diff mbox series

[v5,02/14] cpus: prepare new CpusAccel cpu accelerator interface

Message ID 20200812183250.9221-3-cfontana@suse.de
State New
Headers show
Series QEMU cpus.c refactoring part2 | expand

Commit Message

Claudio Fontana Aug. 12, 2020, 6:32 p.m. UTC
The new interface starts unused, will start being used by the
next patches.

It provides methods for each accelerator to start a vcpu, kick a vcpu,
synchronize state, get cpu virtual clock and elapsed ticks.

In qemu_wait_io_event, make it clear that APC is used only for HAX
on Windows.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
---
 hw/core/cpu.c                  |   1 +
 hw/i386/x86.c                  |   2 +-
 include/sysemu/cpu-timers.h    |   9 +-
 include/sysemu/cpus.h          |  36 ++++++++
 include/sysemu/hw_accel.h      |  69 ++-------------
 softmmu/cpu-timers.c           |   9 +-
 softmmu/cpus.c                 | 195 ++++++++++++++++++++++++++++++++---------
 stubs/Makefile.objs            |   2 +
 stubs/cpu-synchronize-state.c  |  15 ++++
 stubs/cpus-get-virtual-clock.c |   8 ++
 util/qemu-timer.c              |   8 +-
 11 files changed, 231 insertions(+), 123 deletions(-)
 create mode 100644 stubs/cpu-synchronize-state.c
 create mode 100644 stubs/cpus-get-virtual-clock.c

Comments

Richard Henderson Aug. 14, 2020, 8:28 p.m. UTC | #1
On 8/12/20 11:32 AM, Claudio Fontana wrote:
>  uint64_t cpu_get_tsc(CPUX86State *env)
>  {
> -    return cpu_get_ticks();
> +    return cpus_get_elapsed_ticks();

What has this change got to do with creating the interface?
You said the interface wasn't used yet...


> diff --git a/stubs/cpu-synchronize-state.c b/stubs/cpu-synchronize-state.c
> new file mode 100644
> index 0000000000..3112fe439d
> --- /dev/null
> +++ b/stubs/cpu-synchronize-state.c
> @@ -0,0 +1,15 @@
> +#include "qemu/osdep.h"
> +#include "sysemu/hw_accel.h"
> +
> +void cpu_synchronize_state(CPUState *cpu)
> +{
> +}
> +void cpu_synchronize_post_reset(CPUState *cpu)
> +{
> +}
> +void cpu_synchronize_post_init(CPUState *cpu)
> +{
> +}
> +void cpu_synchronize_pre_loadvm(CPUState *cpu)
> +{
> +}
> diff --git a/stubs/cpus-get-virtual-clock.c b/stubs/cpus-get-virtual-clock.c
> new file mode 100644
> index 0000000000..fd447d53f3
> --- /dev/null
> +++ b/stubs/cpus-get-virtual-clock.c
> @@ -0,0 +1,8 @@
> +#include "qemu/osdep.h"
> +#include "sysemu/cpu-timers.h"
> +#include "qemu/main-loop.h"
> +
> +int64_t cpus_get_virtual_clock(void)
> +{
> +    return cpu_get_clock();
> +}

How do these stubs get used?


r~
Claudio Fontana Aug. 19, 2020, 1:49 p.m. UTC | #2
Hello Richard,

On 8/14/20 10:28 PM, Richard Henderson wrote:
> On 8/12/20 11:32 AM, Claudio Fontana wrote:
>>  uint64_t cpu_get_tsc(CPUX86State *env)
>>  {
>> -    return cpu_get_ticks();
>> +    return cpus_get_elapsed_ticks();
> 
> What has this change got to do with creating the interface?
> You said the interface wasn't used yet...

the new CpusAccel interface isn't used,

The cpu_get_ticks() function is changed to mean getting the actual cpu ticks,
while cpus_get_elapsed_ticks() contains the code that special cases icount and qtest,
until the respective CpusAccel enablement patches.

