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Re: [Qemu-devel] [PATCH] virtio-scsi: finalize IOMMU support
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH] virtio-scsi: finalize IOMMU support |
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Date: |
Wed, 5 Jul 2017 08:27:34 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 |
On 05/07/2017 08:23, Fam Zheng wrote:
>> req->vq = vq;
>> req->dev = s;
>> - qemu_sglist_init(&req->qsgl, DEVICE(s), 8, &address_space_memory);
>> + qemu_sglist_init(&req->qsgl, DEVICE(s), 8, vdev->dma_as);
> Not related to this patch, but is our vIOMMU iotlb implementation safe for
> data
> plane (both virtio-blk and virtio-scsi)? There we don't have BQL to
> synchronize
> between IOVA lookup and update, which means threads can race when accessing
> the
> iotlb GHashTable.
>
> Did I overlook a synchronization mechanism? Or is it missing? Paolo, MST?
I think it's missing. One way to fix it could be to finish the
MemoryRegionCache work and have an IOMMU->virtio notifier, similar to
how vhost works.
Paolo