Re: [PATCH v2] hw/acpi: limit warning on acpi table size to pc machines older than version 2.3

[Ani Sinha]

> On 06-Apr-2023, at 1:37 PM, Igor Mammedov <imammedo@redhat.com> wrote:
> 
> On Wed, 29 Mar 2023 10:27:26 +0530
> Ani Sinha <anisinha@redhat.com> wrote:
> 
>> 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>
> 
> Reviewed-by: Igor Mammedov <imammedo@redhat.com>

Michael, reminder to queue this for the next PR.

> 
>> ---
>> hw/i386/acpi-build.c | 6 ++++--
>> hw/i386/pc.c         | 1 +
>> hw/i386/pc_piix.c    | 1 +
>> include/hw/i386/pc.h | 3 +++
>> 4 files changed, 9 insertions(+), 2 deletions(-)
>> 
>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>> index b19fb4259e..91be76e61f 100644
>> --- a/hw/i386/acpi-build.c
>> +++ b/hw/i386/acpi-build.c
>> @@ -2616,7 +2616,8 @@ 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",
>> @@ -2627,7 +2628,8 @@ 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 7bebea57e3..2b66985013 100644
>> --- a/hw/i386/pc.c
>> +++ b/hw/i386/pc.c
>> @@ -1936,6 +1936,7 @@ 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 2f16011bab..8f7b3ae11b 100644
>> --- a/hw/i386/pc_piix.c
>> +++ b/hw/i386/pc_piix.c
>> @@ -745,6 +745,7 @@ 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 8206d5405a..6008eb045a 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"
>