[Qemu-devel] [PULL 37/37] target-arm: fix TTBCR write masking

[Peter Maydell]

From: Sergey Fedorov <address@hidden>

Current implementation is not accurate according to ARMv7-AR reference
manual. See "B4.1.153 TTBCR, Translation Table Base Control Register,
VMSA | TTBCR format when using the Long-descriptor translation table
format". When LPAE feature is supported, EAE, bit[31] selects
translation descriptor format and, therefore, TTBCR format.

Signed-off-by: Sergey Fedorov <address@hidden>
Reviewed-by: Peter Maydell <address@hidden>
Message-id: address@hidden
Signed-off-by: Peter Maydell <address@hidden>
---
 target-arm/helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target-arm/helper.c b/target-arm/helper.c
index 8ec4cb1..5e5e5aa 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -1173,7 +1173,7 @@ static int vmsa_ttbcr_raw_write(CPUARMState *env, const 
ARMCPRegInfo *ri,
 {
     int maskshift = extract32(value, 0, 3);
 
-    if (arm_feature(env, ARM_FEATURE_LPAE)) {
+    if (arm_feature(env, ARM_FEATURE_LPAE) && (value & (1 << 31))) {
         value &= ~((7 << 19) | (3 << 14) | (0xf << 3));
     } else {
         value &= 7;
-- 
1.8.5