Re: [Xen-devel] [PATCH V3 11/29] x86/hvm: Introduce a emulated VTD for HVM

[Lan Tianyu <tianyu.lan@xxxxxxxxx>]

On 2017年10月20日 14:56, Jan Beulich wrote:
>>>> On 20.10.17 at 04:46, <chao.gao@xxxxxxxxx> wrote:
>> On Thu, Oct 19, 2017 at 12:20:35PM +0100, Roger Pau Monné wrote:
>>> On Thu, Sep 21, 2017 at 11:01:52PM -0400, Lan Tianyu wrote:
>>>> From: Chao Gao <chao.gao@xxxxxxxxx>
>>>>
>>>> This patch adds create/destroy function for the emulated VTD
>>>> and adapts it to the common VIOMMU abstraction.
>>>>
>>>> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
>>>> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
>>>> ---
>>>>  
>>>> -obj-y += iommu.o
>>>>  obj-y += dmar.o
>>>> -obj-y += utils.o
>>>> -obj-y += qinval.o
>>>>  obj-y += intremap.o
>>>> +obj-y += iommu.o
>>>> +obj-y += qinval.o
>>>>  obj-y += quirks.o
>>>> +obj-y += utils.o
>>>
>>> Why do you need to shuffle the list above?
>>
>> I placed them in alphabetic order.
> 
> Which is appreciated. But this being non-essential for the patch, it
> would avoid (valid) reviewer questions if you said in the description
> this is an intended but non-essential change.
> 
>>> Also I'm not sure the Intel vIOMMU implementation should live here. As
>>> you can see the path is:
>>>
>>> xen/drivers/passthrough/vtd/
>>>
>>> The vIOMMU is not tied to passthrough at all, so I would rather place
>>> it in:
> 
> Hmm, is vIOMMU usable without an actual backing IOMMU?

For interrupt remapping support, we can emulate it without physical IOMMU.

> 
>>> xen/drivers/vvtd/
>>>
>>> Or maybe you can create something like:
>>>
>>> xen/drivers/viommu/
>>>
>>> So that all vIOMMU implementations can share some code.
>>>
>>
>> vvtd and vtd use the same header files (i.g. vtd.h). That is why we put
>> it there.  If that, we shoule move the related header files to a public
>> directory.
> 
> And AMD (long ago) had placed their (still incomplete) virtual
> implementation into the same directory as well. I.e. at this point
> I'm not really opposed to the proposed placement here, albeit
> I can see the point of Roger's argument.
> 
> Jan
> 


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