target/arm/hvf/hvf: Document $pc adjustment in HVF & SMC

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
index f31b6e54ee7d43777e25e7bc2c5683abf7036ec9..805fe75e6b1a52e49716c4b84252cb83ae7541b6 100644 (file)
--- a/target/arm/hvf/hvf.c
+++ b/target/arm/hvf/hvf.c
@@ -1936,6 +1936,7 @@ static int hvf_handle_exception(CPUState *cpu, hv_vcpu_exit_exception_t *excp)
     case EC_AA64_HVC:
         cpu_synchronize_state(cpu);
         if (arm_is_psci_call(arm_cpu, EXCP_HVC)) {
+            /* Do NOT advance $pc for HVC */
             if (!hvf_handle_psci_call(cpu)) {
                 trace_hvf_unknown_hvc(env->pc, env->xregs[0]);
                 /* SMCCC 1.3 section 5.2 says every unknown SMCCC call returns -1 */
@@ -1949,6 +1950,7 @@ static int hvf_handle_exception(CPUState *cpu, hv_vcpu_exit_exception_t *excp)
     case EC_AA64_SMC:
         cpu_synchronize_state(cpu);
         if (arm_is_psci_call(arm_cpu, EXCP_SMC)) {
+            /* Secure Monitor Call exception, we need to advance $pc */
             advance_pc = true;
 
             if (!hvf_handle_psci_call(cpu)) {