Re: [Qemu-devel] [PATCH] virtio: unbreak virtio-pci with IOMMU after caching ring translations

[Michael S. Tsirkin]

On Wed, Mar 01, 2017 at 12:10:40PM +0800, Jason Wang wrote:
> Commit c611c76417f5 ("virtio: add MemoryListener to cache ring
> translations") registers a memory listener to dma_as. This may not
> work when IOMMU is enabled: dma_as(bus_master_as) were initialized in
> pcibus_machine_done() after virtio_realize(). This will cause a
> segfault. Fixing this by using pci_device_iommu_address_space()
> instead to make sure address space were initialized at this time.
> 
> With this fix, IOMMU device were required to be initialized before any
> virtio-pci devices.
> 
> Fixes: c611c76417f5 ("virtio: add MemoryListener to cache ring translations")
> Cc: Paolo Bonzini <address@hidden>
> Signed-off-by: Jason Wang <address@hidden>

This is very ugly. I guess it's better than broken IOMMU ...
Paolo?


> ---
>  hw/virtio/virtio-pci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 5ce42af..b76f3f6 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1153,7 +1153,7 @@ static AddressSpace *virtio_pci_get_dma_as(DeviceState 
> *d)
>      VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
>      PCIDevice *dev = &proxy->pci_dev;
>  
> -    return pci_get_address_space(dev);
> +    return pci_device_iommu_address_space(dev);
>  }
>  
>  static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,
> -- 
> 2.7.4