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iommu: Add device ATS supported capability

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PCIe ATS may be disabled by platform firmware, root complex limitations,
or kernel policy even when a device advertises the ATS capability in its
PCI configuration space.

Add a new IOMMU_CAP_PCI_ATS_SUPPORTED capability to allow IOMMU drivers
to report the effective ATS decision for a device.

When this capability is true for a device, ATS may be enabled for that
device, but it does not imply that ATS is currently enabled.

A subsequent patch will extend iommufd to expose the effective ATS
status to userspace.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
This commit is contained in:
Shameer Kolothum 2026-03-17 11:16:02 +00:00 committed by Joerg Roedel
parent d6c65b0fd6
commit a82efb8747
4 changed files with 13 additions and 0 deletions
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6
drivers/iommu/amd/iommu.c
View File

@ -2985,6 +2985,12 @@ static bool amd_iommu_capable(struct device *dev, enum iommu_cap cap)
return amd_iommu_hd_support(iommu);
}
case IOMMU_CAP_PCI_ATS_SUPPORTED: {
struct iommu_dev_data *dev_data = dev_iommu_priv_get(dev);
return amd_iommu_iotlb_sup &&
(dev_data->flags & AMD_IOMMU_DEVICE_FLAG_ATS_SUP);
}
default:
break;
}

3
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
View File

@ -107,6 +107,7 @@ static const char * const event_class_str[] = {
};
static int arm_smmu_alloc_cd_tables(struct arm_smmu_master *master);
static bool arm_smmu_ats_supported(struct arm_smmu_master *master);
static void parse_driver_options(struct arm_smmu_device *smmu)
{
@ -2494,6 +2495,8 @@ static bool arm_smmu_capable(struct device *dev, enum iommu_cap cap)
return true;
case IOMMU_CAP_DIRTY_TRACKING:
return arm_smmu_dbm_capable(master->smmu);
case IOMMU_CAP_PCI_ATS_SUPPORTED:
return arm_smmu_ats_supported(master);
default:
return false;
}

2
drivers/iommu/intel/iommu.c
View File

@ -3220,6 +3220,8 @@ static bool intel_iommu_capable(struct device *dev, enum iommu_cap cap)
return ecap_sc_support(info->iommu->ecap);
case IOMMU_CAP_DIRTY_TRACKING:
return ssads_supported(info->iommu);
case IOMMU_CAP_PCI_ATS_SUPPORTED:
return info->ats_supported;
default:
return false;
}

2
include/linux/iommu.h
View File

@ -272,6 +272,8 @@ enum iommu_cap {
*/
IOMMU_CAP_DEFERRED_FLUSH,
IOMMU_CAP_DIRTY_TRACKING, /* IOMMU supports dirty tracking */
/* ATS is supported and may be enabled for this device */
IOMMU_CAP_PCI_ATS_SUPPORTED,
};
/* These are the possible reserved region types */