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Date:   Wed, 16 Sep 2020 11:41:59 +0200
From:   Cornelia Huck <cohuck@redhat.com>
To:     Matthew Rosato <mjrosato@linux.ibm.com>
Cc:     alex.williamson@redhat.com, pmorel@linux.ibm.com,
        schnelle@linux.ibm.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] vfio iommu: Add dma available capability
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        <1600196718-23238-2-git-send-email-mjrosato@linux.ibm.com>
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On Tue, 15 Sep 2020 15:05:18 -0400
Matthew Rosato <mjrosato@linux.ibm.com> wrote:

> Commit 492855939bdb ("vfio/type1: Limit DMA mappings per container")
> added the ability to limit the number of memory backed DMA mappings.
> However on s390x, when lazy mapping is in use, we use a very large
> number of concurrent mappings.  Let's provide the current allowable
> number of DMA mappings to userspace via the IOMMU info chain so that
> userspace can take appropriate mitigation.
> 
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 17 +++++++++++++++++
>  include/uapi/linux/vfio.h       | 15 +++++++++++++++
>  2 files changed, 32 insertions(+)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>