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

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Feb 22, 2018 at 02:20:12PM +0800, Chao Gao wrote:
> 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.

Oh, OK, I had no idea we where planning to remove the AMD vIOMMU
stuff.

Thanks, Roger.

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