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tcg: drop global lock during TCG code execution 

This finally allows TCG to benefit from the iothread introduction: Drop
the global mutex while running pure TCG CPU code. Reacquire the lock
when entering MMIO or PIO emulation, or when leaving the TCG loop.

We have to revert a few optimization for the current TCG threading
model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not
kicking it in qemu_cpu_kick. We also need to disable RAM block
reordering until we have a more efficient locking mechanism at hand.

Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here.
These numbers demonstrate where we gain something:

20338 jan       20   0  331m  75m 6904 R   99  0.9   0:50.95 qemu-system-arm
20337 jan       20   0  331m  75m 6904 S   20  0.9   0:26.50 qemu-system-arm

The guest CPU was fully loaded, but the iothread could still run mostly
independent on a second core. Without the patch we don't get beyond

32206 jan       20   0  330m  73m 7036 R   82  0.9   1:06.00 qemu-system-arm
32204 jan       20   0  330m  73m 7036 S   21  0.9   0:17.03 qemu-system-arm

We don't benefit significantly, though, when the guest is not fully
loading a host CPU.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com>
[FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex]
Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
[EGC: fixed iothread lock for cpu-exec IRQ handling]
Signed-off-by: Emilio G. Cota <cota@braap.org>
[AJB: -smp single-threaded fix, clean commit msg, BQL fixes]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
[PM: target-arm changes]
Acked-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Jan Kiszka 2017-02-23 18:29:11 +00:00 committed by Alex Bennée
parent 791158d93b
commit 8d04fb55de
18 changed files with 166 additions and 49 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
cpu-exec.c
View File

@ -29,6 +29,7 @@
#include "qemu/rcu.h"
#include "exec/tb-hash.h"
#include "exec/log.h"
#include "qemu/main-loop.h"
#if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
#include "hw/i386/apic.h"
#endif
@ -388,8 +389,10 @@ static inline bool cpu_handle_halt(CPUState *cpu)
if ((cpu->interrupt_request & CPU_INTERRUPT_POLL)
&& replay_interrupt()) {
X86CPU *x86_cpu = X86_CPU(cpu);
qemu_mutex_lock_iothread();
apic_poll_irq(x86_cpu->apic_state);
cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL);
qemu_mutex_unlock_iothread();
}
#endif
if (!cpu_has_work(cpu)) {
@ -443,7 +446,9 @@ static inline bool cpu_handle_exception(CPUState *cpu, int *ret)
#else
if (replay_exception()) {
CPUClass *cc = CPU_GET_CLASS(cpu);
qemu_mutex_lock_iothread();
cc->do_interrupt(cpu);
qemu_mutex_unlock_iothread();
cpu->exception_index = -1;
} else if (!replay_has_interrupt()) {
/* give a chance to iothread in replay mode */
@ -469,9 +474,11 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
TranslationBlock **last_tb)
{
CPUClass *cc = CPU_GET_CLASS(cpu);
int interrupt_request = cpu->interrupt_request;
if (unlikely(interrupt_request)) {
if (unlikely(atomic_read(&cpu->interrupt_request))) {
int interrupt_request;
qemu_mutex_lock_iothread();
interrupt_request = cpu->interrupt_request;
if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) {
/* Mask out external interrupts for this step. */
interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
@ -479,6 +486,7 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
if (interrupt_request & CPU_INTERRUPT_DEBUG) {
cpu->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
cpu->exception_index = EXCP_DEBUG;
qemu_mutex_unlock_iothread();
return true;
}
if (replay_mode == REPLAY_MODE_PLAY && !replay_has_interrupt()) {
@ -488,6 +496,7 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
cpu->interrupt_request &= ~CPU_INTERRUPT_HALT;
cpu->halted = 1;
cpu->exception_index = EXCP_HLT;
qemu_mutex_unlock_iothread();
return true;
}
#if defined(TARGET_I386)
@ -498,12 +507,14 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
cpu_svm_check_intercept_param(env, SVM_EXIT_INIT, 0, 0);
do_cpu_init(x86_cpu);
cpu->exception_index = EXCP_HALTED;
qemu_mutex_unlock_iothread();
return true;
}
#else
else if (interrupt_request & CPU_INTERRUPT_RESET) {
replay_interrupt();
cpu_reset(cpu);
qemu_mutex_unlock_iothread();
return true;
}
#endif
@ -526,7 +537,12 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
the program flow was changed */
*last_tb = NULL;
}
/* If we exit via cpu_loop_exit/longjmp it is reset in cpu_exec */
qemu_mutex_unlock_iothread();
}
if (unlikely(atomic_read(&cpu->exit_request) || replay_has_interrupt())) {
atomic_set(&cpu->exit_request, 0);
cpu->exception_index = EXCP_INTERRUPT;
@ -643,6 +659,9 @@ int cpu_exec(CPUState *cpu)
#endif /* buggy compiler */
cpu->can_do_io = 1;
tb_lock_reset();
if (qemu_mutex_iothread_locked()) {
qemu_mutex_unlock_iothread();
}
}
/* if an exception is pending, we execute it here */

