diff mbox series

[v3,02/57] accel/tcg: Add cpu_in_serial_context

Message ID 20230425193146.2106111-3-richard.henderson@linaro.org
State Superseded
Headers show
Series tcg: Improve atomicity support | expand

Commit Message

Richard Henderson April 25, 2023, 7:30 p.m. UTC 
Like cpu_in_exclusive_context, but also true if
there is no other cpu against which we could race.

Use it in tb_flush as a direct replacement.
Use it in cpu_loop_exit_atomic to ensure that there
is no loop against cpu_exec_step_atomic.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/internal.h        | 5 +++++
 accel/tcg/cpu-exec-common.c | 3 +++
 accel/tcg/tb-maint.c        | 2 +-
 3 files changed, 9 insertions(+), 1 deletion(-)

Comments

Peter Maydell May 4, 2023, 2:52 p.m. UTC | #1 
On Tue, 25 Apr 2023 at 20:33, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Like cpu_in_exclusive_context, but also true if
> there is no other cpu against which we could race.
>
> Use it in tb_flush as a direct replacement.
> Use it in cpu_loop_exit_atomic to ensure that there
> is no loop against cpu_exec_step_atomic.
>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  accel/tcg/internal.h        | 5 +++++
>  accel/tcg/cpu-exec-common.c | 3 +++
>  accel/tcg/tb-maint.c        | 2 +-
>  3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/accel/tcg/internal.h b/accel/tcg/internal.h
> index 96f198b28b..8250ecbf74 100644
> --- a/accel/tcg/internal.h
> +++ b/accel/tcg/internal.h
> @@ -64,6 +64,11 @@ static inline target_ulong log_pc(CPUState *cpu, const TranslationBlock *tb)
>      }
>  }
>
> +static inline bool cpu_in_serial_context(CPUState *cs)
> +{
> +    return !(cs->tcg_cflags & CF_PARALLEL) || cpu_in_exclusive_context(cs);
> +}

Can we have a doc comment that defines the semantics, please?
Otherwise
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM
diff mbox series

Patch

diff --git a/accel/tcg/internal.h b/accel/tcg/internal.h
index 96f198b28b..8250ecbf74 100644
--- a/accel/tcg/internal.h
+++ b/accel/tcg/internal.h
@@ -64,6 +64,11 @@  static inline target_ulong log_pc(CPUState *cpu, const TranslationBlock *tb)
     }
 }
 
+static inline bool cpu_in_serial_context(CPUState *cs)
+{
+    return !(cs->tcg_cflags & CF_PARALLEL) || cpu_in_exclusive_context(cs);
+}
+
 extern int64_t max_delay;
 extern int64_t max_advance;
 
diff --git a/accel/tcg/cpu-exec-common.c b/accel/tcg/cpu-exec-common.c
index e7962c9348..9a5fabf625 100644
--- a/accel/tcg/cpu-exec-common.c
+++ b/accel/tcg/cpu-exec-common.c
@@ -22,6 +22,7 @@ 
 #include "sysemu/tcg.h"
 #include "exec/exec-all.h"
 #include "qemu/plugin.h"
+#include "internal.h"
 
 bool tcg_allowed;
 
@@ -81,6 +82,8 @@  void cpu_loop_exit_restore(CPUState *cpu, uintptr_t pc)
 
 void cpu_loop_exit_atomic(CPUState *cpu, uintptr_t pc)
 {
+    /* Prevent looping if already executing in a serial context. */
+    g_assert(!cpu_in_serial_context(cpu));
     cpu->exception_index = EXCP_ATOMIC;
     cpu_loop_exit_restore(cpu, pc);
 }
diff --git a/accel/tcg/tb-maint.c b/accel/tcg/tb-maint.c
index cb1f806f00..7d613d36d2 100644
--- a/accel/tcg/tb-maint.c
+++ b/accel/tcg/tb-maint.c
@@ -760,7 +760,7 @@  void tb_flush(CPUState *cpu)
     if (tcg_enabled()) {
         unsigned tb_flush_count = qatomic_mb_read(&tb_ctx.tb_flush_count);
 
-        if (cpu_in_exclusive_context(cpu)) {
+        if (cpu_in_serial_context(cpu)) {
             do_tb_flush(cpu, RUN_ON_CPU_HOST_INT(tb_flush_count));
         } else {
             async_safe_run_on_cpu(cpu, do_tb_flush,