icount: add sleep parameter to the icount option to set icount_sleep mode

The 'sleep' parameter sets the icount_sleep mode, which is enabled by
default. To disable it, add the 'sleep=no' parameter (or 'nosleep') to the
qemu -icount option.

Signed-off-by: Victor CLEMENT <victor.clement@openwide.fr>
Message-Id: <1432912446-9811-3-git-send-email-victor.clement@openwide.fr>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 22 insertions, 2 deletions

diff --git a/cpus.c b/cpus.c
index 688eb73ec2..4e90e63b43 100644
--- a/cpus.c
+++ b/cpus.c
@@ -520,11 +520,18 @@ void configure_icount(QemuOpts *opts, Error **errp)
         }
         return;
     }
+
+    icount_sleep = qemu_opt_get_bool(opts, "sleep", true);
     if (icount_sleep) {
         icount_warp_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT,
                                          icount_warp_rt, NULL);
     }
+
     icount_align_option = qemu_opt_get_bool(opts, "align", false);
+
+    if (icount_align_option && !icount_sleep) {
+        error_setg(errp, "align=on and sleep=no are incompatible");
+    }
     if (strcmp(option, "auto") != 0) {
         errno = 0;
         icount_time_shift = strtol(option, &rem_str, 0);
@@ -535,6 +542,8 @@ void configure_icount(QemuOpts *opts, Error **errp)
         return;
     } else if (icount_align_option) {
         error_setg(errp, "shift=auto and align=on are incompatible");
+    } else if (!icount_sleep) {
+        error_setg(errp, "shift=auto and sleep=no are incompatible");
     }
 
     use_icount = 2;
diff --git a/qemu-options.hx b/qemu-options.hx
index b3db6cbe86..85883f165a 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3100,9 +3100,10 @@ re-inject them.
 ETEXI
 
 DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
-    "-icount [shift=N|auto][,align=on|off]\n" \
+    "-icount [shift=N|auto][,align=on|off][,sleep=no]\n" \
     "                enable virtual instruction counter with 2^N clock ticks per\n" \
-    "                instruction and enable aligning the host and virtual clocks\n", QEMU_ARCH_ALL)
+    "                instruction, enable aligning the host and virtual clocks\n" \
+    "                or disable real time cpu sleeping\n", QEMU_ARCH_ALL)
 STEXI
 @item -icount [shift=@var{N}|auto]
 @findex -icount
@@ -3111,6 +3112,13 @@ instruction every 2^@var{N} ns of virtual time.  If @code{auto} is specified
 then the virtual cpu speed will be automatically adjusted to keep virtual
 time within a few seconds of real time.
 
+When the virtual cpu is sleeping, the virtual time will advance at default
+speed unless @option{sleep=no} is specified.
+With @option{sleep=no}, the virtual time will jump to the next timer deadline
+instantly whenever the virtual cpu goes to sleep mode and will not advance
+if no timer is enabled. This behavior give deterministic execution times from
+the guest point of view.
+
 Note that while this option can give deterministic behavior, it does not
 provide cycle accurate emulation.  Modern CPUs contain superscalar out of
 order cores with complex cache hierarchies.  The number of instructions
diff --git a/vl.c b/vl.c
index cdd81b4486..df5a7273c9 100644
--- a/vl.c
+++ b/vl.c
@@ -468,6 +468,9 @@ static QemuOptsList qemu_icount_opts = {
         }, {
             .name = "align",
             .type = QEMU_OPT_BOOL,
+        }, {
+            .name = "sleep",
+            .type = QEMU_OPT_BOOL,
         },
         { /* end of list */ }
     },