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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20151120102141-mutt-send-email-mst@redhat.com>
Date:	Fri, 20 Nov 2015 10:34:18 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	David Woodhouse <dwmw2@...radead.org>,
	Andy Lutomirski <luto@...capital.net>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Sebastian Ott <sebott@...ux.vnet.ibm.com>,
	linux-s390 <linux-s390@...r.kernel.org>,
	Cornelia Huck <cornelia.huck@...ibm.com>,
	Joerg Roedel <jroedel@...e.de>,
	Linux Virtualization <virtualization@...ts.linux-foundation.org>,
	Christoph Hellwig <hch@....de>, KVM <kvm@...r.kernel.org>
Subject: Re: [PATCH v3 0/3] virtio DMA API core stuff

On Fri, Nov 20, 2015 at 01:56:39PM +1100, Benjamin Herrenschmidt wrote:
> 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.

Yes, I am not at all sure we need a quirk for assigned devices.
Better teach QEMU to make iommu work for them.


-- 
MST
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/