passthrough

passthrough

[George John]

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Hi,

Is it possible to give each channels of uart to different guests via pass
through mechanism?

regards
Georgeeldhojohn

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Re: passthrough

[Jan Beulich]

>>> On 23.05.17 at 11:38, <georgeeldhojohn@gmail.com> wrote:
> Is it possible to give each channels of uart to different guests via pass
> through mechanism?

If each channel is represented by a separate PCI device/function,
then likely yes. If they're all one PCI device, or not a PCI device
at all, then you may be able to hand them through (by allowing
each guest to access the respective port numbers or MMIO space),
but an IOMMU in the system could not be leveraged to make this
half way secure.

Jan


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Re: passthrough

[George John]

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Thanks for the reply. we are using renesas rcar h3 board. Does it supports?

On Tuesday, May 23, 2017, Jan Beulich <JBeulich@suse.com> wrote:

> >>> On 23.05.17 at 11:38, <georgeeldhojohn@gmail.com <javascript:;>>
> wrote:
> > Is it possible to give each channels of uart to different guests via pass
> > through mechanism?
>
> If each channel is represented by a separate PCI device/function,
> then likely yes. If they're all one PCI device, or not a PCI device
> at all, then you may be able to hand them through (by allowing
> each guest to access the respective port numbers or MMIO space),
> but an IOMMU in the system could not be leveraged to make this
> half way secure.
>
> Jan
>
>

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Re: passthrough

[Jan Beulich]

>>> On 23.05.17 at 14:53, <georgeeldhojohn@gmail.com> wrote:
> Thanks for the reply. we are using renesas rcar h3 board. Does it supports?

I have no idea, I'm an x86 person.

Also please don't top-post.

Jan

> On Tuesday, May 23, 2017, Jan Beulich <JBeulich@suse.com> wrote:
> 
>> >>> On 23.05.17 at 11:38, <georgeeldhojohn@gmail.com <javascript:;>>
>> wrote:
>> > Is it possible to give each channels of uart to different guests via pass
>> > through mechanism?
>>
>> If each channel is represented by a separate PCI device/function,
>> then likely yes. If they're all one PCI device, or not a PCI device
>> at all, then you may be able to hand them through (by allowing
>> each guest to access the respective port numbers or MMIO space),
>> but an IOMMU in the system could not be leveraged to make this
>> half way secure.
>>
>> Jan
>>
>>




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Re: passthrough

[Julien Grall]

Hello,

On 23/05/17 14:18, Jan Beulich wrote:
>>>> On 23.05.17 at 14:53, <georgeeldhojohn@gmail.com> wrote:
>> Thanks for the reply. we are using renesas rcar h3 board. Does it supports?

A general rule is to provide as much as details on your mail so we can 
provide the best feedback.

In this case, I don't fully understand what you want to passthrough. Are 
those UARTs part of PCI device or integrated device?

The work for PCI passthrough is still on-going. For integrated device, 
you may want to look at [1].

Cheers,

[1] https://events.linuxfoundation.org/sites/events/files/slides/talk_5.pdf

-- 
Julien Grall

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Re: passthrough

[Andrii Anisov]

Dear John,


I would speak about XEN on ARM further.

Basically you need a passthrough in XEN terms in case you want a bus 
initiator (i.e. DMA capable) device to be assigned to DomU.

For a passive device it's pretty enough to assign MMIO ranges and 
interrupts using guest domain config. The pitfall here is that a device 
tree generated for guest domain by xen tools will not have any assigned 
device specific nodes.

But a setup with earlyprintk from one guest into the second console of a 
Salvator-X board is pretty straightforward. Something more complex will 
require additional hacks.


On 23.05.17 15:53, George John wrote:
> Thanks for the reply. we are using renesas rcar h3 board. Does it 
> supports?
XEN passthrough functionality relies on IOMMU. The R-Car Gen3 SoCs have 
a custom IOMMU named IPMMU. XEN does not support IPMMU yet.

-- 

*Andrii Anisov*



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