Re: [Qemu-devel] [PATCH] hw/pci: disable pci-bridge's shpc by default

[Marcel Apfelbaum <marcel@redhat.com>]

On 11/22/2016 10:25 PM, Laurent Vivier wrote:
>
>
> On 22/11/2016 18:26, Marcel Apfelbaum wrote:
>> On 11/18/2016 05:52 PM, Andrew Jones wrote:
>>> On Wed, Nov 16, 2016 at 07:05:25PM +0200, Marcel Apfelbaum wrote:
>>>> On 11/16/2016 06:44 PM, Andrew Jones wrote:
>>>>> On Sat, Nov 05, 2016 at 06:46:34PM +0200, Marcel Apfelbaum wrote:
>>>>>> On 11/03/2016 09:40 PM, Michael S. Tsirkin wrote:
>>>>>>> On Thu, Nov 03, 2016 at 01:05:44PM +0200, Marcel Apfelbaum wrote:
>>>>>>>> On 11/03/2016 06:18 AM, Michael S. Tsirkin wrote:
>>>>>>>>> On Wed, Nov 02, 2016 at 05:16:42PM +0200, Marcel Apfelbaum wrote:
>>>>>>>>>> The shpc component is optional while  ACPI hotplug is used
>>>>>>>>>> for hot-plugging PCI devices into a PCI-PCI bridge.
>>>>>>>>>> Disabling the shpc by default will make slot 0 usable at boot time
>>>>>>>>
>>>>>>>> Hi Michael
>>>>>>>>
>>>>>>>>>
>>>>>>>>> at the cost of breaking all hotplug for all non-acpi users.
>>>>>>>>>
>>>>>>>>
>>>>>>>> Do we have a non-acpi user that is able to use the shpc component
>>>>>>>> as-is today?
>>>>>>>
>>>>>>> power and some arm systems I guess?
>>>>>>>
>>>>>>
>>>>>> Adding Andrew , maybe he can give us an answer.
>>>>>
>>>>> Not really :-) My lack of PCI knowledge makes that difficult. I'd be
>>>>> happy
>>>>> to help with an experiment though. Can you give me command line
>>>>> arguments,
>>>>> qmp commands, etc. that I should use to try it out? I imagine I should
>>>>> just boot an ARM guest using DT (instead of ACPI) and then attempt to
>>>>> hotplug a PCI device. I'm not sure, however, what, if any, special
>>>>> configuration I need in order to ensure I'm testing what you're
>>>>> interested in.
>>>>>
>>>>
>>>> Hi Drew,
>>>>
>>>>
>>>> Just run QEMU with '-device pci-bridge,chassis_nr=1,id=bridge1
>>>> -monitor stdio'
>>>> with an ARM guest using DT and wait until the guest finish booting.
>>>>
>>>> Then run at hmp:
>>>> device_add virtio-net-pci,bus=bridge1,id=net2
>>>>
>>>> Next run lspci in the guest to see the new device.
>>>
>>> Thanks for the instructions Marcel. Here's the results
>>>
>>>  $QEMU -machine virt,accel=$ACCEL -cpu $CPU -nographic -m 4096 -smp 8 \
>>>        -bios /usr/share/AAVMF/AAVMF_CODE.fd \
>>>        -device pci-bridge,chassis_nr=1,id=bridge1 \
>>>        -drive file=$FEDORA_IMG,if=none,id=dr0,format=qcow2 \
>>>        -device virtio-blk-pci,bus=bridge1,addr=01,drive=dr0,id=disk0 \
>>>        -netdev user,id=hostnet0 \
>>>        -device virtio-net-pci,bus=bridge1,addr=02,netdev=hostnet0,id=net0
>>>
>>>  # lspci
>>>  00:00.0 Host bridge: Red Hat, Inc. Device 0008
>>>  00:01.0 PCI bridge: Red Hat, Inc. QEMU PCI-PCI bridge
>>>  01:01.0 SCSI storage controller: Red Hat, Inc Virtio block device
>>>  01:02.0 Ethernet controller: Red Hat, Inc Virtio network device
