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cpu: Reclaim vCPU objects

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In order to deal well with the kvm vcpus (which can not be removed without any
protection), we do not close KVM vcpu fd, just record and mark it as stopped
into a list, so that we can reuse it for the appending cpu hot-add request if
possible. It is also the approach that kvm guys suggested:
https://www.mail-archive.com/kvm@vger.kernel.org/msg102839.html

Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Zhu Guihua <zhugh.fnst@cn.fujitsu.com>
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
               [- Explicit CPU_REMOVE() from qemu_kvm/tcg_destroy_vcpu()
                  isn't needed as it is done from cpu_exec_exit()
                - Use iothread mutex instead of global mutex during
                  destroy
                - Don't cleanup vCPU object from vCPU thread context
                  but leave it to the callers (device_add/device_del)]
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Gu Zheng 2016-05-12 09:18:13 +05:30 • committed by David Gibson
parent 9dfeca7c6b
commit 4c055ab54f
5 changed files with 109 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

39
cpus.c
View file

@ -972,6 +972,18 @@ 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)
{
if (kvm_destroy_vcpu(cpu) < 0) {
error_report("kvm_destroy_vcpu failed");
exit(EXIT_FAILURE);
}
}
static void qemu_tcg_destroy_vcpu(CPUState *cpu)
{
}
static void flush_queued_work(CPUState *cpu)
{
struct qemu_work_item *wi;
@ -1061,7 +1073,7 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
cpu->created = true;
qemu_cond_signal(&qemu_cpu_cond);
while (1) {
do {
if (cpu_can_run(cpu)) {
r = kvm_cpu_exec(cpu);
if (r == EXCP_DEBUG) {
@ -1069,8 +1081,10 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
}
}
qemu_kvm_wait_io_event(cpu);
}
} while (!cpu->unplug || cpu_can_run(cpu));
qemu_kvm_destroy_vcpu(cpu);
qemu_mutex_unlock_iothread();
return NULL;
}
@ -1124,6 +1138,7 @@ static void tcg_exec_all(void);
static void *qemu_tcg_cpu_thread_fn(void *arg)
{
CPUState *cpu = arg;
CPUState *remove_cpu = NULL;
rcu_register_thread();
@ -1161,6 +1176,16 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
}
}
qemu_tcg_wait_io_event(QTAILQ_FIRST(&cpus));
CPU_FOREACH(cpu) {
if (cpu->unplug && !cpu_can_run(cpu)) {
remove_cpu = cpu;
break;
}
}
if (remove_cpu) {
qemu_tcg_destroy_vcpu(remove_cpu);
remove_cpu = NULL;
}
}
return NULL;
@ -1317,6 +1342,13 @@ void resume_all_vcpus(void)
}
}
void cpu_remove(CPUState *cpu)
{
cpu->stop = true;
cpu->unplug = true;
qemu_cpu_kick(cpu);
}
/* For temporary buffers for forming a name */
#define VCPU_THREAD_NAME_SIZE 16
@ -1533,6 +1565,9 @@ static void tcg_exec_all(void)
break;
}
} else if (cpu->stop || cpu->stopped) {
if (cpu->unplug) {
next_cpu = CPU_NEXT(cpu);
}
break;
}
}