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/sh4/helper.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/target/sh4/helper.c b/target/sh4/helper.c index 1e32365c75..c4d5b9a374 100644 --- a/target/sh4/helper.c +++ b/target/sh4/helper.c @@ -62,8 +62,11 @@ void superh_cpu_do_interrupt(CPUState *cs) { SuperHCPU *cpu = SUPERH_CPU(cs); CPUSH4State *env = &cpu->env; - int do_irq = cpu_interrupt_request(cs) & CPU_INTERRUPT_HARD; - int do_exp, irq_vector = cs->exception_index; + int do_irq; + int do_exp, irq_vector; + qemu_mutex_lock_iothread(); + do_irq = cpu_interrupt_request(cs) & CPU_INTERRUPT_HARD; + irq_vector = cs->exception_index; /* prioritize exceptions over interrupts */ @@ -79,9 +82,11 @@ void superh_cpu_do_interrupt(CPUState *cs) should be loaded with the kernel entry point. qemu_system_reset_request takes care of that. */ qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET); + qemu_mutex_unlock_iothread(); return; } if (do_irq && !env->in_sleep) { + qemu_mutex_unlock_iothread(); return; /* masked */ } } @@ -91,6 +96,7 @@ void superh_cpu_do_interrupt(CPUState *cs) irq_vector = sh_intc_get_pending_vector(env->intc_handle, (env->sr >> 4) & 0xf); if (irq_vector == -1) { + qemu_mutex_unlock_iothread(); return; /* masked */ } } @@ -180,14 +186,17 @@ void superh_cpu_do_interrupt(CPUState *cs) env->pc = env->vbr + 0x100; break; } + qemu_mutex_unlock_iothread(); return; } if (do_irq) { env->intevt = irq_vector; env->pc = env->vbr + 0x600; + qemu_mutex_unlock_iothread(); return; } + qemu_mutex_unlock_iothread(); } static void update_itlb_use(CPUSH4State * env, int itlbnb) -- 2.17.1
