| Message ID | 20221111154758.1372674-2-eesposit@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: allow listener to stop all vcpus before | expand |
On 11/11/22 16:47, Emanuele Giuseppe Esposito wrote: > This API allows the accelerators to prevent vcpus from issuing > new ioctls while execting a critical section marked with the > accel_ioctl_inhibit_begin/end functions. > > Note that all functions submitting ioctls must mark where the > ioctl is being called with accel_{cpu_}ioctl_begin/end(). > > This API requires the caller to always hold the BQL. > API documentation is in sysemu/accel-blocker.h > > Internally, it uses a QemuLockCnt together with a per-CPU QemuLockCnt > (to minimize cache line bouncing) to keep avoid that new ioctls > run when the critical section starts, and a QemuEvent to wait > that all running ioctls finish. > > Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> > --- > accel/accel-blocker.c | 154 +++++++++++++++++++++++++++++++++ > accel/meson.build | 2 +- > hw/core/cpu-common.c | 2 + > include/hw/core/cpu.h | 3 + > include/sysemu/accel-blocker.h | 56 ++++++++++++ > 5 files changed, 216 insertions(+), 1 deletion(-) > create mode 100644 accel/accel-blocker.c > create mode 100644 include/sysemu/accel-blocker.h Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
On 18/11/22 08:32, Philippe Mathieu-Daudé wrote: > On 11/11/22 16:47, Emanuele Giuseppe Esposito wrote: >> This API allows the accelerators to prevent vcpus from issuing >> new ioctls while execting a critical section marked with the Typo "executing". >> accel_ioctl_inhibit_begin/end functions. >> >> Note that all functions submitting ioctls must mark where the >> ioctl is being called with accel_{cpu_}ioctl_begin/end(). >> >> This API requires the caller to always hold the BQL. >> API documentation is in sysemu/accel-blocker.h >> >> Internally, it uses a QemuLockCnt together with a per-CPU QemuLockCnt >> (to minimize cache line bouncing) to keep avoid that new ioctls >> run when the critical section starts, and a QemuEvent to wait >> that all running ioctls finish. >> >> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> >> --- >> accel/accel-blocker.c | 154 +++++++++++++++++++++++++++++++++ >> accel/meson.build | 2 +- >> hw/core/cpu-common.c | 2 + >> include/hw/core/cpu.h | 3 + >> include/sysemu/accel-blocker.h | 56 ++++++++++++ >> 5 files changed, 216 insertions(+), 1 deletion(-) >> create mode 100644 accel/accel-blocker.c >> create mode 100644 include/sysemu/accel-blocker.h > > Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> >
On Fri, 2022-11-11 at 10:47 -0500, Emanuele Giuseppe Esposito wrote: > This API allows the accelerators to prevent vcpus from issuing > new ioctls while execting a critical section marked with the > accel_ioctl_inhibit_begin/end functions. > > Note that all functions submitting ioctls must mark where the > ioctl is being called with accel_{cpu_}ioctl_begin/end(). > > This API requires the caller to always hold the BQL. > API documentation is in sysemu/accel-blocker.h > > Internally, it uses a QemuLockCnt together with a per-CPU QemuLockCnt > (to minimize cache line bouncing) to keep avoid that new ioctls > run when the critical section starts, and a QemuEvent to wait > that all running ioctls finish. > > Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> > --- > accel/accel-blocker.c | 154 > +++++++++++++++++++++++++++++++++ > accel/meson.build | 2 +- > hw/core/cpu-common.c | 2 + > include/hw/core/cpu.h | 3 + > include/sysemu/accel-blocker.h | 56 ++++++++++++ > 5 files changed, 216 insertions(+), 1 deletion(-) > create mode 100644 accel/accel-blocker.c > create mode 100644 include/sysemu/accel-blocker.h > > diff --git a/accel/accel-blocker.c b/accel/accel-blocker.c > new file mode 100644 > index 0000000000..1e7f423462 > --- /dev/null > +++ b/accel/accel-blocker.c > @@ -0,0 +1,154 @@ > +/* > + * Lock to inhibit accelerator ioctls > + * > + * Copyright (c) 2022 Red Hat Inc. > + * > + * Author: