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Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to
From: |
Avi Kivity |
Subject: |
Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA |
Date: |
Sun, 16 Oct 2011 15:15:53 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:7.0) Gecko/20110927 Thunderbird/7.0 |
On 10/14/2011 04:14 AM, David Gibson wrote:
> > Virtio is a very, very special case. virtio requires coherent RAM access.
>
> Right. Virtio's access to memory is *not* emulated PCI DMA, it's
> god-like hypervisor access to guest system memory. It should
> correctly bypass any IOMMU, and so should remain as
> cpu_physical_memory_rw() or the atomic accessors, rather than being
> converted to this new API.
virtio should definitely not bypass an iommu. A guest may assign a
virtio device to nested guests, and would wish it confined by the
emulated iommu.
More generally, a guest sees a virtio device as just another pci device,
and has no way to tell that it bypasses the iommu.
--
error compiling committee.c: too many arguments to function
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, (continued)
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, Avi Kivity, 2011/10/02
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, Michael S. Tsirkin, 2011/10/02
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, Avi Kivity, 2011/10/02
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, Anthony Liguori, 2011/10/03
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, David Gibson, 2011/10/11
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, Michael S. Tsirkin, 2011/10/12
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, David Gibson, 2011/10/13
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, Michael S. Tsirkin, 2011/10/16
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA,
Avi Kivity <=
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, David Gibson, 2011/10/17
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, Michael S. Tsirkin, 2011/10/18
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, Rusty Russell, 2011/10/18
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, Avi Kivity, 2011/10/19
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, David Gibson, 2011/10/19
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, David Gibson, 2011/10/11
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, Michael S. Tsirkin, 2011/10/12
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, David Gibson, 2011/10/12
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, David Gibson, 2011/10/12
- Re: [Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA, David Gibson, 2011/10/11