hw/acpi: limit warning on acpi table size to pc machines older than version 2.3

i440fx machine versions 2.3 and newer supports dynamic ram
resizing. See commit a1666142db6233 ("acpi-build: make ROMs RAM blocks resizeable") .
Currently supported all q35 machine types (versions 2.4 and newer) supports
resizable RAM/ROM blocks.Therefore the warning generated when the ACPI table
size exceeds a pre-defined value does not apply to those machine versions.
Add a check limiting the warning message to only those machines that does not
support expandable ram blocks (that is, i440fx machines with version 2.2
and older).

Signed-off-by: Ani Sinha <anisinha@redhat.com>
Message-Id: <20230329045726.14028-1-anisinha@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

4 files changed, 9 insertions, 2 deletions

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 7f211e1f48..512162003b 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -2697,7 +2697,8 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
         int legacy_table_size =
             ROUND_UP(tables_blob->len - aml_len + legacy_aml_len,
                      ACPI_BUILD_ALIGN_SIZE);
-        if (tables_blob->len > legacy_table_size) {
+        if ((tables_blob->len > legacy_table_size) &&
+            !pcmc->resizable_acpi_blob) {
             /* Should happen only with PCI bridges and -M pc-i440fx-2.0.  */
             warn_report("ACPI table size %u exceeds %d bytes,"
                         " migration may not work",
@@ -2708,7 +2709,8 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
         g_array_set_size(tables_blob, legacy_table_size);
     } else {
         /* Make sure we have a buffer in case we need to resize the tables. */
-        if (tables_blob->len > ACPI_BUILD_TABLE_SIZE / 2) {
+        if ((tables_blob->len > ACPI_BUILD_TABLE_SIZE / 2) &&
+            !pcmc->resizable_acpi_blob) {
             /* As of QEMU 2.1, this fires with 160 VCPUs and 255 memory slots.  */
             warn_report("ACPI table size %u exceeds %d bytes,"
                         " migration may not work",
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 615e1d3d06..d761c8c775 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1946,6 +1946,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     pcmc->acpi_data_size = 0x20000 + 0x8000;
     pcmc->pvh_enabled = true;
     pcmc->kvmclock_create_always = true;
+    pcmc->resizable_acpi_blob = true;
     assert(!mc->get_hotplug_handler);
     mc->get_hotplug_handler = pc_get_hotplug_handler;
     mc->hotplug_allowed = pc_hotplug_allowed;
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 21591dad8d..66a849d279 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -756,6 +756,7 @@ static void pc_i440fx_2_2_machine_options(MachineClass *m)
     compat_props_add(m->compat_props, hw_compat_2_2, hw_compat_2_2_len);
     compat_props_add(m->compat_props, pc_compat_2_2, pc_compat_2_2_len);
     pcmc->rsdp_in_ram = false;
+    pcmc->resizable_acpi_blob = false;
 }
 
 DEFINE_I440FX_MACHINE(v2_2, "pc-i440fx-2.2", pc_compat_2_2_fn,
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index eb668e9034..84935fc958 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -127,6 +127,9 @@ struct PCMachineClass {
 
     /* create kvmclock device even when KVM PV features are not exposed */
     bool kvmclock_create_always;
+
+    /* resizable acpi blob compat */
+    bool resizable_acpi_blob;
 };
 
 #define TYPE_PC_MACHINE "generic-pc-machine"