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/microblaze/helper.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/target/microblaze/helper.c b/target/microblaze/helper.c index ab2ceeb055..ae8ff2bea4 100644 --- a/target/microblaze/helper.c +++ b/target/microblaze/helper.c @@ -32,10 +32,17 @@ void mb_cpu_do_interrupt(CPUState *cs) { MicroBlazeCPU *cpu = MICROBLAZE_CPU(cs); CPUMBState *env = &cpu->env; + bool bql = !qemu_mutex_iothread_locked(); + if (bql) { + qemu_mutex_lock_iothread(); + } cs->exception_index = -1; env->res_addr = RES_ADDR_NONE; env->regs[14] = env->sregs[SR_PC]; + if (bql) { + qemu_mutex_unlock_iothread(); + } } bool mb_cpu_tlb_fill(CPUState *cs, vaddr address, int size, @@ -113,6 +120,10 @@ void mb_cpu_do_interrupt(CPUState *cs) MicroBlazeCPU *cpu = MICROBLAZE_CPU(cs); CPUMBState *env = &cpu->env; uint32_t t; + bool bql = !qemu_mutex_iothread_locked(); + if (bql) { + qemu_mutex_lock_iothread(); + } /* IMM flag cannot propagate across a branch and into the dslot. */ assert(!((env->iflags & D_FLAG) && (env->iflags & IMM_FLAG))); @@ -123,6 +134,9 @@ void mb_cpu_do_interrupt(CPUState *cs) case EXCP_HW_EXCP: if (!(env->pvr.regs[0] & PVR0_USE_EXC_MASK)) { qemu_log_mask(LOG_GUEST_ERROR, "Exception raised on system without exceptions!\n"); + if (bql) { + qemu_mutex_unlock_iothread(); + } return; } @@ -262,6 +276,9 @@ void mb_cpu_do_interrupt(CPUState *cs) cs->exception_index); break; } + if (bql) { + qemu_mutex_unlock_iothread(); + } } hwaddr mb_cpu_get_phys_page_debug(CPUState *cs, vaddr addr) @@ -291,6 +308,7 @@ bool mb_cpu_exec_interrupt(CPUState *cs, int interrupt_request) { MicroBlazeCPU *cpu = MICROBLAZE_CPU(cs); CPUMBState *env = &cpu->env; + qemu_mutex_lock_iothread(); if ((interrupt_request & CPU_INTERRUPT_HARD) && (env->sregs[SR_MSR] & MSR_IE) @@ -298,7 +316,9 @@ bool mb_cpu_exec_interrupt(CPUState *cs, int interrupt_request) && !(env->iflags & (D_FLAG | IMM_FLAG))) { cs->exception_index = EXCP_IRQ; mb_cpu_do_interrupt(cs); + qemu_mutex_unlock_iothread(); return true; } + qemu_mutex_unlock_iothread(); return false; } -- 2.17.1
