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/mips/helper.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/target/mips/helper.c b/target/mips/helper.c index afd78b1990..6595d18702 100644 --- a/target/mips/helper.c +++ b/target/mips/helper.c @@ -1085,6 +1085,10 @@ static inline void set_badinstr_registers(CPUMIPSState *env) void mips_cpu_do_interrupt(CPUState *cs) { + bool bql = !qemu_mutex_iothread_locked(); + if (bql) { + qemu_mutex_lock_iothread(); + } #if !defined(CONFIG_USER_ONLY) MIPSCPU *cpu = MIPS_CPU(cs); CPUMIPSState *env = &cpu->env; @@ -1396,10 +1400,14 @@ void mips_cpu_do_interrupt(CPUState *cs) } #endif cs->exception_index = EXCP_NONE; + if (bql) { + qemu_mutex_unlock_iothread(); + } } bool mips_cpu_exec_interrupt(CPUState *cs, int interrupt_request) { + qemu_mutex_lock_iothread(); if (interrupt_request & CPU_INTERRUPT_HARD) { MIPSCPU *cpu = MIPS_CPU(cs); CPUMIPSState *env = &cpu->env; @@ -1410,9 +1418,11 @@ bool mips_cpu_exec_interrupt(CPUState *cs, int interrupt_request) cs->exception_index = EXCP_EXT_INTERRUPT; env->error_code = 0; mips_cpu_do_interrupt(cs); + qemu_mutex_unlock_iothread(); return true; } } + qemu_mutex_unlock_iothread(); return false; } -- 2.17.1
