Re: [PATCH v3 0/3] virtio DMA API core stuff

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Woodhouse <dwmw2@infradead.org>,
	Andy Lutomirski <luto@amacapital.net>,
	"Michael S. Tsirkin" <mst@redhat.com>
Cc: linux-s390 <linux-s390@vger.kernel.org>,
	KVM <kvm@vger.kernel.org>,
	Sebastian Ott <sebott@linux.vnet.ibm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linux Virtualization <virtualization@lists.linux-foundation.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Joerg Roedel <jroedel@suse.de>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v3 0/3] virtio DMA API core stuff
Date: Fri, 20 Nov 2015 13:56:39 +1100	[thread overview]
Message-ID: <1447988199.3016.2.camel@kernel.crashing.org> (raw)
In-Reply-To: <1447976286.145626.122.camel@infradead.org>

On Thu, 2015-11-19 at 23:38 +0000, David Woodhouse wrote:
> 
> I understand that POWER and other platforms don't currently have a
> clean way to indicate that certain device don't have translation. And I
> understand that we may end up with a *quirk* which ensures that the DMA
> API does the right thing (i.e. nothing) in certain cases.
> 
> But we should *NOT* be involving the virtio device drivers in that
> quirk, in any way. And putting a feature bit in the virtio device
> itself doesn't seem at all sane either.
> 
> Bear in mind that qemu-system-x86_64 currently has the *same* problem
> with assigned physical devices. It's claiming they're translated, and
> they're not.

It's not that clear but yeah ... as I mentioned, I can't find a
way to do that quirk that won't break when we want to actually use
the iommu... 

Ben.

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization