From 0d58c660689f6da1e3feff8a997014003d928b3b Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Fri, 25 Aug 2023 16:13:17 -0700 Subject: softmmu: Use async_run_on_cpu in tcg_commit MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit After system startup, run the update to memory_dispatch and the tlb_flush on the cpu. This eliminates a race, wherein a running cpu sees the memory_dispatch change but has not yet seen the tlb_flush. Since the update now happens on the cpu, we need not use qatomic_rcu_read to protect the read of memory_dispatch. Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1826 Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1834 Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1846 Tested-by: Alex Bennée Reviewed-by: Alex Bennée Signed-off-by: Richard Henderson --- accel/tcg/cpu-exec-common.c | 30 ------------------------------ 1 file changed, 30 deletions(-) (limited to 'accel/tcg/cpu-exec-common.c') diff --git a/accel/tcg/cpu-exec-common.c b/accel/tcg/cpu-exec-common.c index 9a5fabf625..7e35d7f4b5 100644 --- a/accel/tcg/cpu-exec-common.c +++ b/accel/tcg/cpu-exec-common.c @@ -33,36 +33,6 @@ void cpu_loop_exit_noexc(CPUState *cpu) cpu_loop_exit(cpu); } -#if defined(CONFIG_SOFTMMU) -void cpu_reloading_memory_map(void) -{ - if (qemu_in_vcpu_thread() && current_cpu->running) { - /* The guest can in theory prolong the RCU critical section as long - * as it feels like. The major problem with this is that because it - * can do multiple reconfigurations of the memory map within the - * critical section, we could potentially accumulate an unbounded - * collection of memory data structures awaiting reclamation. - * - * Because the only thing we're currently protecting with RCU is the - * memory data structures, it's sufficient to break the critical section - * in this callback, which we know will get called every time the - * memory map is rearranged. - * - * (If we add anything else in the system that uses RCU to protect - * its data structures, we will need to implement some other mechanism - * to force TCG CPUs to exit the critical section, at which point this - * part of this callback might become unnecessary.) - * - * This pair matches cpu_exec's rcu_read_lock()/rcu_read_unlock(), which - * only protects cpu->as->dispatch. Since we know our caller is about - * to reload it, it's safe to split the critical section. - */ - rcu_read_unlock(); - rcu_read_lock(); - } -} -#endif - void cpu_loop_exit(CPUState *cpu) { /* Undo the setting in cpu_tb_exec. */ -- cgit 1.4.1