This eliminates the need to use the BQL to queue CPU work.
While at it, give the per-cpu field a generic name ("cond") since
it will soon be used for more than just queueing CPU work.
Cc: Peter Crosthwaite <crosthwaite.pe...@gmail.com>
Cc: Richard Henderson <r...@twiddle.net>
Signed-off-by: Emilio G. Cota <c...@braap.org>
---
include/qom/cpu.h | 6 +++---
cpus-common.c | 48 ++++++++++++++++++++++++++++++++++-------------
cpus.c | 2 +-
qom/cpu.c | 1 +
4 files changed, 40 insertions(+), 17 deletions(-)
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 1292e7aa33..82937881ef 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -316,6 +316,7 @@ struct qemu_work_item;
* @mem_io_vaddr: Target virtual address at which the memory was accessed.
* @kvm_fd: vCPU file descriptor for KVM.
* @lock: Lock to prevent multiple access to per-CPU fields.
+ * @cond: Condition variable for per-CPU events.
* @work_list: List of pending asynchronous work.
* @trace_dstate_delayed: Delayed changes to trace_dstate (includes all changes
* to @trace_dstate).
@@ -358,6 +359,7 @@ struct CPUState {
QemuMutex lock;
/* fields below protected by @lock */
+ QemuCond cond;
QSIMPLEQ_HEAD(, qemu_work_item) work_list;
CPUAddressSpace *cpu_ases;
@@ -762,12 +764,10 @@ bool cpu_is_stopped(CPUState *cpu);
* @cpu: The vCPU to run on.
* @func: The function to be executed.
* @data: Data to pass to the function.
- * @mutex: Mutex to release while waiting for @func to run.
*
* Used internally in the implementation of run_on_cpu.
*/
-void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data,
- QemuMutex *mutex);
+void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data);
/**
* run_on_cpu:
diff --git a/cpus-common.c b/cpus-common.c
index 2913294cb7..2881707c35 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -26,7 +26,6 @@
static QemuMutex qemu_cpu_list_lock;
static QemuCond exclusive_cond;
static QemuCond exclusive_resume;
-static QemuCond qemu_work_cond;
/* >= 1 if a thread is inside start_exclusive/end_exclusive. Written
* under qemu_cpu_list_lock, read with atomic operations.
@@ -42,7 +41,6 @@ void qemu_init_cpu_list(void)
qemu_mutex_init(&qemu_cpu_list_lock);
qemu_cond_init(&exclusive_cond);
qemu_cond_init(&exclusive_resume);
- qemu_cond_init(&qemu_work_cond);
}
void cpu_list_lock(void)
@@ -113,39 +111,52 @@ struct qemu_work_item {
bool free, exclusive, done;
};
-static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi)
+/* Called with the CPU's lock held */
+static void queue_work_on_cpu_locked(CPUState *cpu, struct qemu_work_item *wi)
{
- qemu_mutex_lock(&cpu->lock);
QSIMPLEQ_INSERT_TAIL(&cpu->work_list, wi, node);
wi->done = false;
- qemu_mutex_unlock(&cpu->lock);
qemu_cpu_kick(cpu);
}
-void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data,
- QemuMutex *mutex)
+static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi)
+{
+ cpu_mutex_lock(cpu);
+ queue_work_on_cpu_locked(cpu, wi);
+ cpu_mutex_unlock(cpu);
+}
+
+void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
{
struct qemu_work_item wi;
+ g_assert(qemu_mutex_iothread_locked());
+
if (qemu_cpu_is_self(cpu)) {
func(cpu, data);
return;
}
+ qemu_mutex_unlock_iothread();
+
wi.func = func;
wi.data = data;
wi.done = false;
wi.free = false;
wi.exclusive = false;
- queue_work_on_cpu(cpu, &wi);
+ cpu_mutex_lock(cpu);
+ queue_work_on_cpu_locked(cpu, &wi);
while (!atomic_mb_read(&wi.done)) {
CPUState *self_cpu = current_cpu;
- qemu_cond_wait(&qemu_work_cond, mutex);
+ qemu_cond_wait(&cpu->cond, &cpu->lock);
current_cpu = self_cpu;
}
+ cpu_mutex_unlock(cpu);
+
+ qemu_mutex_lock_iothread();
}
void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data
data)
@@ -307,6 +318,7 @@ void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func
func,
void process_queued_cpu_work(CPUState *cpu)
{
struct qemu_work_item *wi;
+ bool has_bql = qemu_mutex_iothread_locked();
qemu_mutex_lock(&cpu->lock);
if (QSIMPLEQ_EMPTY(&cpu->work_list)) {
@@ -324,13 +336,23 @@ void process_queued_cpu_work(CPUState *cpu)
* BQL, so it goes to sleep; start_exclusive() is sleeping too, so
* neither CPU can proceed.
*/
- qemu_mutex_unlock_iothread();
+ if (has_bql) {
+ qemu_mutex_unlock_iothread();
+ }
start_exclusive();
wi->func(cpu, wi->data);
end_exclusive();
- qemu_mutex_lock_iothread();
+ if (has_bql) {
+ qemu_mutex_lock_iothread();
+ }
} else {
- wi->func(cpu, wi->data);
+ if (has_bql) {
+ wi->func(cpu, wi->data);
+ } else {
+ qemu_mutex_lock_iothread();
+ wi->func(cpu, wi->data);
+ qemu_mutex_unlock_iothread();
+ }
}
qemu_mutex_lock(&cpu->lock);
if (wi->free) {
@@ -340,5 +362,5 @@ void process_queued_cpu_work(CPUState *cpu)
}
}
qemu_mutex_unlock(&cpu->lock);
- qemu_cond_broadcast(&qemu_work_cond);
+ qemu_cond_broadcast(&cpu->cond);
}
diff --git a/cpus.c b/cpus.c
index a190651653..e844335386 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1236,7 +1236,7 @@ void qemu_init_cpu_loop(void)
void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
{
- do_run_on_cpu(cpu, func, data, &qemu_global_mutex);
+ do_run_on_cpu(cpu, func, data);
}
static void qemu_kvm_destroy_vcpu(CPUState *cpu)
diff --git a/qom/cpu.c b/qom/cpu.c
index d0758c907d..bb031a3a6a 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -373,6 +373,7 @@ static void cpu_common_initfn(Object *obj)
cpu->nr_threads = 1;
qemu_mutex_init(&cpu->lock);
+ qemu_cond_init(&cpu->cond);
QSIMPLEQ_INIT(&cpu->work_list);
QTAILQ_INIT(&cpu->breakpoints);
QTAILQ_INIT(&cpu->watchpoints);
--
2.17.1
