qemu_cpu_kick() does not always have to set cpu->exit_request,
though it does for now. Introduce a function tcg_kick_vcpu_thread()
which can be changed in the future to not set cpu->exit_request,
and reserve cpu_exit() for when *all accelerators* need to set
that flag.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
docs/devel/tcg-icount.rst | 2 +-
accel/tcg/tcg-accel-ops-mttcg.h | 3 ---
include/exec/cpu-common.h | 1 +
accel/tcg/cpu-exec.c | 17 ++++++++++++++++-
accel/tcg/tcg-accel-ops-mttcg.c | 5 -----
accel/tcg/tcg-accel-ops-rr.c | 2 +-
accel/tcg/tcg-accel-ops.c | 2 +-
bsd-user/main.c | 2 +-
linux-user/main.c | 2 +-
9 files changed, 22 insertions(+), 14 deletions(-)
diff --git a/docs/devel/tcg-icount.rst b/docs/devel/tcg-icount.rst
index 7df883446a7..a1dcd79e0fd 100644
--- a/docs/devel/tcg-icount.rst
+++ b/docs/devel/tcg-icount.rst
@@ -37,7 +37,7 @@ translator starts by allocating a budget of instructions to be
executed. The budget of instructions is limited by how long it will be
until the next timer will expire. We store this budget as part of a
vCPU icount_decr field which shared with the machinery for handling
-cpu_exit(). The whole field is checked at the start of every
+qemu_cpu_kick(). The whole field is checked at the start of every
translated block and will cause a return to the outer loop to deal
with whatever caused the exit.
diff --git a/accel/tcg/tcg-accel-ops-mttcg.h b/accel/tcg/tcg-accel-ops-mttcg.h
index 8ffa7a9a9fe..5c145cc8595 100644
--- a/accel/tcg/tcg-accel-ops-mttcg.h
+++ b/accel/tcg/tcg-accel-ops-mttcg.h
@@ -10,9 +10,6 @@
#ifndef TCG_ACCEL_OPS_MTTCG_H
#define TCG_ACCEL_OPS_MTTCG_H
-/* kick MTTCG vCPU thread */
-void mttcg_kick_vcpu_thread(CPUState *cpu);
-
/* start an mttcg vCPU thread */
void mttcg_start_vcpu_thread(CPUState *cpu);
diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 9b658a3f48f..e843b09cc99 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -226,6 +226,7 @@ G_NORETURN void cpu_loop_exit(CPUState *cpu);
G_NORETURN void cpu_loop_exit_restore(CPUState *cpu, uintptr_t pc);
/* accel/tcg/cpu-exec.c */
+void tcg_kick_vcpu_thread(CPUState *cpu);
int cpu_exec(CPUState *cpu);
/**
diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index 4bd9ee01c19..1a973596d87 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -748,6 +748,20 @@ static inline bool cpu_handle_exception(CPUState *cpu, int
*ret)
return false;
}
+void tcg_kick_vcpu_thread(CPUState *cpu)
+{
+ /*
+ * Ensure cpu_exec will see the reason why the exit request was set.
+ * FIXME: this is not always needed. Other accelerators instead
+ * read interrupt_request and set exit_request on demand from the
+ * CPU thread; see kvm_arch_pre_run() for example.
+ */
+ qatomic_store_release(&cpu->exit_request, 1);
+
+ /* Ensure cpu_exec will see the exit request after TCG has exited. */
+ qatomic_store_release(&cpu->neg.icount_decr.u16.high, -1);
+}
+
static inline bool icount_exit_request(CPUState *cpu)
{
if (!icount_enabled()) {
@@ -774,7 +788,8 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
/* Clear the interrupt flag now since we're processing
* cpu->interrupt_request and cpu->exit_request.
* Ensure zeroing happens before reading cpu->exit_request or
- * cpu->interrupt_request (see also smp_wmb in cpu_exit())
+ * cpu->interrupt_request (see also store-release in
+ * tcg_kick_vcpu_thread())
*/
qatomic_set_mb(&cpu->neg.icount_decr.u16.high, 0);
diff --git a/accel/tcg/tcg-accel-ops-mttcg.c b/accel/tcg/tcg-accel-ops-mttcg.c
index 39237421757..5757324a8c2 100644
--- a/accel/tcg/tcg-accel-ops-mttcg.c
+++ b/accel/tcg/tcg-accel-ops-mttcg.c
@@ -123,11 +123,6 @@ static void *mttcg_cpu_thread_fn(void *arg)
return NULL;
}
-void mttcg_kick_vcpu_thread(CPUState *cpu)
-{
- cpu_exit(cpu);
-}
-
void mttcg_start_vcpu_thread(CPUState *cpu)
{
char thread_name[VCPU_THREAD_NAME_SIZE];
diff --git a/accel/tcg/tcg-accel-ops-rr.c b/accel/tcg/tcg-accel-ops-rr.c
index c06f3beef2e..87b49377c78 100644
--- a/accel/tcg/tcg-accel-ops-rr.c
+++ b/accel/tcg/tcg-accel-ops-rr.c
@@ -43,7 +43,7 @@ void rr_kick_vcpu_thread(CPUState *unused)
CPUState *cpu;
CPU_FOREACH(cpu) {
- cpu_exit(cpu);
+ tcg_kick_vcpu_thread(cpu);
};
}
diff --git a/accel/tcg/tcg-accel-ops.c b/accel/tcg/tcg-accel-ops.c
index 02c7600bb7d..f4d5372866a 100644
--- a/accel/tcg/tcg-accel-ops.c
+++ b/accel/tcg/tcg-accel-ops.c
@@ -207,7 +207,7 @@ static void tcg_accel_ops_init(AccelClass *ac)
if (qemu_tcg_mttcg_enabled()) {
ops->create_vcpu_thread = mttcg_start_vcpu_thread;
- ops->kick_vcpu_thread = mttcg_kick_vcpu_thread;
+ ops->kick_vcpu_thread = tcg_kick_vcpu_thread;
ops->handle_interrupt = tcg_handle_interrupt;
} else {
ops->create_vcpu_thread = rr_start_vcpu_thread;
diff --git a/bsd-user/main.c b/bsd-user/main.c
index 7e5d4bbce09..20159207040 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -216,7 +216,7 @@ bool qemu_cpu_is_self(CPUState *cpu)
void qemu_cpu_kick(CPUState *cpu)
{
- cpu_exit(cpu);
+ tcg_kick_vcpu_thread(cpu);
}
/* Assumes contents are already zeroed. */
diff --git a/linux-user/main.c b/linux-user/main.c
index 68972f00a15..dc68fd448b7 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -192,7 +192,7 @@ bool qemu_cpu_is_self(CPUState *cpu)
void qemu_cpu_kick(CPUState *cpu)
{
- cpu_exit(cpu);
+ tcg_kick_vcpu_thread(cpu);
}
void task_settid(TaskState *ts)
--
2.50.1
