Re: [PULL 5/5] m68k: add Virtual M68k Machine

[Philippe Mathieu-Daudé]

On 3/18/21 11:06 AM, Laurent Vivier wrote:
> Le 18/03/2021 à 11:02, Philippe Mathieu-Daudé a écrit :
>> On 3/18/21 10:52 AM, Laurent Vivier wrote:
>>> Le 18/03/2021 à 10:19, Philippe Mathieu-Daudé a écrit :
>>>> Hi Laurent,
>>>>
>>>> +Paolo / Thomas
>>>>
>>>> On 3/15/21 9:42 PM, Laurent Vivier wrote:
>>>>> The machine is based on Goldfish interfaces defined by Google
>>>>> for Android simulator. It uses Goldfish-rtc (timer and RTC),
>>>>> Goldfish-pic (PIC) and Goldfish-tty (for serial port and early tty).
>>>>>
>>>>> The machine is created with 128 virtio-mmio bus, and they can
>>>>> be used to use serial console, GPU, disk, NIC, HID, ...
>>>>>
>>>>> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
>>>>> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>>>>> Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>>>>> Message-Id: <20210312214145.2936082-6-laurent@vivier.eu>
>>>>> ---
>>>>>  default-configs/devices/m68k-softmmu.mak      |   1 +
>>>>>  .../standard-headers/asm-m68k/bootinfo-virt.h |  18 +
>>>>>  hw/m68k/virt.c                                | 313 ++++++++++++++++++
>>>>>  MAINTAINERS                                   |  13 +
>>>>>  hw/m68k/Kconfig                               |   9 +
>>>>>  hw/m68k/meson.build                           |   1 +
>>>>>  6 files changed, 355 insertions(+)
>>>>>  create mode 100644 include/standard-headers/asm-m68k/bootinfo-virt.h
>>>>>  create mode 100644 hw/m68k/virt.c
>>>>
>>>>> diff --git a/hw/m68k/Kconfig b/hw/m68k/Kconfig
>>>>> index 60d7bcfb8f2b..f839f8a03064 100644
>>>>> --- a/hw/m68k/Kconfig
>>>>> +++ b/hw/m68k/Kconfig
>>>>> @@ -23,3 +23,12 @@ config Q800
>>>>>      select ESP
>>>>>      select DP8393X
>>>>>      select OR_IRQ
>>>>> +
>>>>> +config M68K_VIRT
>>>>> +    bool
>>>>> +    select M68K_IRQC
>>>>> +    select VIRT_CTRL
>>>>> +    select GOLDFISH_PIC
>>>>> +    select GOLDFISH_TTY
>>>>> +    select GOLDFISH_RTC
>>>>> +    select VIRTIO_MMIO
>>>>
>>>> I had this error on gitlab:
>>>>
>>>> (qemu) QEMU_PROG: -drive driver=IMGFMT,file=TEST_DIR/t.IMGFMT,if=virtio:
>>>> 'virtio-blk-pci' is not a valid device model name
>>>> job: check-system-fedora
>>>> https://gitlab.com/philmd/qemu/-/jobs/1106469724
>>>>
>>>> I bisected locally to this commit.
>>>>
>>>> check-system-fedora uses build-system-fedora:
>>>>
>>>> build-system-fedora:
>>>>     CONFIGURE_ARGS: --disable-gcrypt --enable-nettle --enable-docs
>>>>              --enable-fdt=system --enable-slirp=system
>>>>              --enable-capstone=system
>>>>
>>>> I'm confused because the machine provides a VIRTIO bus
>>>> via MMIO:
>>>>
>>>> config VIRTIO_MMIO
>>>>     bool
>>>>     select VIRTIO
>>>>
>>>> I remember I tested your machine with virtio-blk-device.
>>>>
>>>> config VIRTIO_BLK
>>>>     bool
>>>>     default y
>>>>     depends on VIRTIO
>>>>
>>>> Ah, this is virtio-blk-pci, which has:
>>>>
>>>> virtio_pci_ss.add(when: 'CONFIG_VIRTIO_BLK', if_true:
>>>> files('virtio-blk-pci.c'))
>>>> virtio_ss.add_all(when: 'CONFIG_VIRTIO_PCI', if_true: virtio_pci_ss)
>>>>
>>>> And VIRTIO_PCI isn't selected...
>>>
>>> This machine doesn't have virtio-pci, but only virtio-mmio buses.
>>
>> Yes. I meant "VIRTIO_PCI isn't selected, which is the correct config
>> for this machine". So the problem isn't the m68k-virt machine addition,
>> but it shows another problem elsewhere.
>>
>>>> Are the tests incorrect then?
>>>>
>>>> libqos isn't restricted to PCI:
>>>>
>>>> tests/qtest/libqos/virtio-blk.c:24:#include "virtio-blk.h"
>>>> tests/qtest/libqos/virtio-blk.c:29:/* virtio-blk-device */
>>>> tests/qtest/libqos/virtio-blk.c:33:    if (!g_strcmp0(interface,
>>>> "virtio-blk")) {
>>>> tests/qtest/libqos/virtio-blk.c:40:    fprintf(stderr, "%s not present
>>>> in virtio-blk-device\n", interface);
>>>> tests/qtest/libqos/virtio-blk.c:109:    /* virtio-blk-device */
>>>> tests/qtest/libqos/virtio-blk.c:111:
>>>> qos_node_create_driver("virtio-blk-device", virtio_blk_device_create);
>>>> tests/qtest/libqos/virtio-blk.c:112:
>>>> qos_node_consumes("virtio-blk-device", "virtio-bus", &opts);
>>>> tests/qtest/libqos/virtio-blk.c:113:
>>>> qos_node_produces("virtio-blk-device", "virtio-blk");
>>>>
>>>> But qemu-iotests / qtests do use virtio-blk-pci. Maybe they should
>>>> use a generic virtio-blk-device instead, hoping it get plugged correctly
>>>> to the virtio bus...
>>>
>>> Yes, it's how the machine work: it has 128 virtio-mmio buses and 
>>> virtio-devices are plugged directly
>>> in the first free ones.
>>>
>>> I think the fix would be to disable the virtio-blk-pci test for the 
>>> machines without PCI bus.
>>>
>>> Why is it executed for now?
>>
>> This is probably the problem root cause.
>>
>> Possible fix:
>>
>> -->8 --
>> diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
>> index 66ee9fbf450..d7f3fad51c1 100644
>> --- a/tests/qtest/meson.build
>> +++ b/tests/qtest/meson.build
>> @@ -217,13 +217,17 @@
>>    'emc141x-test.c',
>>    'usb-hcd-ohci-test.c',
>>    'virtio-test.c',
>> -  'virtio-blk-test.c',
>> -  'virtio-net-test.c',
>> -  'virtio-rng-test.c',
>> -  'virtio-scsi-test.c',
>>    'virtio-serial-test.c',
>>    'vmxnet3-test.c',
>>  )
>> +if config_all_devices.has_key('CONFIG_VIRTIO_PCI')
>> +  qos_test_ss.add(
>> +    'virtio-blk-test.c',
>> +    'virtio-net-test.c',
>> +    'virtio-rng-test.c',
>> +    'virtio-scsi-test.c',
>> +  )
>> +endif
>>  if have_virtfs
>>    qos_test_ss.add(files('virtio-9p-test.c'))
>>  endif
>> ---
>>
>> I'll test that locally but not on Gitlab.

