linux-kernel - Re: [PATCH] iommu: intel: remove flooding of non-error logs, when new-DMA-PTE is the same as old-DMA-PTE.

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Message-ID: <20211004163146.6b34936b.alex.williamson@redhat.com>
Date:   Mon, 4 Oct 2021 16:31:46 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Ajay Garg <ajaygargnsit@...il.com>
Cc:     Lu Baolu <baolu.lu@...ux.intel.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: Re: [PATCH] iommu: intel: remove flooding of non-error logs, when
 new-DMA-PTE is the same as old-DMA-PTE.

On Sat, 2 Oct 2021 22:48:24 +0530
Ajay Garg <ajaygargnsit@...il.com> wrote:

> Thanks Lu for the reply.
> 
> >
> > Isn't the domain should be switched from a default domain to an
> > unmanaged domain when the device is assigned to the guest?
> >
> > Even you want to r-setup the same mappings, you need to un-map all
> > existing mappings, right?
> >  
> 
> Hmm, I guess that's a (design) decision the KVM/QEMU/VFIO communities
> need to take.
> May be the patch could suppress the flooding till then?

No, this is wrong.  The pte values should not exist, it doesn't matter
that they're the same.  Is the host driver failing to remove mappings
and somehow they persist in the new vfio owned domain?  There's
definitely a bug beyond logging going on here.  Thanks,

Alex