Re: [PATCH v2 6/6] hw/isa/piix: Resolve redundant TYPE_PIIX3_XEN_DEVICE

[Chuck Zmudzinski <brchuckz@xxxxxxx>]

On 1/4/23 1:48 PM, Philippe Mathieu-Daudé wrote:
> On 4/1/23 18:54, Chuck Zmudzinski wrote:
>> On 1/4/23 10:35 AM, Philippe Mathieu-Daudé wrote:
>>> +Markus/Thomas
>>>
>>> On 4/1/23 15:44, Bernhard Beschow wrote:
>>>> During the last patches, TYPE_PIIX3_XEN_DEVICE turned into a clone of
>>>> TYPE_PIIX3_DEVICE. Remove this redundancy.
>>>>
>>>> Signed-off-by: Bernhard Beschow <shentey@xxxxxxxxx>
>>>> ---
>>>>    hw/i386/pc_piix.c             |  4 +---
>>>>    hw/isa/piix.c                 | 20 --------------------
>>>>    include/hw/southbridge/piix.h |  1 -
>>>>    3 files changed, 1 insertion(+), 24 deletions(-)
>>>>
>>>> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
>>>> index 5738d9cdca..6b8de3d59d 100644
>>>> --- a/hw/i386/pc_piix.c
>>>> +++ b/hw/i386/pc_piix.c
>>>> @@ -235,8 +235,6 @@ static void pc_init1(MachineState *machine,
>>>>        if (pcmc->pci_enabled) {
>>>>            DeviceState *dev;
>>>>            PCIDevice *pci_dev;
>>>> -        const char *type = xen_enabled() ? TYPE_PIIX3_XEN_DEVICE
>>>> -                                         : TYPE_PIIX3_DEVICE;
>>>>            int i;
>>>>    
>>>>            pci_bus = i440fx_init(pci_type,
>>>> @@ -250,7 +248,7 @@ static void pc_init1(MachineState *machine,
>>>>                                           : pci_slot_get_pirq);
>>>>            pcms->bus = pci_bus;
>>>>    
>>>> -        pci_dev = pci_new_multifunction(-1, true, type);
>>>> +        pci_dev = pci_new_multifunction(-1, true, TYPE_PIIX3_DEVICE);
>>>>            object_property_set_bool(OBJECT(pci_dev), "has-usb",
>>>>                                     machine_usb(machine), &error_abort);
>>>>            object_property_set_bool(OBJECT(pci_dev), "has-acpi",
>>>> diff --git a/hw/isa/piix.c b/hw/isa/piix.c
>>>> index 98e9b12661..e4587352c9 100644
>>>> --- a/hw/isa/piix.c
>>>> +++ b/hw/isa/piix.c
>>>> @@ -33,7 +33,6 @@
>>>>    #include "hw/qdev-properties.h"
>>>>    #include "hw/ide/piix.h"
>>>>    #include "hw/isa/isa.h"
>>>> -#include "hw/xen/xen.h"
>>>>    #include "sysemu/runstate.h"
>>>>    #include "migration/vmstate.h"
>>>>    #include "hw/acpi/acpi_aml_interface.h"
>>>> @@ -465,24 +464,6 @@ static const TypeInfo piix3_info = {
>>>>        .class_init    = piix3_class_init,
>>>>    };
>>>>    
>>>> -static void piix3_xen_class_init(ObjectClass *klass, void *data)
>>>> -{
>>>> -    DeviceClass *dc = DEVICE_CLASS(klass);
>>>> -    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
>>>> -
>>>> -    k->realize = piix3_realize;
>>>> -    /* 82371SB PIIX3 PCI-to-ISA bridge (Step A1) */
>>>> -    k->device_id = PCI_DEVICE_ID_INTEL_82371SB_0;
>>>> -    dc->vmsd = &vmstate_piix3;
>>>
>>> IIUC, since this device is user-creatable, we can't simply remove it
>>> without going thru the deprecation process. Alternatively we could
>>> add a type alias:
>>>
>>> -- >8 --
>>> diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
>>> index 4b0ef65780..d94f7ea369 100644
>>> --- a/softmmu/qdev-monitor.c
>>> +++ b/softmmu/qdev-monitor.c
>>> @@ -64,6 +64,7 @@ typedef struct QDevAlias
>>>                                  QEMU_ARCH_LOONGARCH)
>>>    #define QEMU_ARCH_VIRTIO_CCW (QEMU_ARCH_S390X)
>>>    #define QEMU_ARCH_VIRTIO_MMIO (QEMU_ARCH_M68K)
>>> +#define QEMU_ARCH_XEN (QEMU_ARCH_ARM | QEMU_ARCH_I386)
>>>
>>>    /* Please keep this table sorted by typename. */
>>>    static const QDevAlias qdev_alias_table[] = {
>>> @@ -111,6 +112,7 @@ static const QDevAlias qdev_alias_table[] = {
>>>        { "virtio-tablet-device", "virtio-tablet", QEMU_ARCH_VIRTIO_MMIO },
>>>        { "virtio-tablet-ccw", "virtio-tablet", QEMU_ARCH_VIRTIO_CCW },
>>>        { "virtio-tablet-pci", "virtio-tablet", QEMU_ARCH_VIRTIO_PCI },
>>> +    { "PIIX3", "PIIX3-xen", QEMU_ARCH_XEN },
>> 
>> Hi Bernhard,
>> 
>> Can you comment if this should be:
>> 
>> +    { "PIIX", "PIIX3-xen", QEMU_ARCH_XEN },
>> 
>> instead? IIUC, the patch series also removed PIIX3 and PIIX4 and
>> replaced them with PIIX. Or am I not understanding correctly?
> 
> There is a confusion in QEMU between PCI bridges, the first PCI
> function they implement, and the other PCI functions.
> 
> Here TYPE_PIIX3_DEVICE means for "PCI function part of the PIIX
> south bridge chipset, which expose a PCI-to-ISA bridge". A better
> name could be TYPE_PIIX3_ISA_PCI_DEVICE. Unfortunately this
> device is named "PIIX3" with no indication of ISA bridge.


Thanks, you are right, I see the PIIX3 device still exists after
this patch set is applied.

chuckz@debian:~/sources-sid/qemu/qemu-7.50+dfsg/hw/i386$ grep -r PIIX3 *
pc_piix.c:        pci_dev = pci_new_multifunction(-1, true, TYPE_PIIX3_DEVICE);

I also understand there is the PCI-to-ISA bridge at 00:01.0 on the PCI bus:

chuckz@debian:~$ lspci
00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton II]
00:01.2 USB controller: Intel Corporation 82371SB PIIX3 USB [Natoma/Triton II] 
(rev 01)
00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
00:02.0 Unassigned class [ff80]: XenSource, Inc. Xen Platform Device (rev 01)
00:03.0 VGA compatible controller: Device 1234:1111 (rev 02)

I also see with this patch, there is a bridge that is a PIIX4 ACPI at 00:01.3.
I get the exact same output from lspci without the patch series, so that gives
me confidence it is working as designed.