Re: [PATCH master] mach-k3: enable mmu after reserved memory is unmapped

[Anshul Dalal <anshuld@ti.com>]

On Tue May 12, 2026 at 4:33 PM IST, Anshul Dalal wrote:
> Currently the sequence to enable caches for the A53/A72 core on K3
> devices looks as follows:
>
>  1. Map entire DDR banks
>  2. Setup page tables and enable MMU (done by mmu_setup)
>  3. Unmap reserved-memory regions
>  4. Enable caches
>
> However there is a brief period of execution between #2 and #3 where the
> core can issue speculative accesses to the entire DDR space (including
> the reserved-memory regions) despite the caches being disabled.
>
> A firewall exception is triggered whenever such speculative access is
> made to secure DDR region of TFA or OP-TEE. This patch fixes the issue
> by re-ordering the sequence as follows:
>
>  1. Map entire DDR banks
>  2. Setup page tables
>  3. Unmap reserved-memory regions
>  4. Enable MMU
>  5. Enable caches
>
> Fixes: f1c694b8fdde ("mach-k3: map all banks using mem_map_from_dram_banks")
> Signed-off-by: Anshul Dalal <anshuld@ti.com>

Forgot to add:

  Reported-by: Suhaas Joshi <s-joshi@ti.com>

--
Anshul Dalal <anshuld@ti.com>