This approach doesn't work for the iotests.

> This also removes the virtio-devices test, I think we should keep the files, 
> but in the files to
> disable the PCI part when it is not available.
I don't understand how the virtio devices are created, it seems there
is an alias to generic virtio hw that map to the arch virtio bus.

I was not obvious to understand why start the virt machine with
"-device virtio-blk" returns "'virtio-blk-pci' is not a valid device
model name" at first, then I figured out the qdev_alias_table array.

Maybe you need to complete it for your arch? I've been using that:

-- >8 --
diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
index 8dc656becca..b326bd76c2a 100644
--- a/softmmu/qdev-monitor.c
+++ b/softmmu/qdev-monitor.c
@@ -65,8 +65,10 @@ static const QDevAlias qdev_alias_table[] = {
     { "virtio-balloon-ccw", "virtio-balloon", QEMU_ARCH_S390X },
     { "virtio-balloon-pci", "virtio-balloon",
             QEMU_ARCH_ALL & ~QEMU_ARCH_S390X },
+    { "virtio-blk-device", "virtio-blk", QEMU_ARCH_M68K },
     { "virtio-blk-ccw", "virtio-blk", QEMU_ARCH_S390X },
-    { "virtio-blk-pci", "virtio-blk", QEMU_ARCH_ALL & ~QEMU_ARCH_S390X },
+    { "virtio-blk-pci", "virtio-blk", QEMU_ARCH_ALL
+                                      & ~(QEMU_ARCH_S390X |
QEMU_ARCH_M68K) },
     { "virtio-gpu-ccw", "virtio-gpu", QEMU_ARCH_S390X },
     { "virtio-gpu-pci", "virtio-gpu", QEMU_ARCH_ALL & ~QEMU_ARCH_S390X },
     { "virtio-input-host-ccw", "virtio-input-host", QEMU_ARCH_S390X },
@@ -84,8 +86,10 @@ static const QDevAlias qdev_alias_table[] = {
     { "virtio-rng-pci", "virtio-rng", QEMU_ARCH_ALL & ~QEMU_ARCH_S390X },
     { "virtio-scsi-ccw", "virtio-scsi", QEMU_ARCH_S390X },
     { "virtio-scsi-pci", "virtio-scsi", QEMU_ARCH_ALL & ~QEMU_ARCH_S390X },
+    { "virtio-serial-device", "virtio-serial", QEMU_ARCH_M68K },
     { "virtio-serial-ccw", "virtio-serial", QEMU_ARCH_S390X },
-    { "virtio-serial-pci", "virtio-serial", QEMU_ARCH_ALL &
~QEMU_ARCH_S390X },
+    { "virtio-serial-pci", "virtio-serial", QEMU_ARCH_ALL
+                                            & ~(QEMU_ARCH_S390X |
QEMU_ARCH_M68K)},
     { "virtio-tablet-ccw", "virtio-tablet", QEMU_ARCH_S390X },
     { "virtio-tablet-pci", "virtio-tablet", QEMU_ARCH_ALL &
~QEMU_ARCH_S390X },
     { }
---

But this looks ugly, I don't think it should work that way (because
a machine could provide virtio buses over multiple transport, mmio
and pci...).

I'll ignore this problem and send my pull request with a red CI
as others seem to do.

Regards,

Phil.