Re: [Qemu-devel] [PATCH v3] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching

[Fabio Fantoni <fabio.fantoni@m2r.biz>]

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Il 08/05/2014 13:23, Gonglei (Arei) ha scritto:
> Hi,
>
>> -----Original Message-----
>> From: Fabio Fantoni [mailto:fabio.fantoni@m2r.biz]
>> Sent: Thursday, May 08, 2014 4:17 PM
>> To: Gonglei (Arei); qemu-devel@nongnu.org; xen-devel@lists.xen.org
>> Cc: Ian.Campbell@citrix.com; JBeulich@suse.com;
>> stefano.stabellini@eu.citrix.com; anthony.perard@citrix.com; Huangweidong
>> (C); Hanweidong (Randy); Gaowei (UVP); Michael S. Tsirkin
>> Subject: Re: [PATCH v3] Hvmloader: Modify ACPI to only supply _EJ0 methods
>> for PCIslots that support hotplug by runtime patching
>>
>> Il 08/05/2014 06:12, Gonglei (Arei) ha scritto:
>>> Hi,
>>>
>>>>>> In Xen platform, after using upstream qemu, the all of pci devices will
>> show
>>>>>> hotplug in the windows guest. In this situation, the windows guest may
>>>> occur
>>>>>> blue screen when VM' user click the icon of VGA card for trying unplug
>> VGA
>>>>>> card.
>>>>>> However, we don't hope VM's user can do such dangerous operation, and
>>>>>> showing
>>>>>> all pci devices inside the guest OS is unfriendly.
>>>>>>
>>>>>> This is done by runtime patching:
>>>>>>      - Rename _EJ0 methods for PCI slots in DSDT to EJ0_:note that this
>> has
>>>> the
>>>>>>        same checksum, but is ignored by OSPM.
>>>>>>      - At compile time, look for these methods in ASL source,find the
>>>> matching
>>>>>> AML,
>>>>>>        and store the offsets of these methods in a table named
>>>> aml_ej0_data.
>>>>>>      - At run time, go over aml_ej0_data, check which slots not support
>>>> hotplug
>>>>>> and
>>>>>>        patch the ACPI table, replacing _EJ0 with EJ0_.
>>>>>>
>>>>>> Signed-off-by: Gaowei <gao.gaowei@huawei.com>
>>>>>> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
>>>> Tested-by: Fabio Fantoni <fabio.fantoni@m2r.biz>
>>>>
>>>> Thanks for this very useful patch that avoid that unaware users or as
>>>> mistake make windows domUs unusable.
>>>>
>>> Thanks.
>>>
>>>> I tried to quickly look at the patch to understand how to add some
>>>> optional components, for example on my case the pv drivers, the audio
>>>> card and the spice guest tools (see attachment) but I don't understand
>>>> how to do it.
>>>> Can someone give me some advices about it please?
>>>>
>>> Maybe you can hard code at libxl__build_device_model_args_new()
>>> in tools/libxl/libxl_dm.c
>>>
>>>
>>> Best regards,
>>> -Gonglei
>>>
>> I believe I not understand what you mean.
>> About adding these components I already do this:
>> - gplpv: http://wiki.xen.org/wiki/Xen_Windows_GplPv
>> http://www.ejbdigital.com.au/gplpv
>> - spice:
>> http://xenbits.xen.org/docs/unstable/man/xl.cfg.5.html#spice_graphics_suppo
>> rt
>> http://www.spice-space.org/download/binaries/spice-guest-tools/
>> - audio: add soundhw="hda" in domU's xl cfg file
>>
>> This patch disables hotplug capabilities from essential pci devices.
>>
> No, if pci devices do not support hotplug, which class's no_hotplug property will be
> set to 1, then the pci device will not show in guest os, opposite will be shown, such
> as your pv drivers and Intel hda card.
>
> Please see intel_hda_class_init_common() and xen_platform_class_init() functions.
> As a comparison, you can see vga devices' class init function cirrus_vga_class_init()
> has below code:
>
> k->no_hotplug = 1;
>
> If I understand what you mean wrong, please forgive me.

I saw in qemu code that intel_hda_class_init_common() and 
xen_platform_class_init() functions (and probably also virtio serial 
one) not have k->no_hotplug but in windows domUs show them in hotplug 
devices list, also with this your patch applied. (see part of 
screenshoot in attachment)
I not understand how to remove also them from windows hotplug devices list.

Thanks for any reply and sorry for my bad english.

>
>> What I mean if there is a way to prevent some other components being
>> part of the above list of hotplug devices.
>>
>> Thanks for any reply and sorry for my bad english.
> Best regards,
> -Gonglei


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