From: Paolo Bonzini <pbonzini@redhat.com>
To: Benjamin Herrenschmidt <benh@au1.ibm.com>,
Andy Lutomirski <luto@amacapital.net>
Cc: "linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Linux Virtualization <virtualization@lists.linux-foundation.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
"linux390@de.ibm.com" <linux390@de.ibm.com>
Subject: Re: [PATCH v4 0/4] virtio: Clean up scatterlists and use the DMA API
Date: Wed, 03 Sep 2014 09:43:59 +0200 [thread overview]
Message-ID: <5406C6BF.8040908@redhat.com> (raw)
In-Reply-To: <1409700010.30640.67.camel@pasglop>
Il 03/09/2014 01:20, Benjamin Herrenschmidt ha scritto:
> I wouldn't be so certain, as I said, the way virtio is implemented in
> qemu bypass the DMA layer which is where IOMMUs sit. The fact that
> currently x86 doesn't put an IOMMU there is not even garanteed, is it ?
> What happens if you try to mix and match virtio and other emulated
> devices that require the iommu on the same bus ?
As far as QEMU is concerned, it's trivial to add a property like
"direct-ram-access" that selects whether to bypass the IOMMU or not.
And it would have zero performance cost if direct RAM access is enabled,
compared to the current code.
If possible, I would quirk it in the PPC code.
Paolo
next prev parent reply other threads:[~2014-09-03 7:43 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-01 17:39 [PATCH v4 0/4] virtio: Clean up scatterlists and use the DMA API Andy Lutomirski
2014-09-01 17:39 ` [PATCH v4 1/4] virtio_ring: Support DMA APIs if requested Andy Lutomirski
2014-09-01 17:39 ` [PATCH v4 2/4] virtio_pci: Use the DMA API for virtqueues Andy Lutomirski
2014-09-01 17:39 ` [PATCH v4 3/4] virtio_net: Don't set the end flag on reusable sg entries Andy Lutomirski
2014-09-01 17:39 ` [PATCH v4 4/4] virtio_net: Stop doing DMA from the stack Andy Lutomirski
2014-09-01 22:16 ` [PATCH v4 0/4] virtio: Clean up scatterlists and use the DMA API Benjamin Herrenschmidt
2014-09-02 5:55 ` Andy Lutomirski
2014-09-02 20:53 ` Benjamin Herrenschmidt
2014-09-02 20:56 ` Konrad Rzeszutek Wilk
2014-09-02 21:08 ` Benjamin Herrenschmidt
2014-09-02 21:37 ` Andy Lutomirski
2014-09-02 22:10 ` Benjamin Herrenschmidt
2014-09-02 23:11 ` Andy Lutomirski
2014-09-02 23:20 ` Benjamin Herrenschmidt
2014-09-02 23:42 ` Andy Lutomirski
2014-09-03 0:25 ` Benjamin Herrenschmidt
2014-09-03 0:32 ` Andy Lutomirski
2014-09-03 0:43 ` Benjamin Herrenschmidt
2014-09-04 2:03 ` Andy Lutomirski
2014-09-03 7:47 ` Paolo Bonzini
2014-09-03 7:52 ` Andy Lutomirski
2014-09-03 8:01 ` Paolo Bonzini
2014-09-03 8:05 ` Benjamin Herrenschmidt
2014-09-03 12:11 ` Paolo Bonzini
2014-09-03 15:07 ` Andy Lutomirski
2014-09-03 15:11 ` Paolo Bonzini
2014-09-03 16:39 ` Michael S. Tsirkin
2014-09-03 20:38 ` Andy Lutomirski
2014-09-03 7:43 ` Paolo Bonzini [this message]
2014-09-03 6:42 ` Rusty Russell
