CA72 can't access ICC_IAR1_EL1 at EL1

Hmm, interesting.

A few questions then:

• Are you setting up ICC_SRE_EL2.SRE before ICC_SRE_EL1(NS)?
• Do you have ISBs between changing SCR_EL3.NS and accessing the different ICC_SRE_EL1s?
• To which EL is the exception being taken? (I was assuming EL1!)
  • If it's being taken to EL2, you also need to check how ICH_HCR_EL2.TALL1 is configured.
• The Op0/Op1/Op2/CRn/CRm values reported don't match ICC_IAR1_EL1.  Have you sanity checked that's the instruction actually being executed?

Hmm, interesting.

A few questions then:

• Are you setting up ICC_SRE_EL2.SRE before ICC_SRE_EL1(NS)?
• Do you have ISBs between changing SCR_EL3.NS and accessing the different ICC_SRE_EL1s?
• To which EL is the exception being taken? (I was assuming EL1!)
  • If it's being taken to EL2, you also need to check how ICH_HCR_EL2.TALL1 is configured.
• The Op0/Op1/Op2/CRn/CRm values reported don't match ICC_IAR1_EL1.  Have you sanity checked that's the instruction actually being executed?

Hi Martin,

Not sure why my previous reply at last night was flagged by as inappropriate and doesn't appear on the site. But it's back now. 

Could you kindly help to review my previous reply? thanks in advance. 

Ok, that makes sense.  The trap was to EL3, not EL1.

UNDEFINED means you'll take a synchronous exception with a different ESR_ELx.EC code.  The practical difference between a "trap" and UNDEF is that traps are (usually) expected to be recovered from.  You trap the access, do something, and then either re-execute the trapped instruction or emulate it.  With UNDEF, typically the program did something it shouldn't and you'd terminate it.

Hi Martin,

Thanks very much for your great help!!