Emanuele Giuseppe Esposito <eesposit@redhat.com> > + * > + * Permission is hereby granted, free of charge, to any person > obtaining a copy > + * of this software and associated documentation files (the > "Software"), to deal > + * in the Software without restriction, including without limitation > the rights > + * to use, copy, modify, merge, publish, distribute, sublicense, > and/or sell > + * copies of the Software, and to permit persons to whom the > Software is > + * furnished to do so, subject to the following conditions: > + * > + * The above copyright notice and this permission notice shall be > included in > + * all copies or substantial portions of the Software. > + * > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, > EXPRESS OR > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF > MERCHANTABILITY, > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT > SHALL > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES > OR OTHER > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, > ARISING FROM, > + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER > DEALINGS IN > + * THE SOFTWARE. > + */ > + > +#include "qemu/osdep.h" > +#include "qemu/thread.h" > +#include "qemu/main-loop.h" > +#include "hw/core/cpu.h" > +#include "sysemu/accel-blocker.h" > + > +static QemuLockCnt accel_in_ioctl_lock; > +static QemuEvent accel_in_ioctl_event; > + > +void accel_blocker_init(void) > +{ > + qemu_lockcnt_init(&accel_in_ioctl_lock); > + qemu_event_init(&accel_in_ioctl_event, false); > +} > + > +void accel_ioctl_begin(void) > +{ > + if (likely(qemu_mutex_iothread_locked())) { > + return; > + } > + > + /* block if lock is taken in kvm_ioctl_inhibit_begin() */ > + qemu_lockcnt_inc(&accel_in_ioctl_lock); > +} > + > +void accel_ioctl_end(void) > +{ > + if (likely(qemu_mutex_iothread_locked())) { > + return; > + } > + > + qemu_lockcnt_dec(&accel_in_ioctl_lock); > + /* change event to SET. If event was BUSY, wake up all waiters > */ > + qemu_event_set(&accel_in_ioctl_event); > +} > + > +void accel_cpu_ioctl_begin(CPUState *cpu) > +{ > + if (unlikely(qemu_mutex_iothread_locked())) { > + return; > + } > + > + /* block if lock is taken in kvm_ioctl_inhibit_begin() */ > + qemu_lockcnt_inc(&cpu->in_ioctl_lock); > +} > + > +void accel_cpu_ioctl_end(CPUState *cpu) > +{ > + if (unlikely(qemu_mutex_iothread_locked())) { > + return; > + } > + > + qemu_lockcnt_dec(&cpu->in_ioctl_lock); > + /* change event to SET. If event was BUSY, wake up all waiters > */ > + qemu_event_set(&accel_in_ioctl_event); > +} > + > +static bool accel_has_to_wait(void) > +{ > + CPUState *cpu; > + bool needs_to_wait = false; > + > + CPU_FOREACH(cpu) { > + if (qemu_lockcnt_count(&cpu->in_ioctl_lock)) { > + /* exit the ioctl, if vcpu is running it */ > + qemu_cpu_kick(cpu); > + needs_to_wait = true; > + } > + } > + > + return needs_to_wait || > qemu_lockcnt_count(&accel_in_ioctl_lock); > +} > + > +void accel_ioctl_inhibit_begin(void) > +{ > + CPUState *cpu; > + > + /* > + * We allow to inhibit only when holding the BQL, so we can > identify > + * when an inhibitor wants to issue an ioctl easily. > + */ > + g_assert(qemu_mutex_iothread_locked()); > + > + /* Block further invocations of the ioctls outside the BQL. */ > + CPU_FOREACH(cpu) { > + qemu_lockcnt_lock(&cpu->in_ioctl_lock); > + } > + qemu_lockcnt_lock(&accel_in_ioctl_lock); > + > + /* Keep waiting until there are running ioctls */ > + while (true) { > + > + /* Reset event to FREE. */ > + qemu_event_reset(&accel_in_ioctl_event); > + > + if (accel_has_to_wait()) { > + /* > + * If event is still FREE, and there are ioctls still in > progress, > + * wait. > + * > + * If an ioctl finishes before qemu_event_wait(), it > will change > + * the event state to SET. This will prevent > qemu_event_wait() from > + * blocking, but it's not a problem because if other > ioctls are > + * still running the loop will iterate once more and > reset the event > + * status to FREE so that it can wait properly. > + * > + * If