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Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devic
From: |
Alex Williamson |
Subject: |
Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices |
Date: |
Wed, 20 May 2020 10:46:12 -0600 |
On Wed, 20 May 2020 19:10:07 +0530
Kirti Wankhede <address@hidden> wrote:
> On 5/20/2020 8:25 AM, Yan Zhao wrote:
> > On Tue, May 19, 2020 at 10:58:04AM -0600, Alex Williamson wrote:
> >> Hi folks,
> >>
> >> My impression is that we're getting pretty close to a workable
> >> implementation here with v22 plus respins of patches 5, 6, and 8. We
> >> also have a matching QEMU series and a proposal for a new i40e
> >> consumer, as well as I assume GVT-g updates happening internally at
> >> Intel. I expect all of the latter needs further review and discussion,
> >> but we should be at the point where we can validate these proposed
> >> kernel interfaces. Therefore I'd like to make a call for reviews so
> >> that we can get this wrapped up for the v5.8 merge window. I know
> >> Connie has some outstanding documentation comments and I'd like to make
> >> sure everyone has an opportunity to check that their comments have been
> >> addressed and we don't discover any new blocking issues. Please send
> >> your Acked-by/Reviewed-by/Tested-by tags if you're satisfied with this
> >> interface and implementation. Thanks!
> >>
> > hi Alex and Kirti,
> > after porting to qemu v22 and kernel v22, it is found out that
> > it can not even pass basic live migration test with error like
> >
> > "Failed to get dirty bitmap for iova: 0xca000 size: 0x3000 err: 22"
> >
>
> Thanks for testing Yan.
> I think last moment change in below cause this failure
>
> https://lore.kernel.org/kvm/address@hidden/
>
> > if (dma->iova > iova + size)
> > break;
>
> Surprisingly with my basic testing with 2G sys mem QEMU didn't raise
> abort on g_free, but I do hit this with large sys mem.
> With above change, that function iterated through next vfio_dma as well.
> Check should be as below:
>
> - if (dma->iova > iova + size)
> + if (dma->iova > iova + size -1)
Or just:
if (dma->iova >= iova + size)
Thanks,
Alex
> break;
>
> Another fix is in QEMU.
> https://lists.gnu.org/archive/html/qemu-devel/2020-05/msg04751.html
>
> > > + range->bitmap.size = ROUND_UP(pages, 64) / 8;
> >
> > ROUND_UP(npages/8, sizeof(u64))?
> >
>
> If npages < 8, npages/8 is 0 and ROUND_UP(0, 8) returns 0.
>
> Changing it as below
>
> - range->bitmap.size = ROUND_UP(pages / 8, sizeof(uint64_t));
> + range->bitmap.size = ROUND_UP(pages, sizeof(__u64) *
> BITS_PER_BYTE) /
> + BITS_PER_BYTE;
>
> I'm updating patches with these fixes and Cornelia's suggestion soon.
>
> Due to short of time I may not be able to address all the concerns
> raised on previous versions of QEMU, I'm trying make QEMU side code
> available for testing for others with latest kernel changes. Don't
> worry, I will revisit comments on QEMU patches. Right now first priority
> is to test kernel UAPI and prepare kernel patches for 5.8
>
> Thanks,
> Kirti
>
- Re: [PATCH Kernel v22 6/8] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap, (continued)
[PATCH Kernel v22 7/8] vfio iommu: Add migration capability to report supported features, Kirti Wankhede, 2020/05/18
[PATCH Kernel v22 8/8] vfio: Selective dirty page tracking if IOMMU backed device pins pages, Kirti Wankhede, 2020/05/18
Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices, Alex Williamson, 2020/05/19
- Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices, Yan Zhao, 2020/05/19
- Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices, Kirti Wankhede, 2020/05/20
- Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices,
Alex Williamson <=
- Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices, Yan Zhao, 2020/05/21
- Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices, Kirti Wankhede, 2020/05/21
- Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices, Yan Zhao, 2020/05/21
- Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices, Kirti Wankhede, 2020/05/21
- Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices, Kirti Wankhede, 2020/05/21
Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices, Yan Zhao, 2020/05/25