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tcg: Make tb_flush() thread safe

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Use async_safe_run_on_cpu() to make tb_flush() thread safe.  This is
possible now that code generation does not happen in the middle of
execution.

It can happen that multiple threads schedule a safe work to flush the
translation buffer. To keep statistics and debugging output sane, always
check if the translation buffer has already been flushed.

Signed-off-by: Sergey Fedorov <serge.fdrv@gmail.com>
Signed-off-by: Sergey Fedorov <sergey.fedorov@linaro.org>
[AJB: minor re-base fixes]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <1470158864-17651-13-git-send-email-alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sergey Fedorov 2016-08-02 18:27:43 +01:00 • committed by Paolo Bonzini
parent 53f5ed9506
commit 3359baad36
4 changed files with 31 additions and 23 deletions
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12
cpu-exec.c
View file

@ -204,20 +204,16 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
TranslationBlock *orig_tb, bool ignore_icount)
{
TranslationBlock *tb;
bool old_tb_flushed;
/* Should never happen.
We only end up here when an existing TB is too long. */
if (max_cycles > CF_COUNT_MASK)
max_cycles = CF_COUNT_MASK;
old_tb_flushed = cpu->tb_flushed;
cpu->tb_flushed = false;
tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base, orig_tb->flags,
max_cycles | CF_NOCACHE
| (ignore_icount ? CF_IGNORE_ICOUNT : 0));
tb->orig_tb = cpu->tb_flushed ? NULL : orig_tb;
cpu->tb_flushed |= old_tb_flushed;
tb->orig_tb = orig_tb;
/* execute the generated code */
trace_exec_tb_nocache(tb, tb->pc);
cpu_tb_exec(cpu, tb);
@ -338,10 +334,7 @@ static inline TranslationBlock *tb_find(CPUState *cpu,
tb_lock();
have_tb_lock = true;
}
/* Check if translation buffer has been flushed */
if (cpu->tb_flushed) {
cpu->tb_flushed = false;
} else if (!tb->invalid) {
if (!tb->invalid) {
tb_add_jump(last_tb, tb_exit, tb);
}
}
@ -606,7 +599,6 @@ int cpu_exec(CPUState *cpu)
break;
}
atomic_mb_set(&cpu->tb_flushed, false); /* reset before first TB lookup */
for(;;) {
cpu_handle_interrupt(cpu, &last_tb);
tb = tb_find(cpu, last_tb, tb_exit);