hv: debug: Add hv console callback to VM-exit event

In some scenarios (e.g., nested) where lapic-pt is enabled for a vcpu
running on a pcpu hosting console timer, the hv console will be
inaccessible.

This patch adds the console callback to every VM-exit event so that the
console can still be somewhat functional under such circumstance.

Since this is VM-exit driven, the VM-exit/second can be low in certain
cases (e.g., idle or running stress workload). In extreme cases where
the guest panics/hangs, there will be no VM-exits at all.

In most cases, the shell is laggy but functional (probably enough for
debugging purpose).

Tracked-On: #6312
Signed-off-by: Yifan Liu <yifan1.liu@intel.com>

hypervisor/include/debug/console.h

@@ -8,6 +8,7 @@
 #define CONSOLE_H
 
 #include <vuart.h>
+#include <asm/guest/vcpu.h>
 
 /** Initializes the console module.
  *
@@ -35,6 +36,7 @@ void console_putc(const char *ch);
 char console_getc(void);
 
 void console_setup_timer(void);
+void console_vmexit_callback(struct acrn_vcpu *vcpu);
 
 void suspend_console(void);
 void resume_console(void);