qtest: split configuration of qtest accelerator and chardev

qtest uses the icount infrastructure to implement a test-driven vm_clock.  This
however is not necessary when using -qtest as a "probe" together with a normal
TCG-, KVM- or Xen-based virtual machine.  Hence, split out the call to
configure_icount into a new function that is called only for "-machine
accel=qtest"; and disable those commands when running with an accelerator
other than qtest.

This also fixes an assertion failure with "qemu-system-x86_64 -machine
accel=qtest" but no -qtest option.  This is a valid case, albeit somewhat
weird; nothing will happen in the VM but you'll still be able to
interact with the monitor or the GUI.

Now that qtest_init is not limited to an int(void) function, change
global variables that are not used outside qtest_init to arguments.

And finally, cleanup useless parts of include/sysemu/qtest.h.  The file
is not used at all for user-only emulation, and qtest is not available
on Win32 due to its usage of sigwait.

Reported-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

include/sysemu/qtest.h

@@ -16,38 +16,23 @@
 
 #include "qemu-common.h"
 
-#if !defined(CONFIG_USER_ONLY)
 extern bool qtest_allowed;
-extern const char *qtest_chrdev;
-extern const char *qtest_log;
 
 static inline bool qtest_enabled(void)
 {
     return qtest_allowed;
 }
 
+int qtest_init_accel(void);
+void qtest_init(const char *qtest_chrdev, const char *qtest_log);
+
 static inline int qtest_available(void)
 {
+#ifdef CONFIG_POSIX
     return 1;
-}
-
-int qtest_init(void);
 #else
-static inline bool qtest_enabled(void)
-{
-    return false;
-}
-
-static inline int qtest_available(void)
-{
-    return 0;
-}
-
-static inline int qtest_init(void)
-{
     return 0;
+#endif
 }
 
 #endif
-
-#endif

qtest.c

@@ -22,8 +22,6 @@
 
 #define MAX_IRQ 256
 
-const char *qtest_chrdev;
-const char *qtest_log;
 bool qtest_allowed;
 
 static DeviceState *irq_intercept_dev;
@@ -406,7 +404,7 @@ static void qtest_process_command(CharDriverState *chr, gchar **words)
 
         qtest_send_prefix(chr);
         qtest_send(chr, "OK\n");
-    } else if (strcmp(words[0], "clock_step") == 0) {
+    } else if (qtest_enabled() && strcmp(words[0], "clock_step") == 0) {
         int64_t ns;
 
         if (words[1]) {
@@ -417,7 +415,7 @@ static void qtest_process_command(CharDriverState *chr, gchar **words)
         qtest_clock_warp(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + ns);
         qtest_send_prefix(chr);
         qtest_send(chr, "OK %"PRIi64"\n", (int64_t)qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
-    } else if (strcmp(words[0], "clock_set") == 0) {
+    } else if (qtest_enabled() && strcmp(words[0], "clock_set") == 0) {
         int64_t ns;
 
         g_assert(words[1]);
@@ -502,13 +500,17 @@ static void qtest_event(void *opaque, int event)
     }
 }
 
-int qtest_init(void)
+int qtest_init_accel(void)
+{
+    configure_icount("0");
+
+    return 0;
+}
+
+void qtest_init(const char *qtest_chrdev, const char *qtest_log)
 {
     CharDriverState *chr;
 
-    g_assert(qtest_chrdev != NULL);
-
-    configure_icount("0");
     chr = qemu_chr_new("qtest", qtest_chrdev, NULL);
 
     qemu_chr_add_handlers(chr, qtest_can_read, qtest_read, qtest_event, chr);
@@ -525,6 +527,4 @@ int qtest_init(void)
     }
 
     qtest_chr = chr;
-
-    return 0;
 }

vl.c

@@ -2624,7 +2624,7 @@ static struct {
     { "tcg", "tcg", tcg_available, tcg_init, &tcg_allowed },
     { "xen", "Xen", xen_available, xen_init, &xen_allowed },
     { "kvm", "KVM", kvm_available, kvm_init, &kvm_allowed },
-    { "qtest", "QTest", qtest_available, qtest_init, &qtest_allowed },
+    { "qtest", "QTest", qtest_available, qtest_init_accel, &qtest_allowed },
 };
 
 static int configure_accelerator(void)
@@ -2836,6 +2836,8 @@ int main(int argc, char **argv, char **envp)
     QEMUMachine *machine;
     const char *cpu_model;
     const char *vga_model = "none";
+    const char *qtest_chrdev = NULL;
+    const char *qtest_log = NULL;
     const char *pid_file = NULL;
     const char *incoming = NULL;
 #ifdef CONFIG_VNC
@@ -4043,8 +4045,8 @@ int main(int argc, char **argv, char **envp)
 
     configure_accelerator();
 
-    if (!qtest_enabled() && qtest_chrdev) {
+    if (qtest_chrdev) {
-        qtest_init();
+        qtest_init(qtest_chrdev, qtest_log);
     }
 
     machine_opts = qemu_get_machine_opts();