monitor: Add drift info to 'info jit'

Show in 'info jit' the current delay between the host clock
and the guest clock. In addition, print the maximum advance
and delay of the guest compared to the host.

Signed-off-by: Sebastian Tanase <sebastian.tanase@openwide.fr>
Tested-by: Camille Bégué <camille.begue@openwide.fr>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

cpu-exec.c

@@ -105,6 +105,12 @@ static void init_delay_params(SyncClocks *sc,
                    sc->realtime_clock +
                    cpu_get_clock_offset();
     sc->last_cpu_icount = cpu->icount_extra + cpu->icount_decr.u16.low;
+    if (sc->diff_clk < max_delay) {
+        max_delay = sc->diff_clk;
+    }
+    if (sc->diff_clk > max_advance) {
+        max_advance = sc->diff_clk;
+    }
 
     /* Print every 2s max if the guest is late. We limit the number
        of printed messages to NB_PRINT_MAX(currently 100) */

cpus.c

@@ -64,6 +64,8 @@
 #endif /* CONFIG_LINUX */
 
 static CPUState *next_cpu;
+int64_t max_delay;
+int64_t max_advance;
 
 bool cpu_is_stopped(CPUState *cpu)
 {
@@ -1552,3 +1554,20 @@ void qmp_inject_nmi(Error **errp)
     error_set(errp, QERR_UNSUPPORTED);
 #endif
 }
+
+void dump_drift_info(FILE *f, fprintf_function cpu_fprintf)
+{
+    if (!use_icount) {
+        return;
+    }
+
+    cpu_fprintf(f, "Host - Guest clock  %"PRIi64" ms\n",
+                (cpu_get_clock() - cpu_get_icount())/SCALE_MS);
+    if (icount_align_option) {
+        cpu_fprintf(f, "Max guest delay     %"PRIi64" ms\n", -max_delay/SCALE_MS);
+        cpu_fprintf(f, "Max guest advance   %"PRIi64" ms\n", max_advance/SCALE_MS);
+    } else {
+        cpu_fprintf(f, "Max guest delay     NA\n");
+        cpu_fprintf(f, "Max guest advance   NA\n");
+    }
+}

include/qemu-common.h

@@ -109,6 +109,10 @@ static inline char *realpath(const char *path, char *resolved_path)
 void configure_icount(QemuOpts *opts, Error **errp);
 extern int use_icount;
 extern int icount_align_option;
+/* drift information for info jit command */
+extern int64_t max_delay;
+extern int64_t max_advance;
+void dump_drift_info(FILE *f, fprintf_function cpu_fprintf);
 
 #include "qemu/osdep.h"
 #include "qemu/bswap.h"

monitor.c

@@ -1047,6 +1047,7 @@ static void do_info_registers(Monitor *mon, const QDict *qdict)
 static void do_info_jit(Monitor *mon, const QDict *qdict)
 {
     dump_exec_info((FILE *)mon, monitor_fprintf);
+    dump_drift_info((FILE *)mon, monitor_fprintf);
 }
 
 static void do_info_history(Monitor *mon, const QDict *qdict)