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Re: [Qemu-devel] [RFC patch 0/6] vfio based pci pass-through for qemu/KV
From: |
Alex Williamson |
Subject: |
Re: [Qemu-devel] [RFC patch 0/6] vfio based pci pass-through for qemu/KVM on s390 |
Date: |
Mon, 22 Sep 2014 14:47:31 -0600 |
On Fri, 2014-09-19 at 13:54 +0200, address@hidden wrote:
> This set of patches implements a vfio based solution for pci
> pass-through on the s390 platform. The kernel stuff is pretty
> much straight forward, but qemu needs more work.
>
> Most interesting patch is:
> vfio: make vfio run on s390 platform
>
> I hope Alex & Alex can give me some guidance how to do the changes
> in an appropriate way. After creating a separate iommmu address space
> for each attached PCI device I can successfully run the vfio type1
> iommu. So If we could extend type1 not registering all guest memory
> (see patch) I think we do not need a special vfio iommu for s390
> for the moment.
>
> The patches implement the base pass-through support. s390 specific
> virtualization functions are currently not included. This would
> be a second step after the base support is done.
>
> kernel patches apply to linux-kvm-next
>
> KVM: s390: Enable PCI instructions
> iommu: add iommu for s390 platform
> vfio: make vfio build on s390
>
> qemu patches apply to qemu-master
>
> s390: Add PCI bus support
> s390: implement pci instruction
> vfio: make vfio run on s390 platform
>
> Thx for feedback and review comments
Sending patches as attachments makes it difficult to comment inline.
2/6
- careful of the namespace as you're changing functions from static and
exporting them
- doesn't seem like functions need to be exported, just non-static to
call from s390-iommu.c
6/6
- We shouldn't need to globally disable mmap, each VFIO region reports
whether it supports mmap and vfio-pci on s390 should indicate mmap is
not supported on the platform.
- INTx should be done the same way, the interrupt index for INTx should
report 0 count. The current code likely doesn't handle this, but it
should be easy to fix.
- s390_msix_notify() vs msix_notify() should be abstracted somewhere
else. How would an emulated PCI device with MSI-X support work?
- same for add_msi_route
- We can probably come up with a better way to determine which address
space to connect to the memory listener.
Looks like a reasonable first pass, good re-use of vfio code. Thanks,
Alex
- [Qemu-devel] [RFC patch 0/6] vfio based pci pass-through for qemu/KVM on s390, frank . blaschka, 2014/09/19
- [Qemu-devel] [RFC patch 3/6] vfio: make vfio build on s390, frank . blaschka, 2014/09/19
- [Qemu-devel] [RFC patch 1/6] KVM: s390: Enable PCI instructions, frank . blaschka, 2014/09/19
- [Qemu-devel] [RFC patch 6/6] vfio: make vfio run on s390 platform, frank . blaschka, 2014/09/19
- [Qemu-devel] [RFC patch 2/6] iommu: add iommu for s390 platform, frank . blaschka, 2014/09/19
- [Qemu-devel] [RFC patch 5/6] s390: implement pci instruction, frank . blaschka, 2014/09/19
- [Qemu-devel] [RFC patch 4/6] s390: Add PCI bus support, frank . blaschka, 2014/09/19
- Re: [Qemu-devel] [RFC patch 0/6] vfio based pci pass-through for qemu/KVM on s390,
Alex Williamson <=
- Re: [Qemu-devel] [RFC patch 0/6] vfio based pci pass-through for qemu/KVM on s390, Frank Blaschka, 2014/09/24