28
cpus.c
View File

@ -1027,8 +1027,6 @@ static void qemu_kvm_init_cpu_signals(CPUState *cpu)
#endif /* _WIN32 */
static QemuMutex qemu_global_mutex;
static QemuCond qemu_io_proceeded_cond;
static unsigned iothread_requesting_mutex;
static QemuThread io_thread;
@ -1042,7 +1040,6 @@ void qemu_init_cpu_loop(void)
qemu_init_sigbus();
qemu_cond_init(&qemu_cpu_cond);
qemu_cond_init(&qemu_pause_cond);
qemu_cond_init(&qemu_io_proceeded_cond);
qemu_mutex_init(&qemu_global_mutex);
qemu_thread_get_self(&io_thread);
@ -1085,10 +1082,6 @@ static void qemu_tcg_wait_io_event(CPUState *cpu)
start_tcg_kick_timer();
while (iothread_requesting_mutex) {
qemu_cond_wait(&qemu_io_proceeded_cond, &qemu_global_mutex);
}
CPU_FOREACH(cpu) {
qemu_wait_io_event_common(cpu);
}
@ -1249,9 +1242,11 @@ static int tcg_cpu_exec(CPUState *cpu)
cpu->icount_decr.u16.low = decr;
cpu->icount_extra = count;
}
qemu_mutex_unlock_iothread();
cpu_exec_start(cpu);
ret = cpu_exec(cpu);
cpu_exec_end(cpu);
qemu_mutex_lock_iothread();
#ifdef CONFIG_PROFILER
tcg_time += profile_getclock() - ti;
#endif
@ -1479,27 +1474,14 @@ bool qemu_mutex_iothread_locked(void)
void qemu_mutex_lock_iothread(void)
{
atomic_inc(&iothread_requesting_mutex);
/* In the simple case there is no need to bump the VCPU thread out of
* TCG code execution.
*/
if (!tcg_enabled() || qemu_in_vcpu_thread() ||
!first_cpu || !first_cpu->created) {
qemu_mutex_lock(&qemu_global_mutex);
atomic_dec(&iothread_requesting_mutex);
} else {
if (qemu_mutex_trylock(&qemu_global_mutex)) {
qemu_cpu_kick_rr_cpu();
qemu_mutex_lock(&qemu_global_mutex);
}
atomic_dec(&iothread_requesting_mutex);
qemu_cond_broadcast(&qemu_io_proceeded_cond);
}
g_assert(!qemu_mutex_iothread_locked());
qemu_mutex_lock(&qemu_global_mutex);
iothread_locked = true;
}
void qemu_mutex_unlock_iothread(void)
{
g_assert(qemu_mutex_iothread_locked());
iothread_locked = false;
qemu_mutex_unlock(&qemu_global_mutex);
}

