[PATCH v2 2/3] KVM: keep track of running ioctls

[Emanuele Giuseppe Esposito <eesposit@xxxxxxxxxx>]

Using the new accel-blocker API, mark where ioctls are being called
in KVM. Next, we will implement the critical section that will take
care of performing memslots modifications atomically, therefore
preventing any new ioctl from running and allowing the running ones
to finish.

Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@xxxxxxxxxx>
---
 accel/kvm/kvm-all.c   | 7 +++++++
 hw/core/cpu-common.c  | 2 ++
 include/hw/core/cpu.h | 3 +++
 3 files changed, 12 insertions(+)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index f99b0becd8..dfc6fe76db 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2310,6 +2310,7 @@ static int kvm_init(MachineState *ms)
     assert(TARGET_PAGE_SIZE <= qemu_real_host_page_size());
 
     s->sigmask_len = 8;
+    accel_blocker_init();
 
 #ifdef KVM_CAP_SET_GUEST_DEBUG
     QTAILQ_INIT(&s->kvm_sw_breakpoints);
@@ -3014,7 +3015,9 @@ int kvm_vm_ioctl(KVMState *s, int type, ...)
     va_end(ap);
 
     trace_kvm_vm_ioctl(type, arg);
+    accel_set_in_ioctl(true);
     ret = ioctl(s->vmfd, type, arg);
+    accel_set_in_ioctl(false);
     if (ret == -1) {
         ret = -errno;
     }
@@ -3032,7 +3035,9 @@ int kvm_vcpu_ioctl(CPUState *cpu, int type, ...)
     va_end(ap);
 
     trace_kvm_vcpu_ioctl(cpu->cpu_index, type, arg);
+    accel_cpu_set_in_ioctl(cpu, true);
     ret = ioctl(cpu->kvm_fd, type, arg);
+    accel_cpu_set_in_ioctl(cpu, false);
     if (ret == -1) {
         ret = -errno;
     }
@@ -3050,7 +3055,9 @@ int kvm_device_ioctl(int fd, int type, ...)
     va_end(ap);
 
     trace_kvm_device_ioctl(fd, type, arg);
+    accel_set_in_ioctl(true);
     ret = ioctl(fd, type, arg);
+    accel_set_in_ioctl(false);
     if (ret == -1) {
         ret = -errno;
     }
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);
-- 
2.31.1