Messages in this thread | | | Subject | Re: [PATCH v5 2/8] iommu/vt-d: Add per-device IOMMU feature ops entries | From | Lu Baolu <> | Date | Thu, 24 Jan 2019 14:47:39 +0800 |
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Hi Joerg,
On 1/11/19 7:16 PM, Joerg Roedel wrote: >> + >> +static bool >> +intel_iommu_dev_has_feat(struct device *dev, enum iommu_dev_features feat) >> +{ >> + struct device_domain_info *info = dev->archdata.iommu; >> + >> + if (feat == IOMMU_DEV_FEAT_AUX) >> + return scalable_mode_support() && info && info->auxd_enabled; >> + >> + return false; >> +} > Why is this checking the auxd_enabled flag? The function should just > return whether the device_supports_ scalable mode, not whether it is > enabled.
Yes, as the API name implies, it should return the device capability instead of enable/disable status. I misused this API in the IOMMU driver.
Since we already have iommu_dev_enable/disable_feature() to enable and disable an iommu specific feature, is it possible to add another API to query whether a specific feature has been enabled?
How about
bool iommu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX)?
This is necessary for the third party drivers (like vfio) to determine which domain attach interface it should use:
if (iommu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX)) iommmu_aux_attach_device(domain, dev) else iommu_attach_device(domain, dev)
Best regards, Lu Baolu
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