[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings
From: |
Benjamin Herrenschmidt |
Subject: |
Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings |
Date: |
Tue, 23 Aug 2011 06:53:46 +1000 |
On Mon, 2011-08-22 at 09:30 +0300, Avi Kivity wrote:
> On 08/20/2011 07:51 PM, Alex Williamson wrote:
> > We need to address both the description and enforcement of device
> > groups. Groups are formed any time the iommu does not have resolution
> > between a set of devices. On x86, this typically happens when a
> > PCI-to-PCI bridge exists between the set of devices and the iommu. For
> > Power, partitionable endpoints define a group. Grouping information
> > needs to be exposed for both userspace and kernel internal usage. This
> > will be a sysfs attribute setup by the iommu drivers. Perhaps:
> >
> > # cat /sys/devices/pci0000:00/0000:00:19.0/iommu_group
> > 42
> >
>
> $ readlink /sys/devices/pci0000:00/0000:00:19.0/iommu_group
> ../../../path/to/device/which/represents/the/resource/constraint
>
> (the pci-to-pci bridge on x86, or whatever node represents partitionable
> endpoints on power)
The constraint might not necessarily be a device.
The PCI bridge is just an example. There are other possible constraints.
On POWER for example, it could be a limit in how far I can segment the
DMA address space, forcing me to arbitrarily put devices together, or it
could be a similar constraint related to how the MMIO space is broken
up.
So either that remains a path in which case we do have a separate set of
sysfs nodes representing the groups themselves which may or may not
itself contain a pointer to the "constraining" device, or we just make
that an arbitrary number (in my case the PE#)
Cheers,
Ben
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, (continued)
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Avi Kivity, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Joerg Roedel, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Avi Kivity, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Roedel, Joerg, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Avi Kivity, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Roedel, Joerg, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Avi Kivity, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Roedel, Joerg, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Avi Kivity, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Roedel, Joerg, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings,
Benjamin Herrenschmidt <=
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Joerg Roedel, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Alex Williamson, 2011/08/22
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Roedel, Joerg, 2011/08/23
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Alex Williamson, 2011/08/23
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Roedel, Joerg, 2011/08/24
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Alex Williamson, 2011/08/24
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Roedel, Joerg, 2011/08/25
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Alexander Graf, 2011/08/25
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, David Gibson, 2011/08/26
- Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings, Roedel, Joerg, 2011/08/26