Re: [Xen-devel] Xen-unstable PVHdom0: Assertion 'IS_ALIGNED(dfn_x(dfn), (1ul << page_order))' failed at iommu.c:324

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

On Wed, Jan 23, 2019 at 12:39:21AM +0100, Sander Eikelenboom wrote:
> On 22/01/2019 17:14, Roger Pau Monné wrote:
> > On Sun, Jan 20, 2019 at 11:09:25PM +0100, Sander Eikelenboom wrote:
> >> On 18/01/2019 18:56, Roger Pau Monné wrote:
> >>> On Fri, Jan 18, 2019 at 03:17:57PM +0100, Sander Eikelenboom wrote:
> >>>> On 18/01/2019 13:50, Roger Pau Monné wrote:
> >>>>> On Fri, Jan 18, 2019 at 01:03:04PM +0100, Sander Eikelenboom wrote:
> >>>>>> Hi Roger,
> >>>>>>
> >>>>>> I gave PVH dom0 a spin, see how far I would get.
> >>>>>
> >>>>> Thanks!
> >>>>>
> >>>>>> With current xen-unstable unfortunately not that far, i got the splat 
> >>>>>> below.
> >>>>>
> >>>>> Yes, this was already reported:
> >>>>>
> >>>>> https://lists.xenproject.org/archives/html/xen-devel/2019-01/msg01030.html
> >>>>>> If you need more info, would like me to test a patch (or some other 
> >>>>>> git tree/branch), 
> >>>>>> I will be happy to give it a spin !
> >>>>>
> >>>>> Paul is working on a fix, but in the meantime just removing the
> >>>>> assertions should be fine:
> >>>>>
> >>>>> ---8<---
> >>>>> diff --git a/xen/drivers/passthrough/iommu.c 
> >>>>> b/xen/drivers/passthrough/iommu.c
> >>>>> index bd1af35a13..98e6fc35e2 100644
> >>>>> --- a/xen/drivers/passthrough/iommu.c
> >>>>> +++ b/xen/drivers/passthrough/iommu.c
> >>>>> @@ -321,9 +321,6 @@ int iommu_map(struct domain *d, dfn_t dfn, mfn_t 
> >>>>> mfn,
> >>>>>      if ( !iommu_enabled || !hd->platform_ops )
> >>>>>          return 0;
> >>>>>  
> >>>>> -    ASSERT(IS_ALIGNED(dfn_x(dfn), (1ul << page_order)));
> >>>>> -    ASSERT(IS_ALIGNED(mfn_x(mfn), (1ul << page_order)));
> >>>>> -
> >>>>>      for ( i = 0; i < (1ul << page_order); i++ )
> >>>>>      {
> >>>>>          rc = hd->platform_ops->map_page(d, dfn_add(dfn, i), 
> >>>>> mfn_add(mfn, i),
> >>>>>
> >>>>
> >>>> I gave that a spin and i now get a seemingly endless stream of 
> >>>> IO_PAGE_FAULTs
> >>>
> >>> You shouldn't get those page faults since they are for addresses that
> >>> belong to a reserved region, and that should be mapped into the p2m.
> >>> I've just tested on my AMD box and I'm also seeing errors (albeit
> >>> different ones), so I guess something broke since I last fixed PVH
> >>> Dom0 to boot on AMD hardware.
> >>>
> >>> I've also tested commit:
> >>>
> >>> commit fad6ba64a8c98bebb9374f390cc255fac05237ab (HEAD)
> >>> Author: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> >>> Date:   Fri Nov 30 12:10:00 2018 +0100
> >>> amd/iommu: skip host bridge devices when updating IOMMU page tables
> >>>
> >>> And it works on my AMD box and I'm able to boot as a PVH Dom0. Can you
> >>> give this commit a spin?
> >>>
> >>> Thanks, Roger.
> >>>
> >>
> >> Hi Roger,
> >>
> >> Tested that commit, but that didn't help.
> > 
> > Thanks! Sorry for the delay, I got sidetracked with something else.
> 
> No problem, it's not too urgent and probably a busy time with the remaining 
> 4.12 stuff.
>  
> > Can you please post the serial log when using the above commit?
> 
> Sure, I attached a log of:
>  - fad6ba64a8c98bebb9374f390cc255fac05237ab  dom0 PVH unsuccesful boot
>  - fad6ba64a8c98bebb9374f390cc255fac05237ab  dom0 PV    succesful boot

Thanks. So you get the same IO page faults.

I don't seem to be able to reproduce this behaviour on my AMD box, but
that might be just luck. I've been finding some issues today related
to the IOMMU, could you give the following patch a spin and paste the
serial log that you get.

Thanks, Roger.
---8<---
diff --git a/xen/drivers/passthrough/x86/iommu.c 
b/xen/drivers/passthrough/x86/iommu.c
index e40d7a7d7b..4fd75d4105 100644
--- a/xen/drivers/passthrough/x86/iommu.c
+++ b/xen/drivers/passthrough/x86/iommu.c
@@ -241,10 +241,11 @@ void __hwdom_init arch_iommu_hwdom_init(struct domain *d)
 
         if ( !hwdom_iommu_map(d, pfn, max_pfn) )
             continue;
-
+#if 0
         if ( paging_mode_translate(d) )
             rc = set_identity_p2m_entry(d, pfn, p2m_access_rw, 0);
         else
+#endif
             rc = iommu_map(d, _dfn(pfn), _mfn(pfn), PAGE_ORDER_4K,
                            IOMMUF_readable | IOMMUF_writable, &flush_flags);
 


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