diff options
| -rw-r--r-- | accel/tcg/cpu-exec-common.c | 30 | ||||
| -rw-r--r-- | include/exec/cpu-common.h | 1 | ||||
| -rw-r--r-- | softmmu/physmem.c | 40 |
3 files changed, 29 insertions, 42 deletions
diff --git a/accel/tcg/cpu-exec-common.c b/accel/tcg/cpu-exec-common.c index 9a5fabf..7e35d7f 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. */ diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h index 87dc9a7..41788c0 100644 --- a/include/exec/cpu-common.h +++ b/include/exec/cpu-common.h @@ -133,7 +133,6 @@ static inline void cpu_physical_memory_write(hwaddr addr, { cpu_physical_memory_rw(addr, (void *)buf, len, true); } -void cpu_reloading_memory_map(void); void *cpu_physical_memory_map(hwaddr addr, hwaddr *plen, bool is_write); diff --git a/softmmu/physmem.c b/softmmu/physmem.c index 7597dc1..18277dd 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -680,8 +680,7 @@ address_space_translate_for_iotlb(CPUState *cpu, int asidx, hwaddr orig_addr, IOMMUTLBEntry iotlb; int iommu_idx; hwaddr addr = orig_addr; - AddressSpaceDispatch *d = - qatomic_rcu_read(&cpu->cpu_ases[asidx].memory_dispatch); + AddressSpaceDispatch *d = cpu->cpu_ases[asidx].memory_dispatch; for (;;) { section = address_space_translate_internal(d, addr, &addr, plen, false); @@ -2412,7 +2411,7 @@ MemoryRegionSection *iotlb_to_section(CPUState *cpu, { int asidx = cpu_asidx_from_attrs(cpu, attrs); CPUAddressSpace *cpuas = &cpu->cpu_ases[asidx]; - AddressSpaceDispatch *d = qatomic_rcu_read(&cpuas->memory_dispatch); + AddressSpaceDispatch *d = cpuas->memory_dispatch; int section_index = index & ~TARGET_PAGE_MASK; MemoryRegionSection *ret; @@ -2487,23 +2486,42 @@ static void tcg_log_global_after_sync(MemoryListener *listener) } } +static void tcg_commit_cpu(CPUState *cpu, run_on_cpu_data data) +{ + CPUAddressSpace *cpuas = data.host_ptr; + + cpuas->memory_dispatch = address_space_to_dispatch(cpuas->as); + tlb_flush(cpu); +} + static void tcg_commit(MemoryListener *listener) { CPUAddressSpace *cpuas; - AddressSpaceDispatch *d; + CPUState *cpu; assert(tcg_enabled()); /* since each CPU stores ram addresses in its TLB cache, we must reset the modified entries */ cpuas = container_of(listener, CPUAddressSpace, tcg_as_listener); - cpu_reloading_memory_map(); - /* The CPU and TLB are protected by the iothread lock. - * We reload the dispatch pointer now because cpu_reloading_memory_map() - * may have split the RCU critical section. + cpu = cpuas->cpu; + + /* + * Defer changes to as->memory_dispatch until the cpu is quiescent. + * Otherwise we race between (1) other cpu threads and (2) ongoing + * i/o for the current cpu thread, with data cached by mmu_lookup(). + * + * In addition, queueing the work function will kick the cpu back to + * the main loop, which will end the RCU critical section and reclaim + * the memory data structures. + * + * That said, the listener is also called during realize, before + * all of the tcg machinery for run-on is initialized: thus halt_cond. */ - d = address_space_to_dispatch(cpuas->as); - qatomic_rcu_set(&cpuas->memory_dispatch, d); - tlb_flush(cpuas->cpu); + if (cpu->halt_cond) { + async_run_on_cpu(cpu, tcg_commit_cpu, RUN_ON_CPU_HOST_PTR(cpuas)); + } else { + tcg_commit_cpu(cpu, RUN_ON_CPU_HOST_PTR(cpuas)); + } } static void memory_map_init(void) |