an ioctls finishes while qemu_event_wait() is > blocking, then > + * it will be waken up, but also here the while loop > makes sure > + * to re-enter the wait if there are other running > ioctls. > + */ > + qemu_event_wait(&accel_in_ioctl_event); > + } else { > + /* No ioctl is running */ > + return; > + } > + } > +} > + > +void accel_ioctl_inhibit_end(void) > +{ > + CPUState *cpu; > + > + qemu_lockcnt_unlock(&accel_in_ioctl_lock); > + CPU_FOREACH(cpu) { > + qemu_lockcnt_unlock(&cpu->in_ioctl_lock); > + } > +} > + > diff --git a/accel/meson.build b/accel/meson.build > index b9a963cf80..a0d49c4f31 100644 > --- a/accel/meson.build > +++ b/accel/meson.build > @@ -1,4 +1,4 @@ > -specific_ss.add(files('accel-common.c')) > +specific_ss.add(files('accel-common.c', 'accel-blocker.c')) > softmmu_ss.add(files('accel-softmmu.c')) > user_ss.add(files('accel-user.c')) > > diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c > index f9fdd46b9d..8d6a4b1b65 100644 > --- a/hw/core/cpu-common.c > +++ b/hw/core/cpu-common.c > @@ -237,6 +237,7 @@ static void cpu_common_initfn(Object *obj) > cpu->nr_threads = 1; > > qemu_mutex_init(&cpu->work_mutex); > + qemu_lockcnt_init(&cpu->in_ioctl_lock); > QSIMPLEQ_INIT(&cpu->work_list); > QTAILQ_INIT(&cpu->breakpoints); > QTAILQ_INIT(&cpu->watchpoints); > @@ -248,6 +249,7 @@ static void cpu_common_finalize(Object *obj) > { > CPUState *cpu = CPU(obj); > > + qemu_lockcnt_destroy(&cpu->in_ioctl_lock); > qemu_mutex_destroy(&cpu->work_mutex); > } > > diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h > index f9b58773f7..15053663bc 100644 > --- a/include/hw/core/cpu.h > +++ b/include/hw/core/cpu.h > @@ -397,6 +397,9 @@ struct CPUState { > uint32_t kvm_fetch_index; > uint64_t dirty_pages; > > + /* Use by accel-block: CPU is executing an ioctl() */ > + QemuLockCnt in_ioctl_lock; > + > /* Used for events with 'vcpu' and *without* the 'disabled' > properties */ > DECLARE_BITMAP(trace_dstate_delayed, > CPU_TRACE_DSTATE_MAX_EVENTS); > DECLARE_BITMAP(trace_dstate, CPU_TRACE_DSTATE_MAX_EVENTS); > diff --git a/include/sysemu/accel-blocker.h b/include/sysemu/accel- > blocker.h > new file mode 100644 > index 0000000000..72020529ef > --- /dev/null > +++ b/include/sysemu/accel-blocker.h > @@ -0,0 +1,56 @@ > +/* > + * Accelerator blocking API, to prevent new ioctls from starting and > wait the > + * running ones finish. > + * This mechanism differs from pause/resume_all_vcpus() in that it > does not > + * release the BQL. > + * > + * Copyright (c) 2022 Red Hat Inc. > + * > + * Author: Emanuele Giuseppe Esposito <eesposit@redhat.com> > + * > + * This work is licensed under the terms of the GNU GPL, version 2 > or later. > + * See the COPYING file in the top-level directory. > + */ > +#ifndef ACCEL_BLOCKER_H > +#define ACCEL_BLOCKER_H > + > +#include "qemu/osdep.h" > +#include "sysemu/cpus.h" > + > +extern void accel_blocker_init(void); > + > +/* > + * accel_{cpu_}ioctl_begin/end: > + * Mark when ioctl is about to run or just finished. > + * > + * accel_{cpu_}ioctl_begin will block after > accel_ioctl_inhibit_begin() is > + * called, preventing new ioctls to run. They will continue only > after > + * accel_ioctl_inibith_end(). Typo inibith --> inhibit > + */ > +extern void accel_ioctl_begin(void); > +extern void accel_ioctl_end(void); > +extern void accel_cpu_ioctl_begin(CPUState *cpu); > +extern void accel_cpu_ioctl_end(CPUState *cpu); > + > +/* > + * accel_ioctl_inhibit_begin: start critical section > + * > + * This function makes sure that: > + * 1) incoming accel_{cpu_}ioctl_begin() calls block > + * 2) wait that all ioctls that were already running reach > + * accel_{cpu_}ioctl_end(), kicking vcpus if necessary. > + * > + * This allows the caller to access shared data or perform > operations without > + * worrying of concurrent vcpus accesses. > + */ > +extern void accel_ioctl_inhibit_begin(void); > + > +/* > + * accel_ioctl_inhibit_end: end critical section started by > + * accel_ioctl_inhibit_begin() > + * > + * This function allows blocked accel_{cpu_}ioctl_begin() to > continue. > + */ > +extern void accel_ioctl_inhibit_end(void); > + git am complains ".git/rebase-apply/patch:170: new blank line at EOF." > +#endif /* ACCEL_BLOCKER_H */