> 
> 
>> diff --git a/stubs/cpu-synchronize-state.c b/stubs/cpu-synchronize-state.c
>> new file mode 100644
>> index 0000000000..3112fe439d
>> --- /dev/null
>> +++ b/stubs/cpu-synchronize-state.c
>> @@ -0,0 +1,15 @@
>> +#include "qemu/osdep.h"
>> +#include "sysemu/hw_accel.h"
>> +
>> +void cpu_synchronize_state(CPUState *cpu)
>> +{
>> +}
>> +void cpu_synchronize_post_reset(CPUState *cpu)
>> +{
>> +}
>> +void cpu_synchronize_post_init(CPUState *cpu)
>> +{
>> +}
>> +void cpu_synchronize_pre_loadvm(CPUState *cpu)
>> +{
>> +}


these are needed for non softmmu builds by hw/core/cpu.c
and by gdbstub.c,
but actually we could get away with just _state() and _post_init(). Will remove the others.


>> diff --git a/stubs/cpus-get-virtual-clock.c b/stubs/cpus-get-virtual-clock.c
>> new file mode 100644
>> index 0000000000..fd447d53f3
>> --- /dev/null
>> +++ b/stubs/cpus-get-virtual-clock.c
>> @@ -0,0 +1,8 @@
>> +#include "qemu/osdep.h"
>> +#include "sysemu/cpu-timers.h"
>> +#include "qemu/main-loop.h"
>> +
>> +int64_t cpus_get_virtual_clock(void)
>> +{
>> +    return cpu_get_clock();
>> +}
> 
> How do these stubs get used?
> 
> 
> r~
> 

util/timer.c needs it for non-softmmu builds (see previous discussion with Paolo).

Thanks,

Claudio
diff mbox series

Patch

diff --git a/hw/core/cpu.c b/hw/core/cpu.c
index 594441a150..b389a312df 100644
--- a/hw/core/cpu.c
+++ b/hw/core/cpu.c
@@ -33,6 +33,7 @@ 
 #include "hw/qdev-properties.h"
 #include "trace-root.h"
 #include "qemu/plugin.h"
+#include "sysemu/hw_accel.h"
 
 CPUInterruptHandler cpu_interrupt_handler;
 
diff --git a/hw/i386/x86.c b/hw/i386/x86.c
index 58cf2229d5..00c35bad7e 100644
--- a/hw/i386/x86.c
+++ b/hw/i386/x86.c
@@ -264,7 +264,7 @@  static long get_file_size(FILE *f)
 /* TSC handling */
 uint64_t cpu_get_tsc(CPUX86State *env)
 {
-    return cpu_get_ticks();
+    return cpus_get_elapsed_ticks();
 }
 
 /* IRQ handling */
diff --git a/include/sysemu/cpu-timers.h b/include/sysemu/cpu-timers.h
index 07d724672f..cb83cc5584 100644
--- a/include/sysemu/cpu-timers.h
+++ b/include/sysemu/cpu-timers.h
@@ -64,9 +64,8 @@  void cpu_enable_ticks(void);
 void cpu_disable_ticks(void);
 
 /*
- * return the time elapsed in VM between vm_start and vm_stop.  Unless
- * icount is active, cpu_get_ticks() uses units of the host CPU cycle
- * counter.
+ * return the time elapsed in VM between vm_start and vm_stop.
+ * cpu_get_ticks() uses units of the host CPU cycle counter.
  */
 int64_t cpu_get_ticks(void);
 
@@ -78,4 +77,8 @@  int64_t cpu_get_clock(void);
 
 void qemu_timer_notify_cb(void *opaque, QEMUClockType type);
 
+/* get the VIRTUAL clock and VM elapsed ticks via the cpus accel interface */
+int64_t cpus_get_virtual_clock(void);
+int64_t cpus_get_elapsed_ticks(void);
+
 #endif /* SYSEMU_CPU_TIMERS_H */
diff --git a/include/sysemu/cpus.h b/include/sysemu/cpus.h
index 149de000a0..db196dd96f 100644
--- a/include/sysemu/cpus.h
+++ b/include/sysemu/cpus.h
@@ -4,7 +4,43 @@ 
 #include "qemu/timer.h"
 
