On Fri, Nov 20, 2015 at 06:24:33PM +0530, Bharata B Rao wrote: > From: Gu Zheng <guz.f...@cn.fujitsu.com> > > 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.f...@cn.fujitsu.com> > Signed-off-by: Gu Zheng <guz.f...@cn.fujitsu.com> > Signed-off-by: Zhu Guihua <zhugh.f...@cn.fujitsu.com> > Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com> > [- Explicit CPU_REMOVE() from qemu_kvm/tcg_destroy_vcpu() > isn't needed as it is done from cpu_exec_exit()] > --- > cpus.c | 41 +++++++++++++++++++++++++++++++++++++ > include/qom/cpu.h | 10 +++++++++ > include/sysemu/kvm.h | 1 + > kvm-all.c | 57 > +++++++++++++++++++++++++++++++++++++++++++++++++++- > kvm-stub.c | 5 +++++ > 5 files changed, 113 insertions(+), 1 deletion(-) > > diff --git a/cpus.c b/cpus.c > index 877bd70..af2b274 100644 > --- a/cpus.c > +++ b/cpus.c > @@ -953,6 +953,21 @@ 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.\n"); > + exit(EXIT_FAILURE); > + } > + > + object_unparent(OBJECT(cpu)); > +} > + > +static void qemu_tcg_destroy_vcpu(CPUState *cpu) > +{ > + object_unparent(OBJECT(cpu)); > +} > + > static void flush_queued_work(CPUState *cpu) > { > struct qemu_work_item *wi; > @@ -1053,6 +1068,11 @@ 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);
This looks like a change to locking semantics, and I can't see the
connection to the described purpose of the patch.
> + return NULL;
> + }
> }
>
> return NULL;
> @@ -1108,6 +1128,7 @@ 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();
>
> @@ -1145,6 +1166,16 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
> }
> }
> qemu_tcg_wait_io_event(QTAILQ_FIRST(&cpus));
> + CPU_FOREACH(cpu) {
> + if (cpu->exit && !cpu_can_run(cpu)) {
> + remove_cpu = cpu;
> + break;
> + }
> + }
> + if (remove_cpu) {
> + qemu_tcg_destroy_vcpu(remove_cpu);
> + remove_cpu = NULL;
> + }
Any particular reason to only cleanup one cpu per iteration?
Also, any particular reason this isn't folded into tcg_exec_all with
the other cpu->exit logic?
> }
>
> return NULL;
> @@ -1301,6 +1332,13 @@ void resume_all_vcpus(void)
> }
> }
>
> +void cpu_remove(CPUState *cpu)
> +{
> + cpu->stop = true;
> + cpu->exit = true;
> + qemu_cpu_kick(cpu);
> +}
> +
> /* For temporary buffers for forming a name */
> #define VCPU_THREAD_NAME_SIZE 16
>
> @@ -1506,6 +1544,9 @@ static void tcg_exec_all(void)
> break;
> }
> } else if (cpu->stop || cpu->stopped) {
> + if (cpu->exit) {
> + next_cpu = CPU_NEXT(cpu);
> + }
> break;
> }
> }
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index 51a1323..67e05b0 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -223,6 +223,7 @@ struct kvm_run;
> * @halted: Nonzero if the CPU is in suspended state.
> * @stop: Indicates a pending stop request.
> * @stopped: Indicates the CPU has been artificially stopped.
> + * @exit: Indicates the CPU has exited due to an unplug operation.
> * @crash_occurred: Indicates the OS reported a crash (panic) for this CPU
> * @tcg_exit_req: Set to force TCG to stop executing linked TBs for this
> * CPU and return to its top level loop.
> @@ -274,6 +275,7 @@ struct CPUState {
> bool created;
> bool stop;
> bool stopped;
> + bool exit;
> bool crash_occurred;
> bool exit_request;
> uint32_t interrupt_request;
> @@ -696,6 +698,14 @@ void cpu_exit(CPUState *cpu);
> void cpu_resume(CPUState *cpu);
>
> /**
> + * cpu_remove:
> + * @cpu: The CPU to remove.