diff --git a/accel/accel-blocker.c b/accel/accel-blocker.c new file mode 100644 index 0000000000..1e7f423462 --- /dev/null +++ b/accel/accel-blocker.c @@ -0,0 +1,154 @@ +/* + * Lock to inhibit accelerator ioctls + * + * Copyright (c) 2022 Red Hat Inc. + * + * Author: Emanuele Giuseppe Esposito <eesposit@redhat.com> + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "qemu/osdep.h" +#include "qemu/thread.h" +#include "qemu/main-loop.h" +#include "hw/core/cpu.h" +#include "sysemu/accel-blocker.h" + +static QemuLockCnt accel_in_ioctl_lock; +static QemuEvent accel_in_ioctl_event; + +void accel_blocker_init(void) +{ + qemu_lockcnt_init(&accel_in_ioctl_lock); + qemu_event_init(&accel_in_ioctl_event, false); +} + +void accel_ioctl_begin(void) +{ + if (likely(qemu_mutex_iothread_locked())) { + return; + } + + /* block if lock is taken in kvm_ioctl_inhibit_begin() */ + qemu_lockcnt_inc(&accel_in_ioctl_lock); +} + +void accel_ioctl_end(void) +{ + if (likely(qemu_mutex_iothread_locked())) { + return; + } + + qemu_lockcnt_dec(&accel_in_ioctl_lock); + /* change event to SET. If event was BUSY, wake up all waiters */ + qemu_event_set(&accel_in_ioctl_event); +} + +void accel_cpu_ioctl_begin(CPUState *cpu) +{ + if (unlikely(qemu_mutex_iothread_locked())) { + return; + } + + /* block if lock is taken in kvm_ioctl_inhibit_begin() */ + qemu_lockcnt_inc(&cpu->in_ioctl_lock); +} + +void accel_cpu_ioctl_end(CPUState *cpu) +{ + if (unlikely(qemu_mutex_iothread_locked())) { + return; + } + + qemu_lockcnt_dec(&cpu->in_ioctl_lock); + /* change event to SET. If event was BUSY, wake up all waiters */ + qemu_event_set(&accel_in_ioctl_event); +} + +static bool accel_has_to_wait(void) +{ + CPUState *cpu; + bool needs_to_wait = false; + + CPU_FOREACH(cpu) { + if (qemu_lockcnt_count(&cpu->in_ioctl_lock)) { + /* exit the ioctl, if vcpu is running it */ + qemu_cpu_kick(cpu); + needs_to_wait = true; + } + } + + return needs_to_wait || qemu_lockcnt_count(&accel_in_ioctl_lock); +} + +void accel_ioctl_inhibit_begin(void) +{ + CPUState *cpu; + + /* + * We allow to inhibit only when holding the BQL, so we can identify + * when an inhibitor wants to issue an ioctl easily. + */ + g_assert(qemu_mutex_iothread_locked()); + + /* Block further invocations of the ioctls outside the BQL. */ + CPU_FOREACH(cpu) { + qemu_lockcnt_lock(&cpu->in_ioctl_lock); + } + qemu_lockcnt_lock(&accel_in_ioctl_lock); + + /* Keep waiting until there are running ioctls */ + while (true) { + + /* Reset event to FREE. */ + qemu_event_reset(&accel_in_ioctl_event); + + if (accel_has_to_wait()) { + /* + * If event is still FREE, and there are ioctls still in progress, + * wait. + * + * If an ioctl finishes before qemu_event_wait(), it will change + * the event state to SET. This will prevent qemu_event_wait() from + * blocking, but it's not a problem because if other ioctls are + * still running the loop will iterate once more and reset the event + * status to FREE so that it can wait properly. + * + * If an ioctls finishes while qemu_event_wait() is blocking, then + * it will be waken up, but also here the while loop makes sure + * to re-enter the wait if there are other running ioctls. + */ + qemu_event_wait(&accel_in_ioctl_event); + } else { + /* No ioctl is running */ + return; + } + } +} + +void accel_ioctl_inhibit_end(void) +{ + CPUState *cpu; + + qemu_lockcnt_unlock(&accel_in_ioctl_lock); + CPU_FOREACH(cpu) { + qemu_lockcnt_unlock(&cpu->in_ioctl_lock); + } +} + diff --git a/accel/meson.build b/accel/meson.build index b9a963cf80..a0d49c4f31 100644 --- a/accel/meson.build +++ b/accel/meson.build @@ -1,4 +1,4 @@ -specific_ss.add(files('accel-common.c')) +specific_ss.add(files('accel-common.c', 