Re: [Xen-devel] [PATCH v4 08/28] x86/vvtd: Add MMIO handler for VVTD

[Chao Gao <chao.gao@xxxxxxxxx>]

On Fri, Feb 09, 2018 at 05:51:29PM +0000, Roger Pau Monné wrote:
>On Sat, Feb 10, 2018 at 01:21:09AM +0800, Chao Gao wrote:
>> On Fri, Feb 09, 2018 at 04:39:15PM +0000, Roger Pau Monné wrote:
>> >On Fri, Nov 17, 2017 at 02:22:15PM +0800, Chao Gao wrote:
>> >> This patch adds VVTD MMIO handler to deal with MMIO access.
>> >> 
>> >> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
>> >> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
>> >> ---
>> >> v4:
>> >>  - only trap the register emulated in vvtd_in_range().
>> >>    i.e. replace PAGE_SIZE with the VVTD_MAX_OFFSET
>> >> ---
>> >>  xen/drivers/passthrough/vtd/vvtd.c | 55 
>> >> ++++++++++++++++++++++++++++++++++++++
>> >>  1 file changed, 55 insertions(+)
>> >> 
>> >> diff --git a/xen/drivers/passthrough/vtd/vvtd.c 
>> >> b/xen/drivers/passthrough/vtd/vvtd.c
>> >> index 9f76ccf..d78d878 100644
>> >> --- a/xen/drivers/passthrough/vtd/vvtd.c
>> >> +++ b/xen/drivers/passthrough/vtd/vvtd.c
>> >
>> >Now that I look at this, this is the wrong folder. This should be in
>> >xen/arch/x86/hvm with the rest of the emulated devices.
>> 
>> It is a problem we discussed in previous versions. AMD puts its vIOMMU
>> (iommu_guest.c) in xen/drivers/passthrough/amd/. We are following what
>> they did. I don't have special taste on this. If no one objects to your
>> suggestion, I will move it to xen/arch/x86/hvm/. Maybe create a new
>> intel directory since it's intel-specific and won't be used by AMD.
>
>Oh, it's been quite some time since I've reviewed that, so TBH I
>didn't remember that discussion.
>
>If the AMD viommu thing is already there I guess it doesn't hurt...
>Also, have you checked whether it can be converted to use the
>infrastructure that you add here?

Not yet. It seems that we have no method to use AMD vIOMMU now.
And I notice that Wei plans to remove AMD vIOMMU.

I can convert AMD vIOMMU implementation to use this infrastructure if we
finally decide to preserve AMD vIOMMU.

Thanks
Chao

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