 /* cpus.c */
+
+/* CPU execution threads */
+
+typedef struct CpusAccel {
+    void (*create_vcpu_thread)(CPUState *cpu); /* MANDATORY */
+    void (*kick_vcpu_thread)(CPUState *cpu);
+
+    void (*synchronize_post_reset)(CPUState *cpu);
+    void (*synchronize_post_init)(CPUState *cpu);
+    void (*synchronize_state)(CPUState *cpu);
+    void (*synchronize_pre_loadvm)(CPUState *cpu);
+
+    int64_t (*get_virtual_clock)(void);
+    int64_t (*get_elapsed_ticks)(void);
+} CpusAccel;
+
+/* register accel-specific cpus interface implementation */
+void cpus_register_accel(CpusAccel *i);
+
+/* interface available for cpus accelerator threads */
+
+/* For temporary buffers for forming a name */
+#define VCPU_THREAD_NAME_SIZE 16
+
+void cpus_kick_thread(CPUState *cpu);
+bool cpu_work_list_empty(CPUState *cpu);
+bool cpu_thread_is_idle(CPUState *cpu);
 bool all_cpu_threads_idle(void);
+bool cpu_can_run(CPUState *cpu);
+void qemu_wait_io_event_common(CPUState *cpu);
+void qemu_wait_io_event(CPUState *cpu);
+void cpu_thread_signal_created(CPUState *cpu);
+void cpu_thread_signal_destroyed(CPUState *cpu);
+void cpu_handle_guest_debug(CPUState *cpu);
+
+/* end interface for cpus accelerator threads */
+
 bool qemu_in_vcpu_thread(void);
 void qemu_init_cpu_loop(void);
 void resume_all_vcpus(void);
diff --git a/include/sysemu/hw_accel.h b/include/sysemu/hw_accel.h
index e128f8b06b..ffed6192a3 100644
--- a/include/sysemu/hw_accel.h
+++ b/include/sysemu/hw_accel.h
@@ -1,5 +1,5 @@ 
 /*
- * QEMU Hardware accelertors support
+ * QEMU Hardware accelerators support
  *
  * Copyright 2016 Google, Inc.
  *
@@ -17,68 +17,9 @@ 
 #include "sysemu/hvf.h"
 #include "sysemu/whpx.h"
 
-static inline void cpu_synchronize_state(CPUState *cpu)
-{
-    if (kvm_enabled()) {
-        kvm_cpu_synchronize_state(cpu);
-    }
-    if (hax_enabled()) {
-        hax_cpu_synchronize_state(cpu);
-    }
-    if (hvf_enabled()) {
-        hvf_cpu_synchronize_state(cpu);
-    }
-    if (whpx_enabled()) {
-        whpx_cpu_synchronize_state(cpu);
-    }
-}
-
-static inline void cpu_synchronize_post_reset(CPUState *cpu)
-{
-    if (kvm_enabled()) {
-        kvm_cpu_synchronize_post_reset(cpu);
-    }
-    if (hax_enabled()) {
-        hax_cpu_synchronize_post_reset(cpu);
-    }
-    if (hvf_enabled()) {
-        hvf_cpu_synchronize_post_reset(cpu);
-    }
-    if (whpx_enabled()) {
-        whpx_cpu_synchronize_post_reset(cpu);
-    }
-}
-
-static inline void cpu_synchronize_post_init(CPUState *cpu)
-{
-    if (kvm_enabled()) {
-        kvm_cpu_synchronize_post_init(cpu);
-    }
-    if (hax_enabled()) {
-        hax_cpu_synchronize_post_init(cpu);
-    }
-    if (hvf_enabled()) {
-        hvf_cpu_synchronize_post_init(cpu);
-    }
-    if (whpx_enabled()) {
-        whpx_cpu_synchronize_post_init(cpu);
-    }
-}
-
-static inline void cpu_synchronize_pre_loadvm(CPUState *cpu)
-{
-    if (kvm_enabled()) {
-        kvm_cpu_synchronize_pre_loadvm(cpu);
-    }
-    if (hax_enabled()) {
-        hax_cpu_synchronize_pre_loadvm(cpu);
-    }
-    if (hvf_enabled()) {
-        hvf_cpu_synchronize_pre_loadvm(cpu);
-    }
-    if (whpx_enabled()) {
-        whpx_cpu_synchronize_pre_loadvm(cpu);
-    }
-}
+void cpu_synchronize_state(CPUState *cpu);
+void cpu_synchronize_post_reset(CPUState *cpu);
+void cpu_synchronize_post_init(CPUState *cpu);
+void cpu_synchronize_pre_loadvm(CPUState *cpu);
 
 #endif /* QEMU_HW_ACCEL_H */
diff --git a/softmmu/cpu-timers.c b/softmmu/cpu-timers.c
index 64addb315d..3e1da79735 100644
--- a/softmmu/cpu-timers.c
+++ b/softmmu/cpu-timers.c
@@ -61,18 +61,13 @@  static int64_t cpu_get_ticks_locked(void)
 }
 