'accel-blocker.c')) softmmu_ss.add(files('accel-softmmu.c')) user_ss.add(files('accel-user.c')) diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c index f9fdd46b9d..8d6a4b1b65 100644 --- a/hw/core/cpu-common.c +++ b/hw/core/cpu-common.c @@ -237,6 +237,7 @@ static void cpu_common_initfn(Object *obj) cpu->nr_threads = 1; qemu_mutex_init(&cpu->work_mutex); + qemu_lockcnt_init(&cpu->in_ioctl_lock); QSIMPLEQ_INIT(&cpu->work_list); QTAILQ_INIT(&cpu->breakpoints); QTAILQ_INIT(&cpu->watchpoints); @@ -248,6 +249,7 @@ static void cpu_common_finalize(Object *obj) { CPUState *cpu = CPU(obj); + qemu_lockcnt_destroy(&cpu->in_ioctl_lock); qemu_mutex_destroy(&cpu->work_mutex); } diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h index f9b58773f7..15053663bc 100644 --- a/include/hw/core/cpu.h +++ b/include/hw/core/cpu.h @@ -397,6 +397,9 @@ struct CPUState { uint32_t kvm_fetch_index; uint64_t dirty_pages; + /* Use by accel-block: CPU is executing an ioctl() */ + QemuLockCnt in_ioctl_lock; + /* Used for events with 'vcpu' and *without* the 'disabled' properties */ DECLARE_BITMAP(trace_dstate_delayed, CPU_TRACE_DSTATE_MAX_EVENTS); DECLARE_BITMAP(trace_dstate, CPU_TRACE_DSTATE_MAX_EVENTS); diff --git a/include/sysemu/accel-blocker.h b/include/sysemu/accel-blocker.h new file mode 100644 index 0000000000..72020529ef --- /dev/null +++ b/include/sysemu/accel-blocker.h @@ -0,0 +1,56 @@ +/* + * Accelerator blocking API, to prevent new ioctls from starting and wait the + * running ones finish. + * This mechanism differs from pause/resume_all_vcpus() in that it does not + * release the BQL. + * + * Copyright (c) 2022 Red Hat Inc. + * + * Author: Emanuele Giuseppe Esposito <eesposit@redhat.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ +#ifndef ACCEL_BLOCKER_H +#define ACCEL_BLOCKER_H + +#include "qemu/osdep.h" +#include "sysemu/cpus.h" + +extern void accel_blocker_init(void); + +/* + * accel_{cpu_}ioctl_begin/end: + * Mark when ioctl is about to run or just finished. + * + * accel_{cpu_}ioctl_begin will block after accel_ioctl_inhibit_begin() is + * called, preventing new ioctls to run. They will continue only after + * accel_ioctl_inibith_end(). + */ +extern void accel_ioctl_begin(void); +extern void accel_ioctl_end(void); +extern void accel_cpu_ioctl_begin(CPUState *cpu); +extern void accel_cpu_ioctl_end(CPUState *cpu); + +/* + * accel_ioctl_inhibit_begin: start critical section + * + * This function makes sure that: + * 1) incoming accel_{cpu_}ioctl_begin() calls block + * 2) wait that all ioctls that were already running reach + * accel_{cpu_}ioctl_end(), kicking vcpus if necessary. + * + * This allows the caller to access shared data or perform operations without + * worrying of concurrent vcpus accesses. + */ +extern void accel_ioctl_inhibit_begin(void); + +/* + * accel_ioctl_inhibit_end: end critical section started by + * accel_ioctl_inhibit_begin() + * + * This function allows blocked accel_{cpu_}ioctl_begin() to continue. + */ +extern void accel_ioctl_inhibit_end(void); + +#endif /* ACCEL_BLOCKER_H */
This API allows the accelerators to prevent vcpus from issuing new ioctls while execting a critical section marked with the accel_ioctl_inhibit_begin/end functions. Note that all functions submitting ioctls must mark where the ioctl is being called with accel_{cpu_}ioctl_begin/end(). This API requires the caller to always hold the BQL. API documentation is in sysemu/accel-blocker.h Internally, it uses a QemuLockCnt together with a per-CPU QemuLockCnt (to minimize cache line bouncing) to keep avoid that new ioctls run when the critical section starts, and a QemuEvent to wait that all running ioctls finish. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> --- accel/accel-blocker.c | 154 +++++++++++++++++++++++++++++++++ accel/meson.build | 2 +- hw/core/cpu-common.c | 2 + include/hw/core/cpu.h | 3 + include/sysemu/accel-blocker.h | 56 ++++++++++++ 5 files changed, 216 insertions(+), 1 deletion(-) create mode 100644 accel/accel-blocker.c create mode 100644 include/sysemu/accel-blocker.h