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TTBR1_EL2 mmu translation information wrong when E2H=1

lemin9538

I am now using DS5-studio to debug VHE feature, I set the page table of TTBR0_EL2 and TTBR1_EL2 to the same address, but from the mmu information of DS, they are not same, the memory type is not the same, the information from TTBR0_EL2 is right. It is some wrong in DS studio or there some thing I am missing when set the page table?

mmu information

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  • 0 in reply to Ronan Synnott

    HI Ronan,

    Thanks for you quick response.

    Actually I am using the arm-development-studio now. I am now developing a hypervisor (https://github.com/minosproject/minos), the hypervisor can  work well with ARMv8.0, and I need to enable the hypervisor on A76 SOC with VHE support. some register setting showed as below:

    HCR_EL2.VHE = 1

    SCTLR_EL2 = 0x30c50838

    TCR_EL2 = 0x25B5103510

    MAIR_EL2 = 0xff440c0400

    After I create the page table, TTBR0_EL2 (mapping information is right) and TTBR1_EL2(mapping information is wrong) show different result as I mentioned in the last post, the memory type from the TTBR1_EL2 is wrong.

    Thanks

    Le Min

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  • 0 in reply to Ronan Synnott

    HI Ronan,

    Thanks for you quick response.

    Actually I am using the arm-development-studio now. I am now developing a hypervisor (https://github.com/minosproject/minos), the hypervisor can  work well with ARMv8.0, and I need to enable the hypervisor on A76 SOC with VHE support. some register setting showed as below:

    HCR_EL2.VHE = 1

    SCTLR_EL2 = 0x30c50838

    TCR_EL2 = 0x25B5103510

    MAIR_EL2 = 0xff440c0400

    After I create the page table, TTBR0_EL2 (mapping information is right) and TTBR1_EL2(mapping information is wrong) show different result as I mentioned in the last post, the memory type from the TTBR1_EL2 is wrong.

    Thanks

    Le Min

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  • +1 Arm Employee Badge in reply to lemin9538
    Hi Le Min
    I can reproduce what you see for a simple example.

    This does look like a problem with the Arm DS Debugger's decoding of Memory Types for the case where VHE is enabled:
    HCR_EL2.E2H = 1
    HCR_EL2.TGE = 1
    I have reported this to our Development Team for further investigation. 
    In the meantime, does your code execute as expected?
    Stephen
  • 0 in reply to Stephen Theobald

    Hi Stephen,

    Good to know that. Thanks.

    My code runs good under ARMv8.0, But when I enable VHE (HCR_EL2.E2H = 1), The Guest VM can not boot successfully, and the Guest Linux will hang with access a strange address, so currently I am not sure whether this is caused by my hypervisor code or caused by the DS studio.

    Thanks

    Le Min