21
cputlb.c
View File

@ -18,6 +18,7 @@
*/
#include "qemu/osdep.h"
#include "qemu/main-loop.h"
#include "cpu.h"
#include "exec/exec-all.h"
#include "exec/memory.h"
@ -495,6 +496,7 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
hwaddr physaddr = iotlbentry->addr;
MemoryRegion *mr = iotlb_to_region(cpu, physaddr, iotlbentry->attrs);
uint64_t val;
bool locked = false;
physaddr = (physaddr & TARGET_PAGE_MASK) + addr;
cpu->mem_io_pc = retaddr;
@ -503,7 +505,16 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
}
cpu->mem_io_vaddr = addr;
if (mr->global_locking) {
qemu_mutex_lock_iothread();
locked = true;
}
memory_region_dispatch_read(mr, physaddr, &val, size, iotlbentry->attrs);
if (locked) {
qemu_mutex_unlock_iothread();
}
return val;
}
@ -514,15 +525,23 @@ static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
CPUState *cpu = ENV_GET_CPU(env);
hwaddr physaddr = iotlbentry->addr;
MemoryRegion *mr = iotlb_to_region(cpu, physaddr, iotlbentry->attrs);
bool locked = false;
physaddr = (physaddr & TARGET_PAGE_MASK) + addr;
if (mr != &io_mem_rom && mr != &io_mem_notdirty && !cpu->can_do_io) {
cpu_io_recompile(cpu, retaddr);
}
cpu->mem_io_vaddr = addr;
cpu->mem_io_pc = retaddr;
if (mr->global_locking) {
qemu_mutex_lock_iothread();
locked = true;
}
memory_region_dispatch_write(mr, physaddr, val, size, iotlbentry->attrs);
if (locked) {
qemu_mutex_unlock_iothread();
}
}
/* Return true if ADDR is present in the victim tlb, and has been copied

12
exec.c
View File

@ -2134,9 +2134,9 @@ static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags)
}
cpu->watchpoint_hit = wp;
/* The tb_lock will be reset when cpu_loop_exit or
* cpu_loop_exit_noexc longjmp back into the cpu_exec
* main loop.
/* Both tb_lock and iothread_mutex will be reset when
* cpu_loop_exit or cpu_loop_exit_noexc longjmp
* back into the cpu_exec main loop.
*/
tb_lock();
tb_check_watchpoint(cpu);
@ -2371,8 +2371,14 @@ static void io_mem_init(void)
memory_region_init_io(&io_mem_rom, NULL, &unassigned_mem_ops, NULL, NULL, UINT64_MAX);
memory_region_init_io(&io_mem_unassigned, NULL, &unassigned_mem_ops, NULL,
NULL, UINT64_MAX);
/* io_mem_notdirty calls tb_invalidate_phys_page_fast,
* which can be called without the iothread mutex.
*/
memory_region_init_io(&io_mem_notdirty, NULL, &notdirty_mem_ops, NULL,
NULL, UINT64_MAX);
memory_region_clear_global_locking(&io_mem_notdirty);
memory_region_init_io(&io_mem_watch, NULL, &watch_mem_ops, NULL,
NULL, UINT64_MAX);
}

1
hw/core/irq.c
View File

@ -22,6 +22,7 @@
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qemu/main-loop.h"
#include "qemu-common.h"
#include "hw/irq.h"
#include "qom/object.h"

4
hw/i386/kvmvapic.c
View File

@ -457,8 +457,8 @@ static void patch_instruction(VAPICROMState *s, X86CPU *cpu, target_ulong ip)
resume_all_vcpus();
if (!kvm_enabled()) {
/* tb_lock will be reset when cpu_loop_exit_noexc longjmps
* back into the cpu_exec loop. */
/* Both tb_lock and iothread_mutex will be reset when
* longjmps back into the cpu_exec loop. */
tb_lock();
tb_gen_code(cs, current_pc, current_cs_base, current_flags, 1);
cpu_loop_exit_noexc(cs);

