tcg: signal-free qemu_cpu_kick

Signals are slow and do not exist on Win32.  The previous patches
have done most of the legwork to introduce memory barriers (some
of them were even there already for the sake of Windows!) and
we can now set the flags directly in the iothread.

qemu_cpu_kick_thread is not used anymore on TCG, since the TCG thread is
never outside usermode while the CPU is running (not halted).  Instead run
the content of the signal handler (now in qemu_cpu_kick_no_halt) directly.
qemu_cpu_kick_no_halt is also used in qemu_mutex_lock_iothread to avoid
the overhead of qemu_cond_broadcast.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 8612655..2b4936a 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -268,7 +268,7 @@ struct CPUState {
     bool created;
     bool stop;
     bool stopped;
-    volatile sig_atomic_t exit_request;
+    bool exit_request;
     uint32_t interrupt_request;
     int singlestep_enabled;
     int64_t icount_extra;
@@ -319,7 +319,7 @@ struct CPUState {
        offset from AREG0.  Leave this field at the end so as to make the
        (absolute value) offset as small as possible.  This reduces code
        size, especially for hosts without large memory offsets.  */
-    volatile sig_atomic_t tcg_exit_req;
+    uint32_t tcg_exit_req;
 };
 
 QTAILQ_HEAD(CPUTailQ, CPUState);