[PATCH master v3 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-joshi at ti.com>
Signed-off-by: Anshul Dalal <anshuld at ti.com>
---
 arch/arm/mach-k3/common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mach-k3/common.c b/arch/arm/mach-k3/common.c
index 396018b7a7a..19a6e24f38b 100644
--- a/arch/arm/mach-k3/common.c
+++ b/arch/arm/mach-k3/common.c
@@ -279,7 +279,6 @@ void enable_caches(void)
 		       __func__, fdt_strerror(ret));
 
 	mmu_setup();
-	mmu_enable();
 
 	if (CONFIG_K3_ATF_LOAD_ADDR >= CFG_SYS_SDRAM_BASE) {
 		ret = mmu_unmap_reserved_mem("tfa", true);
@@ -295,6 +294,7 @@ void enable_caches(void)
 			       __func__, ret);
 	}
 
+	mmu_enable();
 	icache_enable();
 	dcache_enable();
 }

-- 
2.53.0