whpx: Added support for breakpoints and stepping

Below is the updated version of the patch adding debugging support to WHPX.
It incorporates feedback from Alex Bennée and Peter Maydell regarding not
changing the emulation logic depending on the gdb connection status.

Instead of checking for an active gdb connection to determine whether QEMU
should intercept the INT1 exceptions, it now checks whether any breakpoints
have been set, or whether gdb has explicitly requested one or more CPUs to
do single-stepping. Having none of these condition present now has the same
effect as not using gdb at all.

Message-Id: <0e7f01d82e9e$00e9c360$02bd4a20$@sysprogs.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index 668bef9..23b3048 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -672,7 +672,7 @@ int vm_stop(RunState state)
  * Returns -1 if the vCPUs are not to be restarted (e.g. if they are already
  * running or in case of an error condition), 0 otherwise.
  */
-int vm_prepare_start(void)
+int vm_prepare_start(bool step_pending)
 {
     RunState requested;
 
@@ -692,6 +692,14 @@ int vm_prepare_start(void)
         return -1;
     }
 
+    /*
+     * WHPX accelerator needs to know whether we are going to step
+     * any CPUs, before starting the first one.
+     */
+    if (cpus_accel->synchronize_pre_resume) {
+        cpus_accel->synchronize_pre_resume(step_pending);
+    }
+
     /* We are sending this now, but the CPUs will be resumed shortly later */
     qapi_event_send_resume();
 
@@ -703,7 +711,7 @@ int vm_prepare_start(void)
 
 void vm_start(void)
 {
-    if (!vm_prepare_start()) {
+    if (!vm_prepare_start(false)) {
         resume_all_vcpus();
     }
 }