 /*
- * return the time elapsed in VM between vm_start and vm_stop.  Unless
- * icount is active, cpu_get_ticks() uses units of the host CPU cycle
- * counter.
+ * return the time elapsed in VM between vm_start and vm_stop.
+ * cpu_get_ticks() uses units of the host CPU cycle counter.
  */
 int64_t cpu_get_ticks(void)
 {
     int64_t ticks;
 
-    if (icount_enabled()) {
-        return icount_get();
-    }
-
     qemu_spin_lock(&timers_state.vm_clock_lock);
     ticks = cpu_get_ticks_locked();
     qemu_spin_unlock(&timers_state.vm_clock_lock);
diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index 54fdb2761c..2b15b5f86b 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -87,7 +87,7 @@  bool cpu_is_stopped(CPUState *cpu)
     return cpu->stopped || !runstate_is_running();
 }
 
-static inline bool cpu_work_list_empty(CPUState *cpu)
+bool cpu_work_list_empty(CPUState *cpu)
 {
     bool ret;
 
@@ -97,7 +97,7 @@  static inline bool cpu_work_list_empty(CPUState *cpu)
     return ret;
 }
 
-static bool cpu_thread_is_idle(CPUState *cpu)
+bool cpu_thread_is_idle(CPUState *cpu)
 {
     if (cpu->stop || !cpu_work_list_empty(cpu)) {
         return false;
@@ -215,6 +215,11 @@  void hw_error(const char *fmt, ...)
     abort();
 }
 
+/*
+ * The chosen accelerator is supposed to register this.
+ */
+static CpusAccel *cpus_accel;
+
 void cpu_synchronize_all_states(void)
 {
     CPUState *cpu;
@@ -251,6 +256,102 @@  void cpu_synchronize_all_pre_loadvm(void)
     }
 }
 
+void cpu_synchronize_state(CPUState *cpu)
+{
+    if (cpus_accel && cpus_accel->synchronize_state) {
+        cpus_accel->synchronize_state(cpu);
+    }
+    if (kvm_enabled()) {
+        kvm_cpu_synchronize_state(cpu);
+    }
+    if (hax_enabled()) {
+        hax_cpu_synchronize_state(cpu);
+    }
+    if (whpx_enabled()) {
+        whpx_cpu_synchronize_state(cpu);
+    }
+}
+
+void cpu_synchronize_post_reset(CPUState *cpu)
+{
+    if (cpus_accel && cpus_accel->synchronize_post_reset) {
+        cpus_accel->synchronize_post_reset(cpu);
+    }
+    if (kvm_enabled()) {
+        kvm_cpu_synchronize_post_reset(cpu);
+    }
+    if (hax_enabled()) {
+        hax_cpu_synchronize_post_reset(cpu);
+    }
+    if (whpx_enabled()) {
+        whpx_cpu_synchronize_post_reset(cpu);
+    }
+}
+
+void cpu_synchronize_post_init(CPUState *cpu)
+{
+    if (cpus_accel && cpus_accel->synchronize_post_init) {
+        cpus_accel->synchronize_post_init(cpu);
+    }
+    if (kvm_enabled()) {
+        kvm_cpu_synchronize_post_init(cpu);
+    }
+    if (hax_enabled()) {
+        hax_cpu_synchronize_post_init(cpu);
+    }
+    if (whpx_enabled()) {
+        whpx_cpu_synchronize_post_init(cpu);
+    }
+}
+
+void cpu_synchronize_pre_loadvm(CPUState *cpu)
+{
+    if (cpus_accel && cpus_accel->synchronize_pre_loadvm) {
+        cpus_accel->synchronize_pre_loadvm(cpu);
+    }
+    if (kvm_enabled()) {
+        kvm_cpu_synchronize_pre_loadvm(cpu);
+    }
+    if (hax_enabled()) {
+        hax_cpu_synchronize_pre_loadvm(cpu);
+    }
+    if (hvf_enabled()) {
+        hvf_cpu_synchronize_pre_loadvm(cpu);
+    }
+    if (whpx_enabled()) {
+        whpx_cpu_synchronize_pre_loadvm(cpu);
+    }
+}
+
+int64_t cpus_get_virtual_clock(void)
+{
+    if (cpus_accel && cpus_accel->get_virtual_clock) {
+        return cpus_accel->get_virtual_clock();
+    }
+    if (icount_enabled()) {
+        return icount_get();
+    } else if (qtest_enabled()) { /* for qtest_clock_warp */
+        return qtest_get_virtual_clock();
+    }
+    return cpu_get_clock();
+}
+
+/*
+ * return the time elapsed in VM between vm_start and vm_stop.  Unless
+ * icount is active, cpus_get_elapsed_ticks() uses units of the host CPU cycle
+ * counter.
+ */
+int64_t cpus_get_elapsed_ticks(void)
+{
+    if (cpus_accel && cpus_accel->get_elapsed_ticks) {
+        return cpus_accel->get_elapsed_ticks();
+    }
+    if (icount_enabled()) {
+        return icount_get();
+    }
+    return cpu_get_ticks();
+}
+
 static int do_vm_stop(RunState state, bool send_stop)
 {
     int ret = 0;
@@ -279,7 +380,7 @@  int vm_shutdown(void)
     return do_vm_stop(RUN_STATE_SHUTDOWN, false);
 }
 
