Re: [PATCH v5 6/6] VT-d: support the device IOTLB

[David Woodhouse <dwmw2@infradead.org>]

On Mon, 2009-05-18 at 13:51 +0800, Yu Zhao wrote:
> 
> +static struct device_domain_info *iommu_support_dev_iotlb(
> +       struct dmar_domain *domain, int segment, u8 bus, u8 devfn)
> +{
> +       int found = 0;
> +       unsigned long flags;
> +       struct device_domain_info *info;
> +       struct intel_iommu *iommu = device_to_iommu(segment, bus,
> devfn);
> +
> +       if (!ecap_dev_iotlb_support(iommu->ecap))
> +               return NULL;
> +
> +       if (!iommu->qi)
> +               return NULL;
> +
> +       spin_lock_irqsave(&device_domain_lock, flags);
> +       list_for_each_entry(info, &domain->devices, link)
> +               if (info->bus == bus && info->devfn == devfn) {
> +                       found = 1;
> +                       break;
> +               }
> +       spin_unlock_irqrestore(&device_domain_lock, flags);

What if there's more than one device? You only enable ATS for the first
device that supports it, and ignore the others?

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@intel.com                              Intel Corporation