Re: [Xen-devel] [PATCH 0/3] AMD/IOMMU: re-work mode updating

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

On 06/11/2019 16:16, Jan Beulich wrote:
> update_paging_mode() in the AMD IOMMU code expects to be invoked with
> the PCI devices lock held. The check occurring only when the mode
> actually needs updating, the violation of this rule by the majority
> of callers did go unnoticed until per-domain IOMMU setup was changed
> to do away with on-demand creation of IOMMU page tables.
> 
> Unfortunately the only half way reasonable fix to this that I could
> come up with requires more re-work than would seem desirable at this
> time of the release process, but addressing the issue seems
> unavoidable to me as its manifestation is a regression from the
> IOMMU page table setup re-work. The change also isn't without risk
> of further regressions - if in patch 2 I've missed a code path that
> would also need to invoke the new hook, then this might mean non-
> working guests (with passed-through devices on AMD hardware).
> 
> 1: AMD/IOMMU: don't needlessly trigger errors/crashes when unmapping a page
> 2: introduce GFN notification for translated domains
> 3: AMD/IOMMU: use notify_dfn() hook to update paging mode
> 
> Jan
> 

Hi Jan,

I just tested and I don't get the  "pcidevs" message any more.

I assume this only was a fix for that issue, so it's probably expected
that the other issue:
   AMD-Vi: INVALID_DEV_REQUEST 00000800 8a000000 f8000840 000000fd
   and malfunctioning device in one of the guests.
is still around.

--
Sander

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