kvm: Fix guest single-stepping

Hopefully the last regression of 4c0960c0: KVM_SET_GUEST_DEBUG requires
properly synchronized guest registers (on x86: eflags) on entry.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/kvm-all.c b/kvm-all.c
index 7dcc55319c..f50c31c643 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -938,7 +938,13 @@ struct kvm_set_guest_debug_data {
 static void kvm_invoke_set_guest_debug(void *data)
 {
     struct kvm_set_guest_debug_data *dbg_data = data;
-    dbg_data->err = kvm_vcpu_ioctl(dbg_data->env, KVM_SET_GUEST_DEBUG, &dbg_data->dbg);
+    CPUState *env = dbg_data->env;
+
+    if (env->kvm_state->regs_modified) {
+        kvm_arch_put_registers(env);
+        env->kvm_state->regs_modified = 0;
+    }
+    dbg_data->err = kvm_vcpu_ioctl(env, KVM_SET_GUEST_DEBUG, &dbg_data->dbg);
 }
 
 int kvm_update_guest_debug(CPUState *env, unsigned long reinject_trap)