>>>
>>>  (qemu) device_add virtio-net-pci,bus=bridge1,id=net2
>>>  Unsupported PCI slot 0 for standard hotplug controller. Valid slots are
>>>  between 1 and 31.
>>>
>>> (Tried again giving addr=03)
>>>
>>>  (qemu) device_add virtio-net-pci,bus=bridge1,id=net2,addr=03
>>>
>>> (Seemed to work, but...)
>>>
>>>  # lspci
>>>  00:00.0 Host bridge: Red Hat, Inc. Device 0008
>>>  00:01.0 PCI bridge: Red Hat, Inc. QEMU PCI-PCI bridge
>>>  01:01.0 SCSI storage controller: Red Hat, Inc Virtio block device
>>>  01:02.0 Ethernet controller: Red Hat, Inc Virtio network device
>>>
>>> (Doesn't show up in lscpi. So I guess it doesn't work)
>>>
>>
>> Hi Drew,
>> Thanks for confirming that it doesn't work.
>>
>> Michael asked if we can check the same for powerpc before
>> disabling the shpc by default.
>>
>> Adding David, Thomas and Laurrent, maybe they have time
>> to check it for powerpc.
>
> With this patch:
>
> # lspci
> 00:00.0 PCI bridge: Red Hat, Inc. QEMU PCI-PCI bridge
> 00:03.0 Unclassified device [00ff]: Red Hat, Inc Virtio memory balloon
> [root@dhcp6-56 ~]# QEMU 2.7.90 monitor - type 'help' for more information
> (qemu) device_add virtio-net-pci,bus=bridge1,id=net2
> Bus 'bridge1' does not support hotplugging
> (qemu) device_add virtio-net-pci,bus=bridge1,id=net2,addr=3
> Bus 'bridge1' does not support hotplugging
>
> Without this patch:
>
> # lspci
> 00:00.0 PCI bridge: Red Hat, Inc. QEMU PCI-PCI bridge
> 00:03.0 Unclassified device [00ff]: Red Hat, Inc Virtio memory balloon
> [root@dhcp6-56 ~]# QEMU 2.7.90 monitor - type 'help' for more information
> (qemu) device_add virtio-net-pci,bus=bridge1,id=net2
> Unsupported PCI slot 0 for standard hotplug controller. Valid slots are
> between 1 and 31.
> (qemu) device_add virtio-net-pci,bus=bridge1,id=net2,addr=3
> (qemu) [   37.342908] shpchp 0000:00:00.0: Latch close on Slot(3)
> [   37.342963] shpchp 0000:00:00.0: Button pressed on Slot(3)
> [   37.343003] shpchp 0000:00:00.0: Card present on Slot(3)
> [   37.344186] shpchp 0000:00:00.0: PCI slot #3 - powering on due to
> button press
> [   43.361827] shpchp 0000:00:00.0: No new device found


Hi Laurrent,
Thank you for the fast reply!

What I see from the log is that ppc does use the shpc for hotplug,
but there is some implementation bug preventing it to work.

Drew, may I trouble one last time for the dmesg?
I think we would see exactly the same log.


Thanks,
Marcel

> [   43.361867] shpchp 0000:00:00.0: Cannot add device at 0000:01:03
> [   43.363277] shpchp 0000:00:00.0: Latch open on Slot(3)
> [   43.363320] shpchp 0000:00:00.0: Button pressed on Slot(3)
> [   43.363360] shpchp 0000:00:00.0: Card not present on Slot(3)
> [   43.363506] shpchp 0000:00:00.0: PCI slot #3 - powering on due to
> button press
> [   48.371835] shpchp 0000:00:00.0: No adapter on slot(3)
>
> Laurent
>