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Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api |
Date: |
Wed, 27 Apr 2016 17:38:51 +0300 |
On Wed, Apr 27, 2016 at 07:31:43AM -0700, Andy Lutomirski wrote:
> On Wed, Apr 27, 2016 at 7:23 AM, Joerg Roedel <address@hidden> wrote:
> > On Wed, Apr 27, 2016 at 04:37:04PM +0300, Michael S. Tsirkin wrote:
> >> One correction: it's a feature of the device in the system.
> >> There could be a mix of devices bypassing and not
> >> bypassing the IOMMU.
> >
> > No, it really is not. A device can't chose to bypass the IOMMU. But the
> > IOMMU can chose to let the device bypass. So any fix here belongs
> > into the platform/iommu code too and not into some driver.
> >
> >> Sounds good. And a way to detect appropriate devices could
> >> be by looking at the feature flag, perhaps?
> >
> > Again, no! The way to detect that is to look into the iommu description
> > structures provided by the firmware. They provide everything necessary
> > to tell the iommu code which devices are not translated.
> >
>
> Except on PPC and SPARC. As far as I know, those are the only
> problematic platforms.
>
> Is it too late to *disable* QEMU's q35-iommu thingy until it can be
> fixed to report correct data in the DMAR tables?
>
> --Andy
Meaning virtio or assigned devices?
For virtio - it's way too late since these are working configurations.
For assigned devices - they don't work on x86 so it doesn't have
to be disabled, it's safe to ignore.
--
MST
- [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Michael S. Tsirkin, 2016/04/21
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Wei Liu, 2016/04/21
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, David Woodhouse, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Michael S. Tsirkin, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Joerg Roedel, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Andy Lutomirski, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Andy Lutomirski, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Michael S. Tsirkin, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Joerg Roedel, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Michael S. Tsirkin, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Andy Lutomirski, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Michael S. Tsirkin, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Joerg Roedel, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Michael S. Tsirkin, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, David Woodhouse, 2016/04/27
- Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api, Michael S. Tsirkin, 2016/04/27