[v4,09/54] cpu: introduce cpu_in_exclusive_context()

Commit Message

Alex Bennée July 31, 2019, 4:06 p.m. UTC

From: "Emilio G. Cota" <[e-mail]>

Suggested-by: Alex Bennée <[e-mail]>
Reviewed-by: Alex Bennée <[e-mail]>
Signed-off-by: Emilio G. Cota <[e-mail]>
[AJB: moved inside start/end_exclusive fns + cleanup]
Signed-off-by: Alex Bennée <[e-mail]>

---
v4
  - -> cpu_in_exclusive_context
  - moved inside start/end exclusive
  - fixed up cpu_exec_step_atomic
---
 accel/tcg/cpu-exec.c |  5 +----
 cpus-common.c        |  4 ++++
 include/qom/cpu.h    | 13 +++++++++++++
 3 files changed, 18 insertions(+), 4 deletions(-)

Comments

Richard Henderson Aug. 1, 2019, 3:23 p.m. UTC | #1

On 7/31/19 9:06 AM, Alex Bennée wrote:
> From: "Emilio G. Cota" <[e-mail]>
> 
> Suggested-by: Alex Bennée <[e-mail]>
> Reviewed-by: Alex Bennée <[e-mail]>
> Signed-off-by: Emilio G. Cota <[e-mail]>
> [AJB: moved inside start/end_exclusive fns + cleanup]
> Signed-off-by: Alex Bennée <[e-mail]>
> 
> ---
> v4
>   - -> cpu_in_exclusive_context
>   - moved inside start/end exclusive
>   - fixed up cpu_exec_step_atomic
> ---
>  accel/tcg/cpu-exec.c |  5 +----
>  cpus-common.c        |  4 ++++
>  include/qom/cpu.h    | 13 +++++++++++++
>  3 files changed, 18 insertions(+), 4 deletions(-)

Reviewed-by: Richard Henderson <[e-mail]>


r~

Patch

diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index 6c85c3ee1e9..ab9dfd4f908 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -239,8 +239,6 @@  void cpu_exec_step_atomic(CPUState *cpu)
     uint32_t flags;
     uint32_t cflags = 1;
     uint32_t cf_mask = cflags & CF_HASH_MASK;
-    /* volatile because we modify it between setjmp and longjmp */
-    volatile bool in_exclusive_region = false;
 
     if (sigsetjmp(cpu->jmp_env, 0) == 0) {
         tb = tb_lookup__cpu_state(cpu, &pc, &cs_base, &flags, cf_mask);
@@ -254,7 +252,6 @@  void cpu_exec_step_atomic(CPUState *cpu)
 
         /* Since we got here, we know that parallel_cpus must be true.  */
         parallel_cpus = false;
-        in_exclusive_region = true;
         cc->cpu_exec_enter(cpu);
         /* execute the generated code */
         trace_exec_tb(tb, pc);
@@ -274,7 +271,7 @@  void cpu_exec_step_atomic(CPUState *cpu)
         assert_no_pages_locked();
     }
 
-    if (in_exclusive_region) {
+    if (cpu_in_exclusive_context(cpu)) {
         /* We might longjump out of either the codegen or the
          * execution, so must make sure we only end the exclusive
          * region if we started it.
diff --git a/cpus-common.c b/cpus-common.c
index 3ca58c64e80..e87400834be 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -208,11 +208,15 @@  void start_exclusive(void)
      * section until end_exclusive resets pending_cpus to 0.
      */
     qemu_mutex_unlock(&qemu_cpu_list_lock);
+
+    current_cpu->in_exclusive_context = true;
 }
 
 /* Finish an exclusive operation.  */
 void end_exclusive(void)
 {
+    current_cpu->in_exclusive_context = false;
+
     qemu_mutex_lock(&qemu_cpu_list_lock);
     atomic_set(&pending_cpus, 0);
     qemu_cond_broadcast(&exclusive_resume);
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 5ee0046b629..65a0926c49a 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -373,6 +373,7 @@  struct CPUState {
     bool unplug;
     bool crash_occurred;
     bool exit_request;
+    bool in_exclusive_context;
     uint32_t cflags_next_tb;
     /* updates protected by BQL */
     uint32_t interrupt_request;
@@ -785,6 +786,18 @@  void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
  */
 void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data);
 
+/**
+ * cpu_in_exclusive_context()
+ * @cpu: The vCPU to check
+ *
+ * Returns true if @cpu is an exclusive context, for example running
+ * something which has previously been queued via async_safe_run_on_cpu().
+ */
+static inline bool cpu_in_exclusive_context(const CPUState *cpu)
+{
+    return cpu->in_exclusive_context;
+}
+
 /**
  * qemu_get_cpu:
  * @index: The CPUState@cpu_index value of the CPU to obtain.