Re: [PATCH] VT-d: fix device assignment failure (regression from Xen c/s 19805:2f1fa2215e60)

[Weidong Han <weidong.han@intel.com>]

Jan Beulich wrote:
> If the device at <secbus>:00.0 is the device the mapping operation was
> initiated for, trying to map it a second time will fail, and hence
> this second mapping attempt must be prevented (as was done prior to
> said c/s).
>
> Once at it, simplify the code a little, too.
>
> Signed-off-by: Jan Beulich <jbeulich@novell.com>
>
> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -1371,23 +1371,16 @@ static int domain_context_mapping(struct
>          if ( find_upstream_bridge(&bus, &devfn, &secbus) < 1 )
>              break;
>  
> -        /* PCIe to PCI/PCIx bridge */
> -        if ( pdev_type(bus, devfn) == DEV_TYPE_PCIe2PCI_BRIDGE )
> -        {
> -            ret = domain_context_mapping_one(domain, drhd->iommu, bus, devfn);
> -            if ( ret )
> -                return ret;
> +        ret = domain_context_mapping_one(domain, drhd->iommu, bus, devfn);
>  
> -            /*
> -             * Devices behind PCIe-to-PCI/PCIx bridge may generate
> -             * different requester-id. It may originate from devfn=0
> -             * on the secondary bus behind the bridge. Map that id
> -             * as well.
> -             */
> +        /*
> +         * Devices behind PCIe-to-PCI/PCIx bridge may generate different
> +         * requester-id. It may originate from devfn=0 on the secondary bus
> +         * behind the bridge. Map that id as well if we didn't already.
> +         */
> +        if ( !ret && pdev_type(bus, devfn) == DEV_TYPE_PCIe2PCI_BRIDGE &&
> +             (secbus != pdev->bus || pdev->devfn != 0) )
>              ret = domain_context_mapping_one(domain, drhd->iommu, secbus, 0);
> -        }
> -        else /* Legacy PCI bridge */
> -            ret = domain_context_mapping_one(domain, drhd->iommu, bus, devfn);
>  
>          break;
>  
>
>
> Acked-by: Weidong Han <weidong.han@intel.com>
>