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Arm System Memory Management Unit Architecture Specification Arm® System Memory Management Unit Architecture Specification SMMU architecture version 3 Document number ARM IHI 0070 Document version D.a Document confidentiality Non-confidential Copyright © 2016-2020 Arm Limited or its affiliates. All rights reserved. Arm System Memory Management Unit Architecture Specifica- tion Release information Date Version Changes 2020/Aug/31 D.a• Update with SMMUv3.3 architecture • Amendments and clarifications 2019/Jul/18 C.a• Amendments and clarifications 2018/Mar/16 C• Update with SMMUv3.2 architecture • Further amendments and clarifications 2017/Jun/15 B• Amendments and clarifications 2016/Oct/15 A• First release ii Non-Confidential Proprietary Notice This document is protected by copyright and other related rights and the practice or implementation of the information contained in this document may be protected by one or more patents or pending patent applications. 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Company 02557590 registered in England. 110 Fulbourn Road, Cambridge, England CB1 9NJ. LES-PRE-20349 version 21.0 ARM IHI 0070 Copyright © 2016-2020 Arm Limited or its affiliates. All rights reserved. iii D.a Non-confidential Contents Arm® System Memory Management Unit Architecture Specifi- cation Arm System Memory Management Unit Architecture Specification ............ ii Release information .................................. ii Non-Confidential Proprietary Notice .......................... iii Chapter 1 About this document 1.1 References ..................................... 12 1.2 Terms and abbreviations .............................. 13 1.3 Document Scope .................................. 17 Chapter 2 Introduction 2.1 History ........................................ 20 2.2 SMMUv3.0 features ................................ 21 2.3 SMMUv3.1 features ................................ 23 2.4 SMMUv3.2 features ................................ 24 2.5 SMMUv3.3 features ................................ 25 2.6 Permitted implementation of subsets of SMMUv3.x and SMMUv3.(x+1) archi- tectural features ................................... 26 2.7 System placement ................................. 27 Chapter 3 Operation 3.1 Software interface ................................. 30 3.2 Stream numbering ................................. 32 3.3 Data structures and translation procedure .................... 34 3.3.1 Stream Table lookup ............................ 34 3.3.2 StreamIDs to Context Descriptors ..................... 36 3.3.3 Configuration and Translation lookup ................... 40 3.3.4 Transaction attributes: incoming, two-stage translation and overrides .. 42 3.3.5 Translation table descriptors ........................ 43 3.4 Address sizes .................................... 44 3.4.1 Input address size and Virtual Address size ................ 46 3.4.2 Address alignment checks ......................... 47 3.4.3 Address sizes of SMMU-originated accesses ............... 47 3.5 Command and Event queues ........................... 50 3.5.1 SMMU circular queues ........................... 50 3.5.2 Queue entry visibility semantics ...................... 53 3.5.3 Event queue behavior ............................ 53 3.5.4 Definition of event record write “Commit” ................. 54 3.5.5 Event merging ................................ 54 3.5.6 Enhanced Command queue interfaces .................. 55 3.6 Structure and queue ownership .......................... 58 3.7 Programming registers ............................... 59 3.8 Virtualization .................................... 60 3.9 Support for PCI Express, PASIDs, PRI and ATS ................. 61 3.9.1 ATS Interface ................................ 61 3.9.2 Changing ATS configuration ........................ 68 3.9.3 SMMU interactions with CXL ........................ 69 3.10 Support for two Security states .......................... 70 ARM IHI 0070 Copyright © 2016-2020 Arm Limited or its affiliates. All rights reserved. iv D.a Non-confidential Contents 3.10.1 Secure State Determination (SSD) .................... 70 3.10.2 Secure commands, events and configuration ............... 71 3.10.3 Secure EL2 and support for Secure stage 2 translation ......... 73 3.11 Reset, Enable and initialization .......................... 75 3.12 Fault models, recording and reporting ....................... 78 3.12.1 Terminate model .............................. 80 3.12.2 Stall model .................................. 81 3.12.3 Considerations for client devices using the Stall fault model ....... 84 3.12.4 Virtual Memory paging with SMMU .................... 84 3.12.5 Combinations of fault configuration with two stages ........... 85 3.13 Translation table entries and Access/Dirty flags ................. 87 3.13.1 Software update of flags .......................... 87 3.13.2 Access flag hardware update ........................ 88 3.13.3 Dirty flag hardware update ......................... 88 3.13.4 HTTU behavior summary .......................... 89 3.13.5 HTTU with two stages of translation .................... 90 3.13.6 ATS, PRI and translation table flag update ................ 91 3.13.7 Hardware flag update for Cache Maintenance Operations and Destruc- tive Reads .................................. 92 3.14 Speculative accesses ............................... 93 3.15 Coherency considerations and memory access types .............. 94 3.15.1 Client devices ................................ 94 3.16 Embedded implementations ............................ 96 3.16.1 Changes to structure and queue storage behavior when fixed/preset .. 96 3.17 TLB tagging, VMIDs, ASIDs and participation in broadcast TLB maintenance . 98 3.17.1 The Global flag in the Translation Table Descriptor ............ 100 3.17.2 Broadcast TLB maintenance from Armv8-A PEs with EL3 in AArch64 . 101 3.17.3 Broadcast TLB maintenance from ARMv7-A PEs or Armv8-A PEs with EL3 using AArch32 ............................. 102 3.17.4 Broadcast TLB maintenance in mixed AArch32 and AArch64 systems and with mixed ASID or VMID sizes .................... 102 3.17.5 EL2 ASIDs and TLB maintenance in EL2 Host (E2H) mode ....... 103 3.17.6 VMID Wildcards ............................... 104 3.18 Interrupts and notifications ............................. 106 3.18.1 MSI synchronization ............................ 107 3.18.2 Interrupt sources .............................. 107 3.19 Power control .................................... 109 3.19.1 Dormant state ................................ 109 3.20 TLB and configuration cache conflict ....................... 110 3.20.1 TLB conflict ................................. 110 3.20.2 Configuration cache conflicts ........................ 110 3.21 Structure access rules and update procedures .................. 112 3.21.1 Translation tables and TLB invalidation completion behavior ....... 112 3.21.2 Queues ................................... 115 3.21.3 Configuration structures and configuration invalidation completion
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