target-arm: add emulation of PSCI calls for system emulation

Add support for handling PSCI calls in system emulation. Both version
0.1 and 0.2 of the PSCI spec are supported. Platforms can enable support
by setting the "psci-conduit" QOM property on the cpus to SMC or HVC
emulation and having a PSCI binding in their dtb.

Signed-off-by: Rob Herring <rob.herring@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1412865028-17725-7-git-send-email-peter.maydell@linaro.org
[PMM: made system reset/off PSCI functions power down the CPU so
 we obey the PSCI API requirement never to return from them;
 rearranged how the code is plumbed into the exception system,
 so that we split "is this a valid call?" from "do the call"]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index 5652096dce..464a5ce567 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -387,11 +387,19 @@ void HELPER(clear_pstate_ss)(CPUARMState *env)
 
 void HELPER(pre_hvc)(CPUARMState *env)
 {
+    ARMCPU *cpu = arm_env_get_cpu(env);
     int cur_el = arm_current_pl(env);
     /* FIXME: Use actual secure state.  */
     bool secure = false;
     bool undef;
 
+    if (arm_is_psci_call(cpu, EXCP_HVC)) {
+        /* If PSCI is enabled and this looks like a valid PSCI call then
+         * that overrides the architecturally mandated HVC behaviour.
+         */
+        return;
+    }
+
     if (!arm_feature(env, ARM_FEATURE_EL2)) {
         /* If EL2 doesn't exist, HVC always UNDEFs */
         undef = true;
@@ -419,6 +427,7 @@ void HELPER(pre_hvc)(CPUARMState *env)
 
 void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome)
 {
+    ARMCPU *cpu = arm_env_get_cpu(env);
     int cur_el = arm_current_pl(env);
     /* FIXME: Use real secure state.  */
     bool secure = false;
@@ -430,6 +439,13 @@ void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome)
      */
     bool undef = is_a64(env) ? smd : (!secure && smd);
 
+    if (arm_is_psci_call(cpu, EXCP_SMC)) {
+        /* If PSCI is enabled and this looks like a valid PSCI call then
+         * that overrides the architecturally mandated SMC behaviour.
+         */
+        return;
+    }
+
     if (!arm_feature(env, ARM_FEATURE_EL3)) {
         /* If we have no EL3 then SMC always UNDEFs */
         undef = true;