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 08:56:48PM +0100, Sander Eikelenboom wrote:
> On 23/01/2019 19:25, Roger Pau Monné wrote:
> > 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.
> 
> Hi Roger,
> 
> Sure, on top of what ?
> - fad6ba64a8c98bebb9374f390cc255fac05237ab ?
> - xen-unstable ?
> - xen-unstable + Paul's patch ?

Hello,

Sorry for not proving the right context, let's try on top of
xen-unstable + Paul's patch.

Thanks, Roger.

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