> + *
> + * Requests the CPU to be removed.
> + */
> +void cpu_remove(CPUState *cpu);
> +
> +/**
> * qemu_init_vcpu:
> * @cpu: The vCPU to initialize.
> *
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index b31f325..dd1b783 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -206,6 +206,7 @@ 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 c648b81..3befc59 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -60,6 +60,12 @@
>
> #define KVM_MSI_HASHTAB_SIZE 256
>
> +struct KVMParkedVcpu {
> + unsigned long vcpu_id;
> + int kvm_fd;
> + QLIST_ENTRY(KVMParkedVcpu) node;
> +};
> +
> struct KVMState
> {
> AccelState parent_obj;
> @@ -93,6 +99,7 @@ struct KVMState
> QTAILQ_HEAD(msi_hashtab, KVMMSIRoute) msi_hashtab[KVM_MSI_HASHTAB_SIZE];
> #endif
> KVMMemoryListener memory_listener;
> + QLIST_HEAD(, KVMParkedVcpu) kvm_parked_vcpus;
> };
>
> KVMState *kvm_state;
> @@ -235,6 +242,53 @@ static int kvm_set_user_memory_region(KVMMemoryListener
> *kml, KVMSlot *slot)
> return kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem);
> }
>
> +int kvm_destroy_vcpu(CPUState *cpu)
> +{
> + KVMState *s = kvm_state;
> + long mmap_size;
> + struct KVMParkedVcpu *vcpu = NULL;
> + 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;
> + }
> +
> + vcpu = g_malloc0(sizeof(*vcpu));
> + vcpu->vcpu_id = kvm_arch_vcpu_id(cpu);
> + vcpu->kvm_fd = cpu->kvm_fd;
> + QLIST_INSERT_HEAD(&kvm_state->kvm_parked_vcpus, vcpu, node);
> +err:
> + return ret;
> +}
> +
> +static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id)
> +{
> + struct KVMParkedVcpu *cpu;
> +
> + QLIST_FOREACH(cpu, &s->kvm_parked_vcpus, node) {
> + if (cpu->vcpu_id == vcpu_id) {
> + int kvm_fd;
> +
> + QLIST_REMOVE(cpu, node);
> + kvm_fd = cpu->kvm_fd;
> + g_free(cpu);
> + return kvm_fd;
> + }
> + }
Hmm.. use of a simple list here does mean that unplugging, then
replugging all (except 1) vcpus would be an O(n^2) operation. That's
probably still alright, I guess.
> +
> + return kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)vcpu_id);
> +}
> +
> int kvm_init_vcpu(CPUState *cpu)
> {
> KVMState *s = kvm_state;
> @@ -243,7 +297,7 @@ int kvm_init_vcpu(CPUState *cpu)
>
> DPRINTF("kvm_init_vcpu\n");
>
> - ret = kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)kvm_arch_vcpu_id(cpu));
> + ret = kvm_get_vcpu(s, kvm_arch_vcpu_id(cpu));
> if (ret < 0) {
> DPRINTF("kvm_create_vcpu failed\n");
> goto err;
> @@ -1468,6 +1522,7 @@ static int kvm_init(MachineState *ms)
> #ifdef KVM_CAP_SET_GUEST_DEBUG
> QTAILQ_INIT(&s->kvm_sw_breakpoints);
> #endif
> + QLIST_INIT(&s->kvm_parked_vcpus);
> s->vmfd = -1;
> s->fd = qemu_open("/dev/kvm", O_RDWR);
> if (s->fd == -1) {
> diff --git a/kvm-stub.c b/kvm-stub.c
> index dc97a5e..0b39456 100644
> --- a/kvm-stub.c
> +++ b/kvm-stub.c
> @@ -32,6 +32,11 @@ bool kvm_allowed;
> bool kvm_readonly_mem_allowed;
> bool kvm_ioeventfd_any_length_allowed;
>
> +int kvm_destroy_vcpu(CPUState *cpu)
> +{
> + return -ENOSYS;
> +}
> +
> int kvm_init_vcpu(CPUState *cpu)
> {
> return -ENOSYS;
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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