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/unicore32/helper.c | 3 +++ target/unicore32/softmmu.c | 7 +++++++ 2 files changed, 10 insertions(+) diff --git a/target/unicore32/helper.c b/target/unicore32/helper.c index 54c26871fe..d79284d224 100644 --- a/target/unicore32/helper.c +++ b/target/unicore32/helper.c @@ -169,6 +169,7 @@ void helper_cp1_putc(target_ulong regval) bool uc32_cpu_exec_interrupt(CPUState *cs, int interrupt_request) { + qemu_mutex_lock_iothread(); if (interrupt_request & CPU_INTERRUPT_HARD) { UniCore32CPU *cpu = UNICORE32_CPU(cs); CPUUniCore32State *env = &cpu->env; @@ -176,8 +177,10 @@ bool uc32_cpu_exec_interrupt(CPUState *cs, int interrupt_request) if (!(env->uncached_asr & ASR_I)) { cs->exception_index = UC32_EXCP_INTR; uc32_cpu_do_interrupt(cs); + qemu_mutex_unlock_iothread(); return true; } } + qemu_mutex_unlock_iothread(); return false; } diff --git a/target/unicore32/softmmu.c b/target/unicore32/softmmu.c index 9660bd2a27..ca9b92aad0 100644 --- a/target/unicore32/softmmu.c +++ b/target/unicore32/softmmu.c @@ -81,6 +81,10 @@ void uc32_cpu_do_interrupt(CPUState *cs) CPUUniCore32State *env = &cpu->env; uint32_t addr; int new_mode; + bool bql = !qemu_mutex_iothread_locked(); + if (bql) { + qemu_mutex_lock_iothread(); + } switch (cs->exception_index) { case UC32_EXCP_PRIV: @@ -118,6 +122,9 @@ void uc32_cpu_do_interrupt(CPUState *cs) env->regs[30] = env->regs[31]; env->regs[31] = addr; cpu_interrupt_request_or(cs, CPU_INTERRUPT_EXITTB); + if (bql) { + qemu_mutex_unlock_iothread(); + } } static int get_phys_addr_ucv2(CPUUniCore32State *env, uint32_t address, -- 2.17.1
