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

[Fabio Fantoni]

Il 08/05/2014 13:23, Gonglei (Arei) ha scritto:
> Hi,
>
> > -----Original Message-----
> > From: Fabio Fantoni [mailto:address@hidden
> > Sent: Thursday, May 08, 2014 4:17 PM
> > To: Gonglei (Arei); address@hidden; address@hidden
> > Cc: address@hidden; address@hidden;
> > address@hidden; address@hidden; 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 <address@hidden>
> > > > > > Signed-off-by: Gonglei <address@hidden>
> > > > Tested-by: Fabio Fantoni <address@hidden>
> > > >
> > > > 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

optional-devices.jpg
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