linux-kernel - Re: [PATCH v4 4/7] vfio: ap: register IOMMU VFIO notifier

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Message-Id: <20190228175513.06504ae6@oc2783563651>
Date:   Thu, 28 Feb 2019 17:55:13 +0100
From:   Halil Pasic <pasic@...ux.ibm.com>
To:     Pierre Morel <pmorel@...ux.ibm.com>
Cc:     Christian Borntraeger <borntraeger@...ibm.com>,
        alex.williamson@...hat.com, cohuck@...hat.com,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org, frankja@...ux.ibm.com, akrowiak@...ux.ibm.com,
        david@...hat.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, freude@...ux.ibm.com, mimu@...ux.ibm.com
Subject: Re: [PATCH v4 4/7] vfio: ap: register IOMMU VFIO notifier

On Thu, 28 Feb 2019 09:48:39 +0100
Pierre Morel <pmorel@...ux.ibm.com> wrote:

> On 28/02/2019 09:23, Christian Borntraeger wrote:
> > On 22.02.2019 16:29, Pierre Morel wrote:
> >> To be able to use the VFIO interface to facilitate the
> >> mediated device memory pining/unpining we need to register
> >> a notifier for IOMMU.
> > 
> > You might want to add that while we start to pin one guest page for the
> > interrupt indicator byte in the next patch, this is still ok with ballooning
> > as this page will never be used by the guest virtio-balloon driver. So the
> > pinned page will never be freed. And even a broken guest does so, that would
> > not impact the host as the original page is still in control by vfio.
> > 
> 
> Thanks, I ll do.
> 

I recall a comment in qemu that says vfio-ap does not pin any pages.
That one needs to be fixed up as well.

Regards,
Halil

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