[Engine-devel] [libvirt]Supporting native USB in oVirt
Hans de Goede
hdegoede at redhat.com
Thu May 10 12:12:42 UTC 2012
Hi,
On 05/10/2012 01:39 PM, Oved Ourfalli wrote:
> Rephrasing my question a bit, to make it more clear.
> We are now working on adding the support for native USB devices on oVirt.
>
> This requires adding composite PCI devices to a VM (details below), requiring specific set of restrictions on the addresses of these devices, and the connections between them.
> Is it possible to add such a composite set of devices to a VM while using automatic address assignment, as we do today on the other PCI devices?
To be clear, what the ovirt-engine people want to do (AFAIK), is add an EHCI controller
with UHCI companion controllers to a vm, which would normally be done in the xml file
like this:
<controller type='usb' index='0' model='ich9-ehci1'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x7'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci1'>
<master startport='0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0' multifunction='on'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci2'>
<master startport='2'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x1'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci3'>
<master startport='4'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x2'/>
</controller>
Without manually specifying the addresses, ie they want to be able to write
something like:
<controller type='usb' index='0' model='ich9-ehci1'>
</controller>
<controller type='usb' index='0' model='ich9-uhci1'>
<master startport='0'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci2'>
<master startport='2'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci3'>
<master startport='4'/>
</controller>
Which currently does not work, and even if it would work
libvirt does not seem to know that all devices here should
share one pci slot using different functions of that slot
(and the EHCI controller must have the highest function)
I can imagine a syntax like this:
<controller type='usb' index='0' model='ich9-ehci1'>
</controller>
<controller type='usb' index='0' model='ich9-uhci1'>
<master id='usb' startport='0'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci2'>
<master id='usb' startport='2'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci3'>
<master id='usb' startport='4'/>
</controller>
Where the id='usb' tells libvirt which master usb controller
the companions belong to, and that libvirt would then
automatically assign them all the same pci-slot, with different
function number, ensuring the EHCI device gets the highest
function nr.
Regards,
Hans
>
> More details below...
>
> Thank you,
> Oved
>
> ----- Original Message -----
>> From: "Hans de Goede"<hdegoede at redhat.com>
>> To: "Oved Ourfalli"<ovedo at redhat.com>
>> Cc: "engine-devel"<engine-devel at ovirt.org>, libvirt-list at redhat.com
>> Sent: Thursday, May 10, 2012 11:32:15 AM
>> Subject: Re: [Engine-devel] [libvirt]Supporting native USB in oVirt
>>
>> Hi Oved,
>>
>> I think it will help if you can re-formulate things into
>> a question for the libvirt developers. e.g. something along
>> the lines of: "is it possible to add composite PCI devices
>> to a vm while using automatic address assignment" ?
>>
>> Regards,
>>
>> Hans
>>
>>
>> On 05/09/2012 03:46 PM, Oved Ourfalli wrote:
>>> Hey,
>>>
>>> We are now working on adding the support for native USB devices on
>>> oVirt, and we have some difficulties.
>>> Please see the details/discussion below.
>>>
>>> Thank you for your help,
>>> Oved
>>>
>>> ----- Forwarded Message -----
>>> From: "Itamar Heim"<iheim at redhat.com>
>>> To: "Michal Privoznik"<mprivozn at redhat.com>
>>> Cc: "Oved Ourfalli"<ovedo at redhat.com>, "Dave
>>> Allan"<dallan at redhat.com>, "Jiri Denemark"<jdenemar at redhat.com>,
>>> "Igor Lvovsky"<ilvovsky at redhat.com>, "Eli
>>> Mesika"<emesika at redhat.com>, "Hans de Goede"<hdegoede at redhat.com>,
>>> "Dan Kenigsberg"<danken at redhat.com>, "Andrew
>>> Cathrow"<acathrow at redhat.com>
>>> Sent: Wednesday, May 9, 2012 1:18:40 PM
>>> Subject: Re: Supporting native USB in oVirt
>>>
>>> On 05/09/2012 01:12 PM, Michal Privoznik wrote:
>>>> On 08.05.2012 09:19, Oved Ourfalli wrote:
>>>>> Hi,
>>>>>
>>>>> We are now working on adding the support for native USB devices
>>>>> on oVirt.
