intel car: Use MTRR WRPROT type for XIP cache
XIP cachelines contain the executable to run, we never want
that to get modified. With the change such erronous writes
are ignored and next cacheline miss will fetch from boot
media (SPI / FWH flash).
Change-Id: I52b62866b5658e103281ffa1a91e1c64262f3175
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/15778
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
diff --git a/src/cpu/intel/car/cache_as_ram_ht.inc b/src/cpu/intel/car/cache_as_ram_ht.inc
index f9a2b36..0ec2a9d 100644
--- a/src/cpu/intel/car/cache_as_ram_ht.inc
+++ b/src/cpu/intel/car/cache_as_ram_ht.inc
@@ -310,7 +310,7 @@
*/
movl $copy_and_run, %eax
andl $(~(CONFIG_XIP_ROM_SIZE - 1)), %eax
- orl $MTRR_TYPE_WRBACK, %eax
+ orl $MTRR_TYPE_WRPROT, %eax
wrmsr
movl $MTRR_PHYS_MASK(1), %ecx