*** Bug 1539256 has been marked as a duplicate of this bug. ***

Are you sure the problem is with iommu driver? It looks from the screenshot that Windows is looking for the storage driver. Did you try to install the virtio-block driver from CD?

The failure is due to iommu_platform=on command line flag that enables the usage of VIRTIO_F_IOMMU_PLATFORM virtio device flag. virtio-win drivers don't acknowledge VIRTIO_F_IOMMU_PLATFORM.

(In reply to Yan Vugenfirer from comment #5)
> The failure is due to iommu_platform=on command line flag that enables the
> usage of VIRTIO_F_IOMMU_PLATFORM virtio device flag. virtio-win drivers
> don't acknowledge VIRTIO_F_IOMMU_PLATFORM.

I think it fails because of below check in virtio_validate_features:

static int virtio_validate_features(VirtIODevice *vdev)
{
    VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);

    if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM) &&
        !virtio_vdev_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) {
        return -EFAULT;
    }

    if (k->validate_features) {
        return k->validate_features(vdev);
    } else {
        return 0;
    }
}

This check was added by Jason:

commit 8607f5c3072caeebbe0217df28651fffd3a79fd9
Author: Jason Wang <jasowang>
Date:   Fri Dec 30 18:09:10 2016 +0800

    virtio: convert to use DMA api
    
    Currently, all virtio devices bypass IOMMU completely. This is because
    address_space_memory is assumed and used during DMA emulation. This
    patch converts the virtio core API to use DMA API. This idea is
    
    - introducing a new transport specific helper to query the dma address
      space. (only pci version is implemented).
    - query and use this address space during virtio device guest memory
      accessing when iommu platform (VIRTIO_F_IOMMU_PLATFORM) was enabled
      for this device.
    
    Cc: Michael S. Tsirkin <mst>
    Cc: Stefan Hajnoczi <stefanha>
    Cc: Kevin Wolf <kwolf>
    Cc: Amit Shah <amit.shah>
    Cc: Paolo Bonzini <pbonzini>
    Cc: qemu-block
    Signed-off-by: Jason Wang <jasowang>
    Reviewed-by: Michael S. Tsirkin <mst>
    Signed-off-by: Michael S. Tsirkin <mst>


Adding Michael & Jason in cc:

Regards,
Maxime

https://github.com/virtio-win/kvm-guest-drivers-windows/pull/261

Hi Yan,

Similar confuse with the bug 1539256(for vioscsi), I tested this issue(for viostor) with virtio-win-prewhql-150 on win2012-r2 and win2016.

on win2016, cannot reproduce this issue.
on win2012-r2, can reproduce this issue.

Could please help to confirm if the virtio-win for iommu feature only supported on win2016 and win10~ 


Thanks a lot~

(In reply to Peixiu Hou from comment #8)
> Hi Yan,
> 
> Similar confuse with the bug 1539256(for vioscsi), I tested this issue(for
> viostor) with virtio-win-prewhql-150 on win2012-r2 and win2016.
> 
> on win2016, cannot reproduce this issue.
> on win2012-r2, can reproduce this issue.
> 
> Could please help to confirm if the virtio-win for iommu feature only
> supported on win2016 and win10~ 
> 
> 
> Thanks a lot~


Hi,

Yes - it is supported only for Windows 10, Windows 2016 and up.

Best regards.

Thanks for confirm~
Thus this issue is fixed on virtio-win-prewhql-150, change this bug to verified, thanks a lot~

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2018:3413