>>>>> As far as we understand, in order to use it we need to pass the
>>>>> following devices with the following restrictions (according to
>>>>> the EHCI spec):
>>>>> 1. EHCI USB controller - with the highest function number, #7.
>>>>>
>>>>> devices='{type:controller,device:usb,model:ich9-ehci1,address:{type:pci,domain:0x0000,bus:0x00,slot:0x04,function:0x7}}'
>>>>>
>>>>> 2. 3 UHCI USB controllers, on the same bus and PCI slot as the
>>>>> EHCI controller. Set the multifunction bit to on, on the
>>>>> controller with function #0.
>>>>>
>>>>> devices='{type:controller,device:usb,model:ich9-uhci1,master:{startport:0},address:{type:pci,domain:0x0000,bus:0x00,slot:0x04,function:0x0,multifunction:on}}'
>>>>> devices='{type:controller,device:usb,model:ich9-uhci2,master:{startport:2},address:{type:pci,domain:0x0000,bus:0x00,slot:0x04,function:0x1}}'
>>>>> devices='{type:controller,device:usb,model:ich9-uhci3,master:{startport:4},address:{type:pci,domain:0x0000,bus:0x00,slot:0x04,function:0x2}}'
>>>>>
>>>>> 3. USB redirect devices (according to the needed number of USB
>>>>> slots, maximum 6) on the same bus, each one having a different
>>>>> port.
>>>>>
>>>>> devices='{type:redir,device:spicevmc,bus:usb,address:{type:usb,bus:0,port:1}}'
>>>>> devices='{type:redir,device:spicevmc,bus:usb,address:{type:usb,bus:0,port:2}}'
>>>>> devices='{type:redir,device:spicevmc,bus:usb,address:{type:usb,bus:0,port:3}}'
>>>>> devices='{type:redir,device:spicevmc,bus:usb,address:{type:usb,bus:0,port:4}}'
>>>>> devices='{type:redir,device:spicevmc,bus:usb,address:{type:usb,bus:0,port:5}}'
>>>>> devices='{type:redir,device:spicevmc,bus:usb,address:{type:usb,bus:0,port:6}}'
>>>>>
>>>>> 4. If we want more than 6 USB slots, we need to have 2 EHCI
>>>>> controllers, and 6 UHCI controllers, that are consistent with
>>>>> the restrictions above, on different bus.
>>>>> (we need them to be on different bus, since the connection
>>>>> between the redirect devices and the controllers is the bus).
>>>>>
>>>>> According to Hans (cc-ed), if we let libvirt pick its own
>>>>> addresses, it will put each controller of the composite USB
>>>>> controller device on its own pci slot, which is a violation of
>>>>> the EHCI spec.
>>>>
>>>>>
>>>>> The problem is that the oVirt engine is not aware of addresses.
>>>>> They aren't managed by it.
>>>>> They are chosen automatically by libvirt, returned to the engine,
>>>>> and they saved in the engine database in order to provide the
>>>>> ability to retain the same PCI addresses after VM restart.
>>>>>
>>>>> So, in order to support the EHCI spec, oVirt will have to be
>>>>> aware of addresses, manage them (allocate them, check for
>>>>> collisions, update on every libvirt change regarding that,
>>>>> etc...). Obviously, it doesn't feel right, and in fact it is
>>>>> also not feasible, to manage these addresses in the oVirt
>>>>> domain.
>>>>>
>>>>> Is all the above correct, or are we missing something?
>>>>> If so, can you address the issues above, and provide the ability
>>>>> to manage these devices in libvirt?
>>>>
>>>> Let's have this conversation upstream (libvirt-list at redhat.com).
>>>> Many
>>>> developers are there so if there's anything libvirt can do, we
>>>> should
>>>> agree on concept there.
>>>
>>> --
>>> libvir-list mailing list
>>> libvir-list at redhat.com
>>> https://www.redhat.com/mailman/listinfo/libvir-list
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