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accel/tcg: Add cpu_in_serial_context

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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>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-10-26 14:58:09 +10:00
parent 1fceff9c3c
commit 9877ea05de
3 changed files with 13 additions and 1 deletions
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3
accel/tcg/cpu-exec-common.c
View File

@ -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);
}

9
accel/tcg/internal.h
View File

@ -64,6 +64,15 @@ static inline target_ulong log_pc(CPUState *cpu, const TranslationBlock *tb)
}
}
/*
* Return true if CS is not running in parallel with other cpus, either
* because there are no other cpus or we are within an exclusive context.
*/
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;

2
accel/tcg/tb-maint.c
View File

@ -760,7 +760,7 @@ void tb_flush(CPUState *cpu)
if (tcg_enabled()) {
unsigned tb_flush_count = qatomic_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,