Re: [Xen-devel] [BUG] After upgrade to Xen 4.12.0 iommu=no-igfx

[Jan Beulich <jbeulich@xxxxxxxx>]

On 07.08.2019 09:35, Roger Pau Monné  wrote:
> On Tue, Aug 06, 2019 at 02:48:51PM -0700, Roman Shaposhnik wrote:
> > On Tue, Aug 6, 2019 at 9:18 AM Roger Pau Monné <roger.pau@xxxxxxxxxx> wrote:
> > > On Fri, Aug 02, 2019 at 10:05:40AM +0200, Roger Pau Monné wrote:
> > > > On Thu, Aug 01, 2019 at 11:25:04AM -0700, Roman Shaposhnik wrote:
> > > > > This patch completely fixes the problem for me!
> > > > >
> > > > > Thanks Roger! I'd love to see this in Xen 4.13
> > > > Thanks for testing!
> > > >
> > > > It's still not clear to me why the previous approach didn't work, but
> > > > I think this patch is better because it removes the usage of
> > > > {set/clear}_identity_p2m_entry from PV domains. I will submit this
> > > > formally now.
> > > Sorry to bother again, but since we still don't understand why the
> > > previous fix didn't work for you, and I can't reproduce this with my
> > > hardware, could you give the attached patch a try?
> > No worries -- and thanks for helping to get it over the finish line --
> > this is much appreciated!
> >
> > I'm happy to say that this latest patch is also working just fine. So
> > I guess this is the one that's going to land in Xen 4.13?
> No, not really, sorry this was still a debug patch.
>
> So I think the behaviour you are seeing can only be explained if the
> IOMMU is already enabled by the firmware when booting into Xen, can
> this be the case?
Even then - why would the existing flush not suffice in this case?

Jan

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