pc_piix.c

@@ -60,6 +60,7 @@ static const int ide_iobase2[MAX_IDE_BUS] = { 0x3f6, 0x376 };
 static const int ide_irq[MAX_IDE_BUS] = { 14, 15 };
 
 static bool has_acpi_build = true;
+static bool has_immutable_rsdp;
 static int legacy_acpi_table_size;
 static bool smbios_defaults = true;
 static bool smbios_legacy_mode;
@@ -168,6 +169,7 @@ static void pc_init1(MachineState *machine,
 
     guest_info->isapc_ram_fw = !pci_enabled;
     guest_info->has_reserved_memory = has_reserved_memory;
+    guest_info->has_immutable_rsdp = has_immutable_rsdp;
 
     if (smbios_defaults) {
         MachineClass *mc = MACHINE_GET_CLASS(machine);
@@ -310,6 +312,7 @@ static void pc_init_pci(MachineState *machine)
 
 static void pc_compat_2_2(MachineState *machine)
 {
+    has_immutable_rsdp = true;
     x86_cpu_compat_set_features("kvm64", FEAT_1_EDX, 0, CPUID_VME);
     x86_cpu_compat_set_features("kvm32", FEAT_1_EDX, 0, CPUID_VME);
     x86_cpu_compat_set_features("Conroe", FEAT_1_EDX, 0, CPUID_VME);

hw/i386/pc_q35.c

@@ -50,6 +50,7 @@
 #define MAX_SATA_PORTS     6
 
 static bool has_acpi_build = true;
+static bool has_immutable_rsdp;
 static bool smbios_defaults = true;
 static bool smbios_legacy_mode;
 static bool smbios_uuid_encoded = true;
@@ -154,6 +155,7 @@ static void pc_q35_init(MachineState *machine)
     guest_info->isapc_ram_fw = false;
     guest_info->has_acpi_build = has_acpi_build;
     guest_info->has_reserved_memory = has_reserved_memory;
+    guest_info->has_immutable_rsdp = has_immutable_rsdp;
 
     /* Migration was not supported in 2.0 for Q35, so do not bother
      * with this hack (see hw/i386/acpi-build.c).
@@ -289,6 +291,7 @@ static void pc_q35_init(MachineState *machine)
 
 static void pc_compat_2_2(MachineState *machine)
 {
+    has_immutable_rsdp = true;
     x86_cpu_compat_set_features("kvm64", FEAT_1_EDX, 0, CPUID_VME);
     x86_cpu_compat_set_features("kvm32", FEAT_1_EDX, 0, CPUID_VME);
     x86_cpu_compat_set_features("Conroe", FEAT_1_EDX, 0, CPUID_VME);

include/hw/i386/pc.h

@@ -104,6 +104,7 @@ struct PcGuestInfo {
     int legacy_acpi_table_size;
     bool has_acpi_build;
     bool has_reserved_memory;
+    bool has_immutable_rsdp;
 };
 
 /* parallel.c */