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/i386/seg_helper.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/target/i386/seg_helper.c b/target/i386/seg_helper.c index 818f65f35f..114d4a0d24 100644 --- a/target/i386/seg_helper.c +++ b/target/i386/seg_helper.c @@ -1284,7 +1284,7 @@ void x86_cpu_do_interrupt(CPUState *cs) { X86CPU *cpu = X86_CPU(cs); CPUX86State *env = &cpu->env; - + qemu_mutex_lock_iothread(); #if defined(CONFIG_USER_ONLY) /* if user mode only, we simulate a fake exception which will be handled outside the cpu execution @@ -1308,6 +1308,7 @@ void x86_cpu_do_interrupt(CPUState *cs) env->old_exception = -1; } #endif + qemu_mutex_unlock_iothread(); } void do_interrupt_x86_hardirq(CPUX86State *env, int intno, int is_hw) @@ -1320,9 +1321,10 @@ bool x86_cpu_exec_interrupt(CPUState *cs, int interrupt_request) X86CPU *cpu = X86_CPU(cs); CPUX86State *env = &cpu->env; int intno; - + qemu_mutex_lock_iothread(); interrupt_request = x86_cpu_pending_interrupt(cs, interrupt_request); if (!interrupt_request) { + qemu_mutex_unlock_iothread(); return false; } @@ -1377,6 +1379,7 @@ bool x86_cpu_exec_interrupt(CPUState *cs, int interrupt_request) } /* Ensure that no TB jump will be modified as the program flow was changed. */ + qemu_mutex_unlock_iothread(); return true; } -- 2.17.1
