This is part of a series of changes to remove the implied BQL from the common code of cpu_handle_interrupt and cpu_handle_exception. As part of removing the implied BQL from the common code, we are pushing the BQL holding down into the per-arch implementation functions of do_interrupt and cpu_exec_interrupt.
The purpose of this set of changes is to set the groundwork so that an arch could move towards removing the BQL from the cpu_handle_interrupt/exception paths. This approach was suggested by Paolo Bonzini. For reference, here are two key posts in the discussion, explaining the reasoning/benefits of this approach. https://lists.gnu.org/archive/html/qemu-devel/2020-07/msg08731.html https://lists.gnu.org/archive/html/qemu-devel/2020-08/msg00044.html Signed-off-by: Robert Foley <robert.fo...@linaro.org> --- target/alpha/helper.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/target/alpha/helper.c b/target/alpha/helper.c index 55d7274d94..18169ae1c5 100644 --- a/target/alpha/helper.c +++ b/target/alpha/helper.c @@ -299,8 +299,12 @@ void alpha_cpu_do_interrupt(CPUState *cs) { AlphaCPU *cpu = ALPHA_CPU(cs); CPUAlphaState *env = &cpu->env; - int i = cs->exception_index; - + int i; + bool bql = !qemu_mutex_iothread_locked(); + if (bql) { + qemu_mutex_lock_iothread(); + } + i = cs->exception_index; if (qemu_loglevel_mask(CPU_LOG_INT)) { static int count; const char *name = "<unknown>"; @@ -405,6 +409,9 @@ void alpha_cpu_do_interrupt(CPUState *cs) /* Switch to PALmode. */ env->flags |= ENV_FLAG_PAL_MODE; #endif /* !USER_ONLY */ + if (bql) { + qemu_mutex_unlock_iothread(); + } } bool alpha_cpu_exec_interrupt(CPUState *cs, int interrupt_request) @@ -412,9 +419,11 @@ bool alpha_cpu_exec_interrupt(CPUState *cs, int interrupt_request) AlphaCPU *cpu = ALPHA_CPU(cs); CPUAlphaState *env = &cpu->env; int idx = -1; + qemu_mutex_lock_iothread(); /* We never take interrupts while in PALmode. */ if (env->flags & ENV_FLAG_PAL_MODE) { + qemu_mutex_unlock_iothread(); return false; } @@ -446,8 +455,10 @@ bool alpha_cpu_exec_interrupt(CPUState *cs, int interrupt_request) cs->exception_index = idx; env->error_code = 0; alpha_cpu_do_interrupt(cs); + qemu_mutex_unlock_iothread(); return true; } + qemu_mutex_unlock_iothread(); return false; } -- 2.17.1
