[Qemu-devel] [PATCH V2 3/4] target-arm: Change reset to highest available EL

[Greg Bellows <greg.bellows@linaro.org>]

Update to arm_cpu_reset() to reset into the highest available exception level
based on the set ARM features.

Signed-off-by: Greg Bellows <greg.bellows@linaro.org>

---

v1 -> v2
- Added Linux boot into secure EL1
- Added reset to EL2 if enabled
- Removed extraneous SCR.NS reset
- Fixed incorrect feature check
---
 hw/arm/boot.c    | 22 ++++++++++++++++++++--
 target-arm/cpu.c |  9 ++++++++-
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index 52ebd8b..a48d1b2 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -463,8 +463,26 @@ static void do_cpu_reset(void *opaque)
              * (SCR.NS = 0), we change that here if non-secure boot has been
              * requested.
              */
-            if (arm_feature(env, ARM_FEATURE_EL3) && !info->secure_boot) {
-                env->cp15.scr_el3 |= SCR_NS;
+            if (arm_feature(env, ARM_FEATURE_EL3)) {
+                /* AArch64 is defined to come out of reset into EL3 if enabled.
+                 * If we are booting Linux then we need to adjust our EL as
+                 * Linux expects us to be in EL2 or EL1.  AArch32 resets into
+                 * SVC, which Linux expects, so no privilege/exception level to
+                 * adjust.
+                 */
+                if (env->aarch64) {
+                    if (arm_feature(env, ARM_FEATURE_EL2)) {
+                        env->pstate = PSTATE_MODE_EL2h;
+                    } else {
+                        env->pstate = PSTATE_MODE_EL1h;
+                    }
+                }
+
+                /* Set to non-secure if not a secure boot */
+                if (!info->secure_boot) {
+                    /* Linux expects non-secure state */
+                    env->cp15.scr_el3 |= SCR_NS;
+                }
             }
 
             if (CPU(cpu) == first_cpu) {
diff --git a/target-arm/cpu.c b/target-arm/cpu.c
index 285947f..f43e2de 100644
--- a/target-arm/cpu.c
+++ b/target-arm/cpu.c
@@ -113,7 +113,14 @@ static void arm_cpu_reset(CPUState *s)
         /* and to the FP/Neon instructions */
         env->cp15.c1_coproc = deposit64(env->cp15.c1_coproc, 20, 2, 3);
 #else
-        env->pstate = PSTATE_MODE_EL1h;
+        /* Reset into the highest available EL */
+        if (arm_feature(env, ARM_FEATURE_EL3)) {
+            env->pstate = PSTATE_MODE_EL3h;
+        } else if (arm_feature(env, ARM_FEATURE_EL2)) {
+            env->pstate = PSTATE_MODE_EL2h;
+        } else {
+            env->pstate = PSTATE_MODE_EL1h;
+        }
         env->pc = cpu->rvbar;
 #endif
     } else {
-- 
1.8.3.2