Date: Sun, 8 Nov 2015 12:49:46 +0100
From: Joerg Roedel <jroedel@suse.de>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Andy Lutomirski <luto@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Cornelia Huck <cornelia.huck@de.ibm.com>,
        Sebastian Ott <sebott@linux.vnet.ibm.com>,
        Paolo Bonzini <pbonzini@redhat.com>, Christoph Hellwig <hch@lst.de>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        KVM <kvm@vger.kernel.org>, Martin Schwidefsky <schwidefsky@de.ibm.com>,
        linux-s390 <linux-s390@vger.kernel.org>,
        Linux Virtualization <virtualization@lists.linux-foundation.org>
Subject: Re: [PATCH v3 0/3] virtio DMA API core stuff
Message-ID: <20151108114946.GG2255@suse.de>
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On Sun, Nov 08, 2015 at 12:37:47PM +0200, Michael S. Tsirkin wrote:
> I have no problem with that. For example, can we teach
> the DMA API on intel x86 to use PT for virtio by default?
> That would allow merging Andy's patches with
> full compatibility with old guests and hosts.

Well, the only incompatibility comes from an experimental qemu feature,
more explicitly from a bug in that features implementation. So why
should we work around that in the kernel? I think it is not too hard to
fix qemu to generate a correct DMAR table which excludes the virtio
devices from iommu translation.


	Joerg

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