[Qemu-devel] [RFC][PATCH 2/6] cpus: release allocated vcpu objects and exit vcpu thread

[Chen Fan]

After ACPI get a signal to eject a vcpu, then it will notify
the vcpu thread of needing to exit, before the vcpu exiting,
will release the vcpu related objects.

Signed-off-by: Chen Fan <address@hidden>
---
 cpus.c               | 36 ++++++++++++++++++++++++++++++++++++
 hw/acpi/piix4.c      | 16 ++++++++++++----
 include/qom/cpu.h    |  9 +++++++++
 include/sysemu/kvm.h |  1 +
 kvm-all.c            | 26 ++++++++++++++++++++++++++
 5 files changed, 84 insertions(+), 4 deletions(-)

diff --git a/cpus.c b/cpus.c
index 70cc617..6b793cb 100644
--- a/cpus.c
+++ b/cpus.c
@@ -697,6 +697,30 @@ void async_run_on_cpu(CPUState *cpu, void (*func)(void 
*data), void *data)
     qemu_cpu_kick(cpu);
 }
 
+static void qemu_kvm_destroy_vcpu(CPUState *cpu)
+{
+    CPUState *pcpu, *pcpu1;
+
+    pcpu = first_cpu;
+    pcpu1 = NULL;
+
+    while (pcpu) {
+        if (pcpu == cpu && pcpu1) {
+            pcpu1->next_cpu = cpu->next_cpu;
+            break;
+        }
+        pcpu1 = pcpu;
+        pcpu = pcpu->next_cpu;
+    }
+
+    if (kvm_destroy_vcpu(cpu) < 0) {
+        fprintf(stderr, "kvm_destroy_vcpu failed.\n");
+        exit(1);
+    }
+
+    qdev_free(DEVICE(X86_CPU(cpu)));
+}
+
 static void flush_queued_work(CPUState *cpu)
 {
     struct qemu_work_item *wi;
@@ -788,6 +812,11 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
             }
         }
         qemu_kvm_wait_io_event(cpu);
+        if (cpu->exit && !cpu_can_run(cpu)) {
+            qemu_kvm_destroy_vcpu(cpu);
+            qemu_mutex_unlock(&qemu_global_mutex);
+            return NULL;
+        }
     }
 
     return NULL;
@@ -1080,6 +1109,13 @@ static void qemu_dummy_start_vcpu(CPUState *cpu)
     }
 }
 
+void qemu_down_vcpu(CPUState *cpu)
+{
+    cpu->stop = true;
+    cpu->exit = true;
+    qemu_cpu_kick(cpu);
+}
+
 void qemu_init_vcpu(CPUState *cpu)
 {
     cpu->nr_cores = smp_cores;
diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index 1aaa7a4..44bc809 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -611,10 +611,18 @@ static const MemoryRegionOps piix4_pci_ops = {
     },
 };
 
-static void acpi_piix_eject_vcpu(int64_t cpuid)
+static void acpi_piix_eject_vcpu(PIIX4PMState *s, int64_t cpuid)
 {
-    /* TODO: eject a vcpu, release allocated vcpu and exit the vcpu pthread.  
*/
-    PIIX4_DPRINTF("vcpu: %" PRIu64 " need to be ejected.\n", cpuid);
+    CPUStatus *cpus = &s->gpe_cpu;
+    CPUState *cs = NULL;
+
+    cs = qemu_get_cpu(cpuid);
+    if (cs == NULL) {
+        return;
+    }
+
+    cpus->old_sts[cpuid / 8] &= ~(1 << (cpuid % 8));
+    qemu_down_vcpu(cs);
 }
 
 static uint64_t cpu_status_read(void *opaque, hwaddr addr, unsigned int size)
@@ -647,7 +655,7 @@ static void cpu_status_write(void *opaque, hwaddr addr, 
uint64_t data,
     }
 
     if (cpuid != 0) {
-        acpi_piix_eject_vcpu(cpuid);
+        acpi_piix_eject_vcpu(s, cpuid);
     }
 }
 
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 3e49936..fa8ec8a 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -180,6 +180,7 @@ struct CPUState {
     bool created;
     bool stop;
     bool stopped;
+    bool exit;
     volatile sig_atomic_t exit_request;
     volatile sig_atomic_t tcg_exit_req;
     uint32_t interrupt_request;
@@ -489,6 +490,14 @@ void cpu_exit(CPUState *cpu);
 void cpu_resume(CPUState *cpu);
 
 /**
+ * qemu_down_vcpu:
+ * @cpu: The vCPU will to down.
+ *
+ * Down a vCPU.
+ */
+void qemu_down_vcpu(CPUState *cpu);
+
+/**
  * qemu_init_vcpu:
  * @cpu: The vCPU to initialize.
  *
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index de74411..fd85605 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -158,6 +158,7 @@ int kvm_has_intx_set_mask(void);
 
 int kvm_init_vcpu(CPUState *cpu);
 int kvm_cpu_exec(CPUState *cpu);
+int kvm_destroy_vcpu(CPUState *cpu);
 
 #ifdef NEED_CPU_H
 
diff --git a/kvm-all.c b/kvm-all.c
index 716860f..fda3601 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -225,6 +225,32 @@ static void kvm_reset_vcpu(void *opaque)
     kvm_arch_reset_vcpu(cpu);
 }
 
+int kvm_destroy_vcpu(CPUState *cpu)
+{
+    KVMState *s = kvm_state;
+    long mmap_size;
+    int ret = 0;
+
+    DPRINTF("kvm_destroy_vcpu\n");
+
+    mmap_size = kvm_ioctl(s, KVM_GET_VCPU_MMAP_SIZE, 0);
+    if (mmap_size < 0) {
+        ret = mmap_size;
+        DPRINTF("KVM_GET_VCPU_MMAP_SIZE failed\n");
+        goto err;
+    }
+
+    ret = munmap(cpu->kvm_run, mmap_size);
+    if (ret < 0) {
+        goto err;
+    }
+
+    close(cpu->kvm_fd);
+
+err:
+    return ret;
+}
+
 int kvm_init_vcpu(CPUState *cpu)
 {
     KVMState *s = kvm_state;
-- 
1.8.1.4