accel/tcg: Use one_insn_per_tb global instead of old singlestep global

The only place left that looks at the old 'singlestep' global
variable is the TCG curr_cflags() function.  Replace the old global
with a new 'one_insn_per_tb' which is defined in tcg-all.c and
declared in accel/tcg/internal.h.  This keeps it restricted to the
TCG code, unlike 'singlestep' which was available to every file in
the system and defined in multiple different places for softmmu vs
linux-user vs bsd-user.

While we're making this change, use qatomic_read() and qatomic_set()
on the accesses to the new global, because TCG will read it without
holding a lock.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20230417164041.684562-4-peter.maydell@linaro.org

1 files changed, 4 insertions, 2 deletions

diff --git a/accel/tcg/tcg-all.c b/accel/tcg/tcg-all.c
index fcf361c8db..a831f8d7c3 100644
--- a/accel/tcg/tcg-all.c
+++ b/accel/tcg/tcg-all.c
@@ -31,6 +31,7 @@
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "qemu/accel.h"
+#include "qemu/atomic.h"
 #include "qapi/qapi-builtin-visit.h"
 #include "qemu/units.h"
 #if !defined(CONFIG_USER_ONLY)
@@ -110,6 +111,7 @@ static void tcg_accel_instance_init(Object *obj)
 }
 
 bool mttcg_enabled;
+bool one_insn_per_tb;
 
 static int tcg_init_machine(MachineState *ms)
 {
@@ -219,8 +221,8 @@ static void tcg_set_one_insn_per_tb(Object *obj, bool value, Error **errp)
 {
     TCGState *s = TCG_STATE(obj);
     s->one_insn_per_tb = value;
-    /* For the moment, set the global also: this changes the behaviour */
-    singlestep = value;
+    /* Set the global also: this changes the behaviour */
+    qatomic_set(&one_insn_per_tb, value);
 }
 
 static int tcg_gdbstub_supported_sstep_flags(void)