-static bool cpu_can_run(CPUState *cpu)
+bool cpu_can_run(CPUState *cpu)
 {
     if (cpu->stop) {
         return false;
@@ -290,7 +391,7 @@  static bool cpu_can_run(CPUState *cpu)
     return true;
 }
 
-static void cpu_handle_guest_debug(CPUState *cpu)
+void cpu_handle_guest_debug(CPUState *cpu)
 {
     gdb_set_stop_cpu(cpu);
     qemu_system_debug_request();
@@ -396,7 +497,7 @@  static void qemu_cpu_stop(CPUState *cpu, bool exit)
     qemu_cond_broadcast(&qemu_pause_cond);
 }
 
-static void qemu_wait_io_event_common(CPUState *cpu)
+void qemu_wait_io_event_common(CPUState *cpu)
 {
     atomic_mb_set(&cpu->thread_kicked, false);
     if (cpu->stop) {
@@ -421,7 +522,7 @@  static void qemu_tcg_rr_wait_io_event(void)
     }
 }
 
-static void qemu_wait_io_event(CPUState *cpu)
+void qemu_wait_io_event(CPUState *cpu)
 {
     bool slept = false;
 
@@ -437,8 +538,8 @@  static void qemu_wait_io_event(CPUState *cpu)
     }
 
 #ifdef _WIN32
-    /* Eat dummy APC queued by qemu_cpu_kick_thread.  */
-    if (!tcg_enabled()) {
+    /* Eat dummy APC queued by cpus_kick_thread. */
+    if (hax_enabled()) {
         SleepEx(0, TRUE);
     }
 #endif
@@ -467,8 +568,7 @@  static void *qemu_kvm_cpu_thread_fn(void *arg)
     kvm_init_cpu_signals(cpu);
 
     /* signal CPU creation */
-    cpu->created = true;
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_created(cpu);
     qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
@@ -482,8 +582,7 @@  static void *qemu_kvm_cpu_thread_fn(void *arg)
     } while (!cpu->unplug || cpu_can_run(cpu));
 
     qemu_kvm_destroy_vcpu(cpu);
-    cpu->created = false;
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_destroyed(cpu);
     qemu_mutex_unlock_iothread();
     rcu_unregister_thread();
     return NULL;
@@ -511,8 +610,7 @@  static void *qemu_dummy_cpu_thread_fn(void *arg)
     sigaddset(&waitset, SIG_IPI);
 
     /* signal CPU creation */
-    cpu->created = true;
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_created(cpu);
     qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
@@ -660,8 +758,7 @@  static void deal_with_unplugged_cpus(void)
     CPU_FOREACH(cpu) {
         if (cpu->unplug && !cpu_can_run(cpu)) {
             qemu_tcg_destroy_vcpu(cpu);
-            cpu->created = false;
-            qemu_cond_signal(&qemu_cpu_cond);
+            cpu_thread_signal_destroyed(cpu);
             break;
         }
     }
@@ -688,9 +785,8 @@  static void *qemu_tcg_rr_cpu_thread_fn(void *arg)
     qemu_thread_get_self(cpu->thread);
 
     cpu->thread_id = qemu_get_thread_id();
-    cpu->created = true;
     cpu->can_do_io = 1;
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_created(cpu);
     qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     /* wait for initial kick-off after machine start */
@@ -800,11 +896,9 @@  static void *qemu_hax_cpu_thread_fn(void *arg)
     qemu_thread_get_self(cpu->thread);
 
     cpu->thread_id = qemu_get_thread_id();
-    cpu->created = true;
     current_cpu = cpu;
-
     hax_init_vcpu(cpu);
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_created(cpu);
     qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
@@ -843,8 +937,7 @@  static void *qemu_hvf_cpu_thread_fn(void *arg)
     hvf_init_vcpu(cpu);
 
