Revert "accel/tcg: Init TCG cflags in vCPU thread handler"

Commit a82fd5a4ec24d was intended to be a code cleanup, but
unfortunately it has a bug. It moves the initialization of the
TCG cflags from the "start a new vcpu" function to the
thread handler; this is fine when each vcpu has its own thread,
but when we are doing round-robin of vcpus on a single thread
we end up only initializing the cflags for CPU 0, not for any
of the others.

The most obvious effect of this bug is that running in icount
mode with more than one CPU is broken; typically the guest
hangs shortly after it brings up the secondary CPUs.

This reverts commit a82fd5a4ec24d923ff1e6da128c0fd4a74079d99.

Cc: qemu-stable@nongnu.org
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20221021163409.3674911-1-peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

diff --git a/accel/tcg/tcg-accel-ops-mttcg.c b/accel/tcg/tcg-accel-ops-mttcg.c
index ba997f6cfe42c81faea6b2e2d4104cbcb9a69b72..d50239e0e28f4925c5d22d7c857210723d4296bd 100644 (file)
--- a/accel/tcg/tcg-accel-ops-mttcg.c
+++ b/accel/tcg/tcg-accel-ops-mttcg.c
@@ -70,8 +70,6 @@ static void *mttcg_cpu_thread_fn(void *arg)
     assert(tcg_enabled());
     g_assert(!icount_enabled());
 
-    tcg_cpu_init_cflags(cpu, current_machine->smp.max_cpus > 1);
-
     rcu_register_thread();
     force_rcu.notifier.notify = mttcg_force_rcu;
     force_rcu.cpu = cpu;
@@ -141,6 +139,9 @@ void mttcg_start_vcpu_thread(CPUState *cpu)
 {
     char thread_name[VCPU_THREAD_NAME_SIZE];
 
+    g_assert(tcg_enabled());
+    tcg_cpu_init_cflags(cpu, current_machine->smp.max_cpus > 1);
+
     cpu->thread = g_new0(QemuThread, 1);
     cpu->halt_cond = g_malloc0(sizeof(QemuCond));
     qemu_cond_init(cpu->halt_cond);

diff --git a/accel/tcg/tcg-accel-ops-rr.c b/accel/tcg/tcg-accel-ops-rr.c
index cc8adc23802c7b62f13a1c6d2573e56950a9e537..1a72149f0e46c55b3ab80f2874619d0b1f245b10 100644 (file)
--- a/accel/tcg/tcg-accel-ops-rr.c
+++ b/accel/tcg/tcg-accel-ops-rr.c
@@ -152,9 +152,7 @@ static void *rr_cpu_thread_fn(void *arg)
     Notifier force_rcu;
     CPUState *cpu = arg;
 
-    g_assert(tcg_enabled());
-    tcg_cpu_init_cflags(cpu, false);
-
+    assert(tcg_enabled());
     rcu_register_thread();
     force_rcu.notify = rr_force_rcu;
     rcu_add_force_rcu_notifier(&force_rcu);
@@ -277,6 +275,9 @@ void rr_start_vcpu_thread(CPUState *cpu)
     static QemuCond *single_tcg_halt_cond;
     static QemuThread *single_tcg_cpu_thread;
 
+    g_assert(tcg_enabled());
+    tcg_cpu_init_cflags(cpu, false);
+
     if (!single_tcg_cpu_thread) {
         cpu->thread = g_new0(QemuThread, 1);
         cpu->halt_cond = g_new0(QemuCond, 1);