[PATCH master v2 2/2] mach-k3: enable mmu after reserved memory is unmapped

[Anshul Dalal]

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 (done by mmu_setup)
 3. Enable MMU
 4. Unmap reserved-memory regions
 5. Enable caches

However there is a brief period of execution between #3 and #4 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")
Reported-by: Suhaas Joshi <s-jo...@ti.com>
Signed-off-by: Anshul Dalal <ansh...@ti.com>
---
 arch/arm/mach-k3/common.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/mach-k3/common.c b/arch/arm/mach-k3/common.c
index 396018b7a7a..9bebc0b1106 100644
--- a/arch/arm/mach-k3/common.c
+++ b/arch/arm/mach-k3/common.c
@@ -295,6 +295,7 @@ void enable_caches(void)
                               __func__, ret);
        }
 
+       mmu_enable();
        icache_enable();
        dcache_enable();
 }

-- 
2.53.0