3
hw/intc/arm_gicv3_cpuif.c
View File

@ -14,6 +14,7 @@
#include "qemu/osdep.h"
#include "qemu/bitops.h"
#include "qemu/main-loop.h"
#include "trace.h"
#include "gicv3_internal.h"
#include "cpu.h"
@ -733,6 +734,8 @@ void gicv3_cpuif_update(GICv3CPUState *cs)
ARMCPU *cpu = ARM_CPU(cs->cpu);
CPUARMState *env = &cpu->env;
g_assert(qemu_mutex_iothread_locked());
trace_gicv3_cpuif_update(gicv3_redist_affid(cs), cs->hppi.irq,
cs->hppi.grp, cs->hppi.prio);

16
hw/ppc/ppc.c
View File

@ -62,7 +62,16 @@ void ppc_set_irq(PowerPCCPU *cpu, int n_IRQ, int level)
{
CPUState *cs = CPU(cpu);
CPUPPCState *env = &cpu->env;
unsigned int old_pending = env->pending_interrupts;
unsigned int old_pending;
bool locked = false;
/* We may already have the BQL if coming from the reset path */
if (!qemu_mutex_iothread_locked()) {
locked = true;
qemu_mutex_lock_iothread();
}
old_pending = env->pending_interrupts;
if (level) {
env->pending_interrupts |= 1 << n_IRQ;
@ -80,9 +89,14 @@ void ppc_set_irq(PowerPCCPU *cpu, int n_IRQ, int level)
#endif
}
LOG_IRQ("%s: %p n_IRQ %d level %d => pending %08" PRIx32
"req %08x\n", __func__, env, n_IRQ, level,
env->pending_interrupts, CPU(cpu)->interrupt_request);
if (locked) {
qemu_mutex_unlock_iothread();
}
}
/* PowerPC 6xx / 7xx internal IRQ controller */

3
hw/ppc/spapr.c
View File

@ -1010,6 +1010,9 @@ static void emulate_spapr_hypercall(PPCVirtualHypervisor *vhyp,
{
CPUPPCState *env = &cpu->env;
/* The TCG path should also be holding the BQL at this point */
g_assert(qemu_mutex_iothread_locked());
if (msr_pr) {
hcall_dprintf("Hypercall made with MSR[PR]=1\n");
env->gpr[3] = H_PRIVILEGE;

1
include/qom/cpu.h
View File

@ -329,6 +329,7 @@ struct CPUState {
bool unplug;
bool crash_occurred;
bool exit_request;
/* updates protected by BQL */
uint32_t interrupt_request;
int singlestep_enabled;
int64_t icount_extra;

2
memory.c
View File

@ -917,6 +917,8 @@ void memory_region_transaction_commit(void)
AddressSpace *as;
assert(memory_region_transaction_depth);
assert(qemu_mutex_iothread_locked());
--memory_region_transaction_depth;
if (!memory_region_transaction_depth) {
if (memory_region_update_pending) {

10
qom/cpu.c
View File

@ -113,9 +113,19 @@ static void cpu_common_get_memory_mapping(CPUState *cpu,
error_setg(errp, "Obtaining memory mappings is unsupported on this CPU.");
}
/* Resetting the IRQ comes from across the code base so we take the
* BQL here if we need to. cpu_interrupt assumes it is held.*/
void cpu_reset_interrupt(CPUState *cpu, int mask)
{
bool need_lock = !qemu_mutex_iothread_locked();
if (need_lock) {
qemu_mutex_lock_iothread();
}
cpu->interrupt_request &= ~mask;
if (need_lock) {
qemu_mutex_unlock_iothread();
}
}
void cpu_exit(CPUState *cpu)

6
target/arm/helper.c
View File

@ -6769,6 +6769,12 @@ void arm_cpu_do_interrupt(CPUState *cs)
arm_cpu_do_interrupt_aarch32(cs);
}
/* Hooks may change global state so BQL should be held, also the
* BQL needs to be held for any modification of
* cs->interrupt_request.
*/
g_assert(qemu_mutex_iothread_locked());
arm_call_el_change_hook(cpu);
if (!kvm_enabled()) {

