Re: [Xen-devel] [PATCH v2] IOMMU: Prevent VT-d device IOTLB operations on wrong IOMMU

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.06.14 at 14:28, <malcolm.crossley@xxxxxxxxxx> wrote:
> Optimised AMD's IOMMU code by leveraging the new IOMMU field in the ATS
> structure.

This optimization should presumably be dropped after having done
the constification:

> --- a/xen/drivers/passthrough/amd/iommu_cmd.c
> +++ b/xen/drivers/passthrough/amd/iommu_cmd.c
> @@ -303,8 +303,7 @@ void amd_iommu_flush_iotlb(u8 devfn, con
>      if ( !pci_ats_enabled(ats_pdev->seg, ats_pdev->bus, ats_pdev->devfn) )
>          return;
>  
> -    iommu = find_iommu_for_device(ats_pdev->seg,
> -                                  PCI_BDF2(ats_pdev->bus, ats_pdev->devfn));
> +    iommu = (struct amd_iommu *) ats_pdev->iommu;

Casts like this are ugly and error prone (leaving aside that it violates
the promises "const" makes).

> @@ -34,7 +35,7 @@ struct pci_ats_dev {
>  extern struct list_head ats_devices;
>  extern bool_t ats_enabled;
>  
> -int enable_ats_device(int seg, int bus, int devfn);
> +int enable_ats_device(void *iommu, int seg, int bus, int devfn);

The first parameter should now be "const" too.

Jan


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