Re: [Xen-devel] [PATCH for-4.12 1/8] dom0/pvh: align allocation and mapping order to start address

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

On Mon, Feb 04, 2019 at 09:41:34AM -0700, Jan Beulich wrote:
> >>> On 30.01.19 at 11:36, <roger.pau@xxxxxxxxxx> wrote:
> > Due to the recent changes in the iommu mapping logic, the start
> > addresses provided need to be aligned to the order intended to be
> > mapped.
> 
> Irrespective of your reply to Wei's similar request (where you've
> provided links to mails showing crashes) I'd like you to explain
> this better. This is in particular because I don't really see what
> "recent changes in the iommu mapping logic" you talk about.

Commit 725bf00a87f ("iommu / p2m: add a page_order parameter to
iommu_map/unmap_page()...") added the following two asserts to
iommu_map:

ASSERT(IS_ALIGNED(dfn_x(dfn), (1ul << page_order)));
ASSERT(IS_ALIGNED(mfn_x(mfn), (1ul << page_order)));

Previously iommu_map would add unaligned entries without complaining,
but now in debug builds the assert will trigger.

Maybe adding a 'Fixes' tag would help identifying what this commit is
trying to address?

Thanks, Roger.

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