43
target/arm/op_helper.c
View File

@ -18,6 +18,7 @@
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "qemu/main-loop.h"
#include "cpu.h"
#include "exec/helper-proto.h"
#include "internals.h"
@ -487,7 +488,9 @@ void HELPER(cpsr_write_eret)(CPUARMState *env, uint32_t val)
*/
env->regs[15] &= (env->thumb ? ~1 : ~3);
qemu_mutex_lock_iothread();
arm_call_el_change_hook(arm_env_get_cpu(env));
qemu_mutex_unlock_iothread();
}
/* Access to user mode registers from privileged modes. */
@ -735,28 +738,58 @@ void HELPER(set_cp_reg)(CPUARMState *env, void *rip, uint32_t value)
{
const ARMCPRegInfo *ri = rip;
ri->writefn(env, ri, value);
if (ri->type & ARM_CP_IO) {
qemu_mutex_lock_iothread();
ri->writefn(env, ri, value);
qemu_mutex_unlock_iothread();
} else {
ri->writefn(env, ri, value);
}
}
uint32_t HELPER(get_cp_reg)(CPUARMState *env, void *rip)
{
const ARMCPRegInfo *ri = rip;
uint32_t res;
return ri->readfn(env, ri);
if (ri->type & ARM_CP_IO) {
qemu_mutex_lock_iothread();
res = ri->readfn(env, ri);
qemu_mutex_unlock_iothread();
} else {
res = ri->readfn(env, ri);
}
return res;
}
void HELPER(set_cp_reg64)(CPUARMState *env, void *rip, uint64_t value)
{
const ARMCPRegInfo *ri = rip;
ri->writefn(env, ri, value);
if (ri->type & ARM_CP_IO) {
qemu_mutex_lock_iothread();
ri->writefn(env, ri, value);
qemu_mutex_unlock_iothread();
} else {
ri->writefn(env, ri, value);
}
}
uint64_t HELPER(get_cp_reg64)(CPUARMState *env, void *rip)
{
const ARMCPRegInfo *ri = rip;
uint64_t res;
return ri->readfn(env, ri);
if (ri->type & ARM_CP_IO) {
qemu_mutex_lock_iothread();
res = ri->readfn(env, ri);
qemu_mutex_unlock_iothread();
} else {
res = ri->readfn(env, ri);
}
return res;
}
void HELPER(msr_i_pstate)(CPUARMState *env, uint32_t op, uint32_t imm)
@ -989,7 +1022,9 @@ void HELPER(exception_return)(CPUARMState *env)
cur_el, new_el, env->pc);
}
qemu_mutex_lock_iothread();
arm_call_el_change_hook(arm_env_get_cpu(env));
qemu_mutex_unlock_iothread();
return;

7
target/i386/smm_helper.c
View File

@ -18,6 +18,7 @@
*/
#include "qemu/osdep.h"
#include "qemu/main-loop.h"
#include "cpu.h"
#include "exec/helper-proto.h"
#include "exec/log.h"
@ -42,11 +43,14 @@ void helper_rsm(CPUX86State *env)
#define SMM_REVISION_ID 0x00020000
#endif
/* Called with iothread lock taken */
void cpu_smm_update(X86CPU *cpu)
{
CPUX86State *env = &cpu->env;
bool smm_enabled = (env->hflags & HF_SMM_MASK);
g_assert(qemu_mutex_iothread_locked());
if (cpu->smram) {
memory_region_set_enabled(cpu->smram, smm_enabled);
}
@ -333,7 +337,10 @@ void helper_rsm(CPUX86State *env)
}
env->hflags2 &= ~HF2_SMM_INSIDE_NMI_MASK;
env->hflags &= ~HF_SMM_MASK;
qemu_mutex_lock_iothread();
cpu_smm_update(cpu);
qemu_mutex_unlock_iothread();
qemu_log_mask(CPU_LOG_INT, "SMM: after RSM\n");
log_cpu_state_mask(CPU_LOG_INT, CPU(cpu), CPU_DUMP_CCOP);