     /* signal CPU creation */
-    cpu->created = true;
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_created(cpu);
     qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
@@ -858,8 +951,7 @@  static void *qemu_hvf_cpu_thread_fn(void *arg)
     } while (!cpu->unplug || cpu_can_run(cpu));
 
     hvf_vcpu_destroy(cpu);
-    cpu->created = false;
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_destroyed(cpu);
     qemu_mutex_unlock_iothread();
     rcu_unregister_thread();
     return NULL;
@@ -884,8 +976,7 @@  static void *qemu_whpx_cpu_thread_fn(void *arg)
     }
 
     /* signal CPU creation */
-    cpu->created = true;
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_created(cpu);
     qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
@@ -902,8 +993,7 @@  static void *qemu_whpx_cpu_thread_fn(void *arg)
     } while (!cpu->unplug || cpu_can_run(cpu));
 
     whpx_destroy_vcpu(cpu);
-    cpu->created = false;
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_destroyed(cpu);
     qemu_mutex_unlock_iothread();
     rcu_unregister_thread();
     return NULL;
@@ -936,10 +1026,9 @@  static void *qemu_tcg_cpu_thread_fn(void *arg)
     qemu_thread_get_self(cpu->thread);
 
     cpu->thread_id = qemu_get_thread_id();
-    cpu->created = true;
     cpu->can_do_io = 1;
     current_cpu = cpu;
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_created(cpu);
     qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     /* process any pending work */
@@ -980,14 +1069,13 @@  static void *qemu_tcg_cpu_thread_fn(void *arg)
     } while (!cpu->unplug || cpu_can_run(cpu));
 
     qemu_tcg_destroy_vcpu(cpu);
-    cpu->created = false;
-    qemu_cond_signal(&qemu_cpu_cond);
+    cpu_thread_signal_destroyed(cpu);
     qemu_mutex_unlock_iothread();
     rcu_unregister_thread();
     return NULL;
 }
 
-static void qemu_cpu_kick_thread(CPUState *cpu)
+void cpus_kick_thread(CPUState *cpu)
 {
 #ifndef _WIN32
     int err;
@@ -1017,7 +1105,10 @@  static void qemu_cpu_kick_thread(CPUState *cpu)
 void qemu_cpu_kick(CPUState *cpu)
 {
     qemu_cond_broadcast(cpu->halt_cond);
-    if (tcg_enabled()) {
+
+    if (cpus_accel && cpus_accel->kick_vcpu_thread) {
+        cpus_accel->kick_vcpu_thread(cpu);
+    } else if (tcg_enabled()) {
         if (qemu_tcg_mttcg_enabled()) {
             cpu_exit(cpu);
         } else {
@@ -1031,14 +1122,14 @@  void qemu_cpu_kick(CPUState *cpu)
              */
             cpu->exit_request = 1;
         }
-        qemu_cpu_kick_thread(cpu);
+        cpus_kick_thread(cpu);
     }
 }
 
 void qemu_cpu_kick_self(void)
 {
     assert(current_cpu);
-    qemu_cpu_kick_thread(current_cpu);
+    cpus_kick_thread(current_cpu);
 }
 
 bool qemu_cpu_is_self(CPUState *cpu)
@@ -1088,6 +1179,21 @@  void qemu_cond_timedwait_iothread(QemuCond *cond, int ms)
     qemu_cond_timedwait(cond, &qemu_global_mutex, ms);
 }
 
+/* signal CPU creation */
+void cpu_thread_signal_created(CPUState *cpu)
+{
+    cpu->created = true;
+    qemu_cond_signal(&qemu_cpu_cond);
+}
+
+/* signal CPU destruction */
+void cpu_thread_signal_destroyed(CPUState *cpu)
+{
+    cpu->created = false;
+    qemu_cond_signal(&qemu_cpu_cond);
+}
+
+
 static bool all_vcpus_paused(void)
 {
     CPUState *cpu;
@@ -1163,9 +1269,6 @@  void cpu_remove_sync(CPUState *cpu)
     qemu_mutex_lock_iothread();
 }
 
