Messages in this thread | | | Subject | Re: [PATCH] vhost/vsock: add IOTLB API support | From | Jason Wang <> | Date | Tue, 3 Nov 2020 17:04:23 +0800 |
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On 2020/11/3 上午1:11, Stefano Garzarella wrote: > On Fri, Oct 30, 2020 at 07:44:43PM +0800, Jason Wang wrote: >> >> On 2020/10/30 下午6:54, Stefano Garzarella wrote: >>> On Fri, Oct 30, 2020 at 06:02:18PM +0800, Jason Wang wrote: >>>> >>>> On 2020/10/30 上午1:43, Stefano Garzarella wrote: >>>>> This patch enables the IOTLB API support for vhost-vsock devices, >>>>> allowing the userspace to emulate an IOMMU for the guest. >>>>> >>>>> These changes were made following vhost-net, in details this patch: >>>>> - exposes VIRTIO_F_ACCESS_PLATFORM feature and inits the iotlb >>>>> device if the feature is acked >>>>> - implements VHOST_GET_BACKEND_FEATURES and >>>>> VHOST_SET_BACKEND_FEATURES ioctls >>>>> - calls vq_meta_prefetch() before vq processing to prefetch vq >>>>> metadata address in IOTLB >>>>> - provides .read_iter, .write_iter, and .poll callbacks for the >>>>> chardev; they are used by the userspace to exchange IOTLB messages >>>>> >>>>> This patch was tested with QEMU and a patch applied [1] to fix a >>>>> simple issue: >>>>> $ qemu -M q35,accel=kvm,kernel-irqchip=split \ >>>>> -drive file=fedora.qcow2,format=qcow2,if=virtio \ >>>>> -device intel-iommu,intremap=on \ >>>>> -device vhost-vsock-pci,guest-cid=3,iommu_platform=on >>>> >>>> >>>> Patch looks good, but a question: >>>> >>>> It looks to me you don't enable ATS which means vhost won't get any >>>> invalidation request or did I miss anything? >>>> >>> >>> You're right, I didn't see invalidation requests, only miss and >>> updates. >>> Now I have tried to enable 'ats' and 'device-iotlb' but I still >>> don't see any invalidation. >>> >>> How can I test it? (Sorry but I don't have much experience yet with >>> vIOMMU) >> >> >> I guess it's because the batched unmap. Maybe you can try to use >> "intel_iommu=strict" in guest kernel command line to see if it works. >> >> Btw, make sure the qemu contains the patch [1]. Otherwise ATS won't >> be enabled for recent Linux Kernel in the guest. > > The problem was my kernel, it was built with a tiny configuration. > Using fedora stock kernel I can see the 'invalidate' requests, but I > also had the following issues. > > Do they make you ring any bells? > > $ ./qemu -m 4G -smp 4 -M q35,accel=kvm,kernel-irqchip=split \ > -drive file=fedora.qcow2,format=qcow2,if=virtio \ > -device intel-iommu,intremap=on,device-iotlb=on \ > -device vhost-vsock-pci,guest-cid=6,iommu_platform=on,ats=on,id=v1 > > qemu-system-x86_64: vtd_iova_to_slpte: detected IOVA overflow > (iova=0x1d40000030c0)
It's a hint that IOVA exceeds the AW. It might be worth to check whether the missed IOVA reported from IOTLB is legal.
Thanks
> qemu-system-x86_64: vtd_iommu_translate: detected translation failure > (dev=00:03:00, iova=0x1d40000030c0) > qemu-system-x86_64: New fault is not recorded due to compression > of faults > > Guest kernel messages: > [ 44.940872] DMAR: DRHD: handling fault status reg 2 > [ 44.941989] DMAR: [DMA Read] Request device [00:03.0] PASID > ffffffff fault addr ffff88W > [ 49.785884] DMAR: DRHD: handling fault status reg 2 > [ 49.788874] DMAR: [DMA Read] Request device [00:03.0] PASID > ffffffff fault addr ffff88W > > > QEMU: b149dea55c Merge remote-tracking branch > 'remotes/cschoenebeck/tags/pull-9p-20201102' into staging > > Linux guest: 5.8.16-200.fc32.x86_64 > > > Thanks, > Stefano >
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