linux-kernel - Re: [PATCH v2 1/3] iommu/s390: Fix duplicate domain attachments

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Message-ID: <YzMrSIGMPSgJ94sG@nvidia.com>
Date:   Tue, 27 Sep 2022 13:56:40 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Niklas Schnelle <schnelle@...ux.ibm.com>
Cc:     Matthew Rosato <mjrosato@...ux.ibm.com>,
        Pierre Morel <pmorel@...ux.ibm.com>, iommu@...ts.linux.dev,
        linux-s390@...r.kernel.org, borntraeger@...ux.ibm.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com,
        gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
        svens@...ux.ibm.com, joro@...tes.org, will@...nel.org,
        robin.murphy@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] iommu/s390: Fix duplicate domain attachments

On Tue, Sep 27, 2022 at 06:33:48PM +0200, Niklas Schnelle wrote:
 
> Not sure what the non-MSI reservation is for? It does seem like x86_64
> also uses this for quite large ranges.

There are lots of things that are unsuitable for DMA on x86 platforms,
unfortunately.. But yeah, I'm not sure either.

> This is because I'm getting a map request for an IOVA in the reserved
> region.

How come? iova_reserve_iommu_regions() reads the reserved regions and
loads them as reserved into the iovad which should cause
iommu_dma_alloc_iova() and alloc_iova_fast() to not return values in
those ranges.

It all looks like it is supposed to work

Did something go wrong in the initialization order perhaps?

Jason