-/* For temporary buffers for forming a name */
-#define VCPU_THREAD_NAME_SIZE 16
-
 static void qemu_tcg_init_vcpu(CPUState *cpu)
 {
     char thread_name[VCPU_THREAD_NAME_SIZE];
@@ -1286,6 +1389,13 @@  static void qemu_whpx_start_vcpu(CPUState *cpu)
 #endif
 }
 
+void cpus_register_accel(CpusAccel *ca)
+{
+    assert(ca != NULL);
+    assert(ca->create_vcpu_thread != NULL); /* mandatory */
+    cpus_accel = ca;
+}
+
 static void qemu_dummy_start_vcpu(CPUState *cpu)
 {
     char thread_name[VCPU_THREAD_NAME_SIZE];
@@ -1316,7 +1426,10 @@  void qemu_init_vcpu(CPUState *cpu)
         cpu_address_space_init(cpu, 0, "cpu-memory", cpu->memory);
     }
 
-    if (kvm_enabled()) {
+    if (cpus_accel) {
+        /* accelerator already implements the CpusAccel interface */
+        cpus_accel->create_vcpu_thread(cpu);
+    } else if (kvm_enabled()) {
         qemu_kvm_start_vcpu(cpu);
     } else if (hax_enabled()) {
         qemu_hax_start_vcpu(cpu);
diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
index e97ad407fa..16345eec43 100644
--- a/stubs/Makefile.objs
+++ b/stubs/Makefile.objs
@@ -1,6 +1,7 @@ 
 stub-obj-y += blk-commit-all.o
 stub-obj-y += cmos.o
 stub-obj-y += cpu-get-clock.o
+stub-obj-y += cpus-get-virtual-clock.o
 stub-obj-y += qemu-timer-notify-cb.o
 stub-obj-y += icount.o
 stub-obj-y += dump.o
@@ -28,6 +29,7 @@  stub-obj-y += trace-control.o
 stub-obj-y += vmgenid.o
 stub-obj-y += vmstate.o
 stub-obj-$(CONFIG_SOFTMMU) += win32-kbd-hook.o
+stub-obj-y += cpu-synchronize-state.o
 
 #######################################################################
 # code used by both qemu system emulation and qemu-img
diff --git a/stubs/cpu-synchronize-state.c b/stubs/cpu-synchronize-state.c
new file mode 100644
index 0000000000..3112fe439d
--- /dev/null
+++ b/stubs/cpu-synchronize-state.c
@@ -0,0 +1,15 @@ 
+#include "qemu/osdep.h"
+#include "sysemu/hw_accel.h"
+
+void cpu_synchronize_state(CPUState *cpu)
+{
+}
+void cpu_synchronize_post_reset(CPUState *cpu)
+{
+}
+void cpu_synchronize_post_init(CPUState *cpu)
+{
+}
+void cpu_synchronize_pre_loadvm(CPUState *cpu)
+{
+}
diff --git a/stubs/cpus-get-virtual-clock.c b/stubs/cpus-get-virtual-clock.c
new file mode 100644
index 0000000000..fd447d53f3
--- /dev/null
+++ b/stubs/cpus-get-virtual-clock.c
@@ -0,0 +1,8 @@ 
+#include "qemu/osdep.h"
+#include "sysemu/cpu-timers.h"
+#include "qemu/main-loop.h"
+
+int64_t cpus_get_virtual_clock(void)
+{
+    return cpu_get_clock();
+}
diff --git a/util/qemu-timer.c b/util/qemu-timer.c
index db51e68f25..50b325c65b 100644
--- a/util/qemu-timer.c
+++ b/util/qemu-timer.c
@@ -635,13 +635,7 @@  int64_t qemu_clock_get_ns(QEMUClockType type)
         return get_clock();
     default:
     case QEMU_CLOCK_VIRTUAL:
-        if (icount_enabled()) {
-            return icount_get();
-        } else if (qtest_enabled()) { /* for qtest_clock_warp */
-            return qtest_get_virtual_clock();
-        } else {
-            return cpu_get_clock();
-        }
+        return cpus_get_virtual_clock();
     case QEMU_CLOCK_HOST:
         return REPLAY_CLOCK(REPLAY_CLOCK_HOST, get_clock_realtime());
     case QEMU_CLOCK_VIRTUAL_RT: