| Message ID | 1457074461-14285-4-git-send-email-bharata@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 04.03.2016 07:54, Bharata B Rao wrote: > From: Gu Zheng <guz.fnst@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.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: David Gibson <david@gibson.dropbear.id.au> > --- > cpus.c | 38 +++++++++++++++++++++++++++++++++++ > include/qom/cpu.h | 10 +++++++++ > include/sysemu/kvm.h | 1 + > kvm-all.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++- > kvm-stub.c | 5 +++++ > 5 files changed, 110 insertions(+), 1 deletion(-) > > diff --git a/cpus.c b/cpus.c > index 9592163..07cc054 100644 > --- a/cpus.c > +++ b/cpus.c > @@ -953,6 +953,18 @@ 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; > @@ -1053,6 +1065,11 @@ 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_iothread(); > + return NULL; > + } My comment from last time still applies: You could increase readability of the code by changing the condition of the loop instead - currently it is a "while (1)" ... you could turn that into a "do { ... } while (!cpu->exit || cpu_can_run(cpu))" and then destroy the cpu after the loop. > } > > return NULL; > @@ -1108,6 +1125,7 @@ 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 +1163,16 @@ 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; > + } > } > > return NULL; > @@ -1301,6 +1329,13 @@ 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 > > @@ -1517,6 +1552,9 @@ 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 7052eee..6e5171b 100644 > --- a/include/qom/cpu.h > +++ b/include/qom/cpu.h > @@ -237,6 +237,7 @@ 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. > @@ -289,6 +290,7 @@ struct CPUState { > bool created; > bool stop; > bool stopped; > + bool exit; Another comment from last review: There is also a "exit_request" member in this struct already ... maybe you could name the new variable differently to avoid confusion? Something like "remove_request" or "unplug_request" ? > bool crash_occurred; > bool exit_request; > uint32_t interrupt_request; ... Apart from that, the patch looks fine to me. Thomas
On Mon, Mar 07, 2016 at 08:05:58PM +0100, Thomas Huth wrote: > On 04.03.2016 07:54, Bharata B Rao wrote: > > From: Gu Zheng <guz.fnst@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.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: David Gibson <david@gibson.dropbear.id.au> > > --- > > cpus.c | 38 +++++++++++++++++++++++++++++++++++ > > include/qom/cpu.h | 10 +++++++++ > > include/sysemu/kvm.h | 1 + > > kvm-all.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++- > > kvm-stub.c | 5 +++++ > > 5 files changed, 110 insertions(+), 1 deletion(-) > > > > diff --git a/cpus.c b/cpus.c > > index 9592163..07cc054 100644 > > --- a/cpus.c > > +++ b/cpus.c > > @@ -953,6 +953,18 @@ 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; > > @@ -1053,6 +1065,11 @@ 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_iothread(); > > + return NULL; > > + } > > My comment from last time still applies: > > You could increase readability of the code by changing the condition of > the loop instead - currently it is a "while (1)" ... you could turn that > into a "do { ... } while (!cpu->exit || cpu_can_run(cpu))" and then > destroy the cpu after the loop. Sorry for missing this, will take of this and the other comment in this thread in the next version. Regards, Bharata.
diff --git a/cpus.c b/cpus.c index 9592163..07cc054 100644 --- a/cpus.c +++ b/cpus.c @@ -953,6 +953,18 @@ 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; @@ -1053,6 +1065,11 @@ 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_iothread(); + return NULL; + } } return NULL; @@ -1108,6 +1125,7 @@ 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 +1163,16 @@ 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; + } } return NULL; @@ -1301,6 +1329,13 @@ 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 @@ -1517,6 +1552,9 @@ 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 7052eee..6e5171b 100644 --- a/include/qom/cpu.h +++ b/include/qom/cpu.h @@ -237,6 +237,7 @@ 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. @@ -289,6 +290,7 @@ struct CPUState { bool created; bool stop; bool stopped; + bool exit; bool crash_occurred; bool exit_request; uint32_t interrupt_request; @@ -756,6 +758,14 @@ 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 6695fa7..5d5b602 100644 --- a/include/sysemu/kvm.h +++ b/include/sysemu/kvm.h @@ -216,6 +216,7 @@ 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 a65e73f..b41ff46 100644 --- a/kvm-all.c +++ b/kvm-all.c @@ -61,6 +61,12 @@ #define KVM_MSI_HASHTAB_SIZE 256 +struct KVMParkedVcpu { + unsigned long vcpu_id; + int kvm_fd; + QLIST_ENTRY(KVMParkedVcpu) node; +}; + struct KVMState { AccelState parent_obj; @@ -94,6 +100,7 @@ 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; @@ -237,6 +244,53 @@ 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; + } + } + + return kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)vcpu_id); +} + int kvm_init_vcpu(CPUState *cpu) { KVMState *s = kvm_state; @@ -245,7 +299,7 @@ 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; @@ -1508,6 +1562,7 @@ 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 b962b24..61f9d5c 100644 --- a/kvm-stub.c +++ b/kvm-stub.c @@ -33,6 +33,11 @@ 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;