Question about SMMU tests (again)

[hrw]

When Secure-EL2 is implemented, B_SMMU_08, B_SMMU_16, B_SMMU_17, B_SMMU_18 tests (304, 352) are skipped.

For B_SMMU_08 BSA 1.0C says:

If Secure-EL2 is not implemented, stage 1 System MMU functionality that is made visible to an operating system must present the interface of a System MMU compatible with one of the following:

• The SMMUv2 specification, where each context bank must present a unique physical interrupt to the GIC.
• The Arm SMMUv3 specification or higher, where the integration of the System MMUs is compliant with the requirements in Section D.

And B_SMMU_16:

If a device is assigned and passed through to an operating system under a hypervisor, then the memory transactions of the device must be subject to stage 2 translation, allocation of memory attributes, and application of permission checks, under the control of the hypervisor. This specification collectively refers to this translation, attribution, and permission checking as policing. The act of policing is called stage 2 System MMU functionality.

B_SMMU_17:

From a hardware perspective, this means that a base system supporting a protection hypervisor requires all non-secure DMA capable devices that will be assigned to a non-secure VM for direct control to be policed by stage 2 System MMU functionality.

B_SMMU_18:

If Secure-EL2 is not implemented, stage 2 System MMU functionality must be provided by a System MMU compatible with the Arm SMMUv2 specification or Arm SMMUv3 specification.

I start to wonder which stage functionality is required when Secure-EL2 is implemented.

Would say that stage1 due to _08 and stage2 due to _16/17 but ACS do not check for any of them when SEL2 is enabled.

[chetan-rathore]

Hello @hrw,

Thanks for the query, it did lead to a good discussion on our side.

For the main intent of your query "When S-EL2 is enabled, how the stage1 and stage 2 SMMU requirements are checked in BSA-ACS"

BSA does not mandate either Stage 1 or Stage 2 but does mandate certain requirements if these are supported. If Secure-EL2 is implemented then an SMMUv3.2 is supported, which implies that both SMMU Stage 1 and Stage 2 are implemented. In this case, rule B_SMMU_21 applies for BSA.

Also, the BSA test for B_SMMU_08/18, should also include the SMMU version check when PE supports S-EL2.

Thanks, Chetan

[chetan-rathore]

Hello @hrw,

Required changes as discussed above are merged in the ACS.

Thanks, ACS team

[hrw]

sbsa-ref with neoverse-n2 on recent QEMU:

      *** Starting SMMU tests ***

Operating System View:
 301 : All SMMUs have same Arch Revision          : Result:  PASS
 302 : Check SMMU Granule Support                 : Result:  PASS
 303 : Check SMMU Large Physical Addr Support
       Checkpoint --  1                           : Result:  SKIPPED
 304 : Check SMMU S-EL2 & stage1 support          : Result:  PASS

Hypervisor View:
 352 : Check SMMU S-EL2 & stage2 support
       SMMUv3.1 not providing Stage2 functionality
       Failed on PE -    0
       Checkpoint --  2                           : Result:  FAIL
 354 : SMMUv3 Integration compliance              : Result:  PASS

      One or more SMMU tests failed or were skipped.

Emulated SMMU v3.1 has either Stage1 or Stage2 but not both at same time. It is one of remaining blockers for SBSA level 3 compliance (looking at (S)BSA ACS test results).

[chetan-rathore]

Hi @hrw,

Please let us know if any further help required for this issue from ACS team.

Thanks, ACS team