Re: [Qemu-devel] [Qemu-arm] [PATCH v3 0/2] virtio-iommu: VFIO integration

[Linu Cherian]

Hi,

On Mon Aug 21, 2017 at 04:18:52PM +0530, Bharat Bhushan wrote:
> This V3 version is mainly about rebasing on v3 version on Virtio-iommu device
> framework from Eric Augur and addresing review comments.
> 
> This patch series allows PCI pass-through using virtio-iommu.
>   
> This series is based on:
>  - virtio-iommu specification written by Jean-Philippe Brucker
>    [RFC 0/3] virtio-iommu: a paravirtualized IOMMU,
>  
>  - virtio-iommu driver by Jean-Philippe Brucker
>    [RFC PATCH linux] iommu: Add virtio-iommu driver
>  
>  - virtio-iommu device emulation by Eric Augur.
>    [RFC v3 0/8] VIRTIO-IOMMU device
> 
> PCI device pass-through and virtio-net-pci is tested with these changes using 
> dma-ops
> 

Facing issues while trying to test with VFIO.

vfio_dma_map fails as below, 
qemu-system-aarch64: vfio_dma_map(0x1ff0da0, 0xfdfc7000, 0x1000, 
0xffff79acc000) = -22 (Invalid argument)
Very likely this seem to be an issue with map size. Kernel PAGE_SIZE 
is 64k on my host and hence the map size for the physical SMMU also will
start with 64k. 

Qemu source: https://github.com/eauger/qemu.git + this patch series
             on branch v2.10.0-rc0-virtio-iommu-rfcv3
Linux source: git://linux-arm.org/linux-jpb.git
             on branch virtio-iommu/v0.1
Any pointers ?

The other related questions i had,
1.  In, virtio_iommu_device_realize in qemu,
   s->config.page_sizes = TARGET_PAGE_MASK;

  Same is being taken as pgsize_bitmap in virtio_iommu guest kernel driver.
  In, viommu_probe 
  virtio_cread(vdev, struct virtio_iommu_config, page_sizes,
                     &viommu->pgsize_bitmap);

  Should s->config.page_sizes be initialized with page bitmap instead
  of page mask ?

2. Should we not populate the supported page sizes based on  
   host kernel size and SMMU hardware capability rather than 
   based on the machine emulated on qemu? Atleast that makes
   sense for VFIO case.

> This patch series does not implement RESV_MEM changes proposal by 
> Jean-Philippe 
> "https://lists.gnu.org/archive/html/qemu-devel/2017-07/msg01796.html";
> 
> v2->v3:
>  - This series is based on "[RFC v3 0/8] VIRTIO-IOMMU device"
>    Which is based on top of v2.10-rc0 that 
>  - Fixed issue with two PCI devices
>  - Addressed review comments
> 
> v1->v2:
>   - Added trace events
>   - removed vSMMU3 link in patch description
> 
> Bharat Bhushan (2):
>   target/arm/kvm: Translate the MSI doorbell in kvm_arch_fixup_msi_route
>   virtio-iommu: vfio integration with virtio-iommu
> 
>  hw/virtio/trace-events           |   5 ++
>  hw/virtio/virtio-iommu.c         | 163 
> +++++++++++++++++++++++++++++++++++++++
>  include/hw/virtio/virtio-iommu.h |   6 ++
>  target/arm/kvm.c                 |  27 +++++++
>  target/arm/trace-events          |   3 +
>  5 files changed, 204 insertions(+)
> 
> -- 
> 1.9.3
> 
> 

-- 
Linu cherian