This adds support for single-step. There isn't much to do on the QEMU
side as after we set-up the request for single step via the debug ioctl
it is all handled within the kernel.

Signed-off-by: Alex Benn?e <redacted>

---
v2
  - convert to using HSR_EC
v3
  - use internals.h definitions
---
 target-arm/kvm.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/target-arm/kvm.c b/target-arm/kvm.c
index 50f70ef..d505a7e 100644
--- a/target-arm/kvm.c
+++ b/target-arm/kvm.c

@@ -535,6 +535,13 @@ static int kvm_handle_debug(CPUState *cs, struct kvm_run *run)
     kvm_cpu_synchronize_state(cs);

     switch (hsr_ec) {
+    case EC_SOFTWARESTEP:
+        if (cs->singlestep_enabled) {
+            return true;
+        } else {
+            error_report("Came out of SINGLE STEP when not enabled");
+        }
+        break;
     case EC_AA64_BKPT:
         if (kvm_find_sw_breakpoint(cs, env->pc)) {
             return true;

@@ -595,6 +602,9 @@ int kvm_arch_on_sigbus(int code, void *addr)

 void kvm_arch_update_guest_debug(CPUState *cs, struct kvm_guest_debug *dbg)
 {
+    if (cs->singlestep_enabled) {
+        dbg->control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP;
+    }