Re: [PATCH v2 3/4] hw/acpi: i386: bump MADT to revision 5

[Eric DeVolder <eric.devolder@oracle.com>]

On 4/19/23 09:56, Michael S. Tsirkin wrote:
> On Tue, Apr 18, 2023 at 12:52:18PM -0400, Eric DeVolder wrote:
>> Currently i386 QEMU generates MADT revision 3, and reports
>> MADT revision 1. ACPI 6.3 introduces MADT revision 5.
>>
>> For MADT revision 4, that introduces ARM GIC structures, which do
>> not apply to i386.
>>
>> For MADT revision 5, the Local APIC flags introduces the Online
>> Capable bitfield.
>>
>> Making MADT generate and report revision 5 will solve problems with
>> CPU hotplug (the Online Capable flag indicates hotpluggable CPUs).
>>
>> Link: https://lore.kernel.org/linux-acpi/20230327191026.3454-1-eric.devolder@oracle.com/T/#t
>> Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
>> ---
>>   hw/i386/acpi-common.c | 13 ++++++++++---
>>   1 file changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/i386/acpi-common.c b/hw/i386/acpi-common.c
>> index 52e5c1439a..286c1c5c32 100644
>> --- a/hw/i386/acpi-common.c
>> +++ b/hw/i386/acpi-common.c
>> @@ -38,8 +38,15 @@ void pc_madt_cpu_entry(int uid, const CPUArchIdList *apic_ids,
>>   {
>>       uint32_t apic_id = apic_ids->cpus[uid].arch_id;
>>       /* Flags – Local APIC Flags */
>> -    uint32_t flags = apic_ids->cpus[uid].cpu != NULL || force_enabled ?
>> -                     1 /* Enabled */ : 0;
>> +    bool enabled = apic_ids->cpus[uid].cpu != NULL || force_enabled ?
>> +                     true : false;
>> +    /*
>> +     * ACPI 6.3 5.2.12.2 Local APIC Flags: OnlineCapable must be 0
>> +     * if Enabled is set.
>> +     */
>> +    bool onlinecapable = enabled ? false : true;
> 
> Pls write this as onlinecapable = !enabled or just open-code on the next
> line - does not look like this variable adds  a lot of value.
> 
Will do!

>> +    uint32_t flags = onlinecapable ? 0x2 : 0x0 | /* Online Capable */
>> +                     enabled ? 0x1 : 0x0; /* Enabled */
>>   
>>       /* ACPI spec says that LAPIC entry for non present
>>        * CPU may be omitted from MADT or it must be marked
>> @@ -102,7 +109,7 @@ void acpi_build_madt(GArray *table_data, BIOSLinker *linker,
>>       MachineClass *mc = MACHINE_GET_CLASS(x86ms);
>>       const CPUArchIdList *apic_ids = mc->possible_cpu_arch_ids(MACHINE(x86ms));
>>       AcpiDeviceIfClass *adevc = ACPI_DEVICE_IF_GET_CLASS(adev);
>> -    AcpiTable table = { .sig = "APIC", .rev = 1, .oem_id = oem_id,
>> +    AcpiTable table = { .sig = "APIC", .rev = 5, .oem_id = oem_id,
>>                           .oem_table_id = oem_table_id };
>>   
>>       acpi_table_begin(&table, table_data);
>> -- 
>> 2.31.1
>