gdbstub, kvm: let KVM report supported singlestep flags

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
[Extracted from Maxim's patch into a separate commit. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20211111110604.207376-5-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/gdbstub.c b/gdbstub.c
index a955175fd4..3c14c6a038 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -391,6 +391,8 @@ static void init_gdbserver_state(void)
      */
     if (replay_mode != REPLAY_MODE_NONE) {
         gdbserver_state.supported_sstep_flags = SSTEP_ENABLE;
+    } else if (kvm_enabled()) {
+        gdbserver_state.supported_sstep_flags = kvm_get_supported_sstep_flags();
     } else {
         gdbserver_state.supported_sstep_flags =
             SSTEP_ENABLE | SSTEP_NOIRQ | SSTEP_NOTIMER;
@@ -400,7 +402,8 @@ static void init_gdbserver_state(void)
      * By default use no IRQs and no timers while single stepping so as to
      * make single stepping like an ICE HW step.
      */
-    gdbserver_state.sstep_flags = gdbserver_state.supported_sstep_flags;
+    gdbserver_state.sstep_flags = SSTEP_ENABLE | SSTEP_NOIRQ | SSTEP_NOTIMER;
+    gdbserver_state.sstep_flags &= gdbserver_state.supported_sstep_flags;
 
 }
 
@@ -3520,6 +3523,11 @@ int gdbserver_start(const char *device)
         return -1;
     }
 
+    if (kvm_enabled() && !kvm_supports_guest_debug()) {
+        error_report("gdbstub: KVM doesn't support guest debugging");
+        return -1;
+    }
+
     if (!device)
         return -1;
     if (strcmp(device, "none") != 0) {