2014-09-03 7:50 ` Andy Lutomirski
2014-09-05 2:31 ` Rusty Russell
2014-09-05 2:57 ` Andy Lutomirski
2014-09-05 5:20 ` Benjamin Herrenschmidt
2014-09-05 7:33 ` Christian Borntraeger
2014-09-10 15:36 ` Christopher Covington
2014-09-10 16:15 ` Andy Lutomirski
2014-09-05 5:16 ` Benjamin Herrenschmidt
2014-09-14 8:58 ` Michael S. Tsirkin
2014-09-03 12:51 ` Michael S. Tsirkin
2014-09-05 2:32 ` Rusty Russell
2014-09-05 3:06 ` Andy Lutomirski
2014-09-02 21:10 ` Michael S. Tsirkin
2014-09-02 21:49 ` Andy Lutomirski
-- strict thread matches above, loose matches on Subject: below --
2015-07-28 1:08 Andy Lutomirski
2015-07-28 7:05 ` Christian Borntraeger
2015-07-28 7:05 ` Christian Borntraeger
2015-07-28 8:16 ` Paolo Bonzini
2015-07-28 10:12 ` Benjamin Herrenschmidt
2015-07-28 12:46 ` Paolo Bonzini
2015-07-28 12:46 ` Paolo Bonzini
2015-07-28 13:06 ` Michael S. Tsirkin
2015-07-28 13:06 ` Michael S. Tsirkin
2015-07-28 13:11 ` Jan Kiszka
2015-07-28 16:11 ` Andy Lutomirski
2015-07-28 16:44 ` Jan Kiszka
2015-07-28 16:44 ` Jan Kiszka
2015-07-28 17:10 ` Andy Lutomirski
2015-07-28 17:10 ` Andy Lutomirski
2015-07-28 17:17 ` Jan Kiszka
2015-07-28 18:22 ` Andy Lutomirski
2015-07-28 19:06 ` Jan Kiszka
2015-07-28 19:24 ` Andy Lutomirski
2015-07-28 19:24 ` Andy Lutomirski
2015-07-28 19:33 ` Jan Kiszka
2015-07-28 19:33 ` Jan Kiszka
2015-07-28 21:16 ` Andy Lutomirski
2015-07-28 21:16 ` Andy Lutomirski
2015-07-28 22:43 ` Andy Lutomirski
2015-07-28 22:43 ` Andy Lutomirski
2015-07-28 23:21 ` Benjamin Herrenschmidt
2015-07-28 23:33 ` Andy Lutomirski
2015-07-28 23:33 ` Andy Lutomirski
2015-07-29 0:36 ` Benjamin Herrenschmidt
2015-07-29 0:36 ` Benjamin Herrenschmidt
2015-07-29 0:47 ` Andy Lutomirski
2015-07-29 0:54 ` Benjamin Herrenschmidt
2015-07-29 0:54 ` Benjamin Herrenschmidt
2015-07-29 8:17 ` Paolo Bonzini
2015-07-29 8:17 ` Paolo Bonzini
2015-07-29 8:20 ` Jan Kiszka
2015-07-29 8:20 ` Jan Kiszka
2015-07-29 9:21 ` Benjamin Herrenschmidt
2015-07-29 9:21 ` Benjamin Herrenschmidt
2015-07-29 0:47 ` Andy Lutomirski
2015-07-29 8:07 ` Jan Kiszka
2015-07-29 8:07 ` Jan Kiszka
2015-07-28 23:21 ` Benjamin Herrenschmidt
2015-07-28 19:06 ` Jan Kiszka
2015-07-28 18:22 ` Andy Lutomirski
2015-07-28 17:17 ` Jan Kiszka
2015-07-28 16:11 ` Andy Lutomirski
2015-07-28 16:36 ` Paolo Bonzini
2015-07-28 16:42 ` Jan Kiszka
2015-07-28 17:15 ` Paolo Bonzini
2015-07-28 17:15 ` Paolo Bonzini
2015-07-28 17:19 ` Jan Kiszka
2015-07-28 17:19 ` Jan Kiszka
2015-07-28 17:31 ` Paolo Bonzini
2015-07-28 17:31 ` Paolo Bonzini
2015-07-28 16:42 ` Jan Kiszka
2015-07-28 16:36 ` Paolo Bonzini
2015-07-28 13:11 ` Jan Kiszka
2015-07-28 10:12 ` Benjamin Herrenschmidt
2015-07-28 8:16 ` Paolo Bonzini
2015-07-28 13:08 ` Michael S. Tsirkin
2015-07-28 13:08 ` Michael S. Tsirkin
2015-07-28 1:08 Andy Lutomirski
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