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Diffstat (limited to 'include/uapi/linux/iommufd.h')
| -rw-r--r-- | include/uapi/linux/iommufd.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h index c218c89e0e2e..2c41920b641d 100644 --- a/include/uapi/linux/iommufd.h +++ b/include/uapi/linux/iommufd.h @@ -450,6 +450,16 @@ struct iommu_hwpt_vtd_s1 { * nested domain will translate the same as the nesting parent. The S1 will * install a Context Descriptor Table pointing at userspace memory translated * by the nesting parent. + * + * It's suggested to allocate a vDEVICE object carrying vSID and then re-attach + * the nested domain, as soon as the vSID is available in the VMM level: + * + * - when Cfg=translate, a vDEVICE must be allocated prior to attaching to the + * allocated nested domain, as CD/ATS invalidations and vevents need a vSID. + * - when Cfg=bypass/abort, a vDEVICE is not enforced during the nested domain + * attachment, to support a GBPA case where VM sets CR0.SMMUEN=0. However, if + * VM sets CR0.SMMUEN=1 while missing a vDEVICE object, kernel would fail to + * report events to the VM. E.g. F_TRANSLATION when guest STE.Cfg=abort. */ struct iommu_hwpt_arm_smmuv3 { __aligned_le64 ste[2]; |