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Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu
From: |
Alex Williamson |
Subject: |
Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu |
Date: |
Thu, 26 Jul 2012 09:09:37 -0600 |
On Wed, 2012-07-25 at 11:03 -0600, Alex Williamson wrote:
> This adds PCI based device assignment to Qemu using the Linux VFIO
> userspace driver interface. After setting up VFIO device access,
> devices can be added to Qemu guests using the vfio-pci device
> option:
>
> -device vfio-pci,host=1:10.1,id=net0
>
> or for hotplug:
>
> (qemu) device_add vfio-pci,host=1:10.1,id=net0
> (qemu) device_del net0
>
> This patch adds support for assigning host physical PCI devices,
> with or without KVM[1] for x86 hosts and guests. Support for
> POWER hosts and guests is working and expected to follow shortly.
> Other platforms wishing to make use of this need to do the following:
> - Add a VFIO IOMMU interface to the host kernel driver or make us of
> an existing one if possible (pre-req: linux host IOMMU support)
> - Add corresponding mapping calls for your IOMMU in qemu, see
> x86 and POWER for examples.
>
> And if you care about PCI legacy interrupts:
> - Add support for EOI notification (TBD for everyone)
>
> While not requiring KVM support, VFIO based device assignment still
> supports acceleration through KVM. MMIO regions with sufficient
> alignment are mapped directly into the guest addres space and
> platforms supporting direct interrupt injection through eventfds can
> bypass Qemu userspace. This support is included and automatically
> enabled when KVM and KVM irqchip is enabled. These allow VFIO
> based assignment to meet the same performance levels as KVM based
> assignment in the qemu-kvm tree.
>
> Sending this as an RFC for review as we're waiting on VFIO to be
> accepted into the Linux kernel. I'm hoping it will be accepted
> for Linux v3.6. Pending Linux VFIO acceptance, I'd like to get
> this support in for 1.2 and work on generic Qemu EOI infrastructure
> in-tree. This patch is based on current qemu.git merged with MST's
> latest pull request. Thanks,
>
> Alex
>
> [1] The proposed level IRQFD/EOIFD KVM interface is currently
> required to support legacy PCI INTx interrupts. Qemu support for
> this is included here. Qemu infrastructure for EOI notification
> is not yet in place to do this without KVM. Device which rely only
> on MSI/MSIX work in unaccelerated Qemu.
I forgot to mention that anyone wanting to test this out can use the
vfio-for-qemu branch of my git tree here:
git://github.com/awilliam/qemu-vfio.git
Thanks,
Alex
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, (continued)
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Alex Williamson, 2012/07/25
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Avi Kivity, 2012/07/26
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Alex Williamson, 2012/07/26
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Avi Kivity, 2012/07/26
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Alex Williamson, 2012/07/26
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Avi Kivity, 2012/07/26
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Alex Williamson, 2012/07/26
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Avi Kivity, 2012/07/26
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Alex Williamson, 2012/07/26
- Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Avi Kivity, 2012/07/26
Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu,
Alex Williamson <=
Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Avi Kivity, 2012/07/26
Re: [Qemu-devel] [RFC PATCH] vfio: VFIO PCI driver for Qemu, Blue Swirl, 2012/07/27