5
target/s390x/misc_helper.c
View File

@ -25,6 +25,7 @@
#include "exec/helper-proto.h"
#include "sysemu/kvm.h"
#include "qemu/timer.h"
#include "qemu/main-loop.h"
#include "exec/address-spaces.h"
#ifdef CONFIG_KVM
#include <linux/kvm.h>
@ -109,11 +110,13 @@ void program_interrupt(CPUS390XState *env, uint32_t code, int ilen)
/* SCLP service call */
uint32_t HELPER(servc)(CPUS390XState *env, uint64_t r1, uint64_t r2)
{
qemu_mutex_lock_iothread();
int r = sclp_service_call(env, r1, r2);
if (r < 0) {
program_interrupt(env, -r, 4);
return 0;
r = 0;
}
qemu_mutex_unlock_iothread();
return r;
}

9
translate-all.c
View File

@ -55,6 +55,7 @@
#include "translate-all.h"
#include "qemu/bitmap.h"
#include "qemu/timer.h"
#include "qemu/main-loop.h"
#include "exec/log.h"
/* #define DEBUG_TB_INVALIDATE */
@ -1523,7 +1524,7 @@ void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t end,
#ifdef CONFIG_SOFTMMU
/* len must be <= 8 and start must be a multiple of len.
* Called via softmmu_template.h when code areas are written to with
* tb_lock held.
* iothread mutex not held.
*/
void tb_invalidate_phys_page_fast(tb_page_addr_t start, int len)
{
@ -1725,7 +1726,10 @@ void tb_check_watchpoint(CPUState *cpu)
#ifndef CONFIG_USER_ONLY
/* in deterministic execution mode, instructions doing device I/Os
must be at the end of the TB */
* must be at the end of the TB.
*
* Called by softmmu_template.h, with iothread mutex not held.
*/
void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr)
{
#if defined(TARGET_MIPS) || defined(TARGET_SH4)
@ -1937,6 +1941,7 @@ void dump_opcount_info(FILE *f, fprintf_function cpu_fprintf)
void cpu_interrupt(CPUState *cpu, int mask)
{
g_assert(qemu_mutex_iothread_locked());
cpu->interrupt_request |= mask;
cpu->tcg_exit_req = 1;
}

21
translate-common.c
View File

@ -21,6 +21,7 @@
#include "qemu-common.h"
#include "qom/cpu.h"
#include "sysemu/cpus.h"
#include "qemu/main-loop.h"
uintptr_t qemu_real_host_page_size;
intptr_t qemu_real_host_page_mask;
@ -30,6 +31,7 @@ intptr_t qemu_real_host_page_mask;
static void tcg_handle_interrupt(CPUState *cpu, int mask)
{
int old_mask;
g_assert(qemu_mutex_iothread_locked());
old_mask = cpu->interrupt_request;
cpu->interrupt_request |= mask;
@ -40,17 +42,16 @@ static void tcg_handle_interrupt(CPUState *cpu, int mask)
*/
if (!qemu_cpu_is_self(cpu)) {
qemu_cpu_kick(cpu);
return;
}
if (use_icount) {
cpu->icount_decr.u16.high = 0xffff;
if (!cpu->can_do_io
&& (mask & ~old_mask) != 0) {
cpu_abort(cpu, "Raised interrupt while not in I/O function");
}
} else {
cpu->tcg_exit_req = 1;
if (use_icount) {
cpu->icount_decr.u16.high = 0xffff;
if (!cpu->can_do_io
&& (mask & ~old_mask) != 0) {
cpu_abort(cpu, "Raised interrupt while not in I/O function");
}
} else {
cpu->tcg_exit_req = 1;
}
}
}