Re: [Qemu-devel] [RFC V2 09/10] cpu hotplug: implement function cpu_status_write() for vcpu ejection

[Igor Mammedov <imammedo@redhat.com>]

On Thu, 28 Aug 2014 11:36:41 +0800
Gu Zheng <guz.fnst@cn.fujitsu.com> wrote:

> From: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> 
> When OS ejected a vcpu (like: echo 1 > /sys/bus/acpi/devices/LNXCPUXX/eject),
> it would call acpi EJ0 method, the firmware need to write the new cpumap, QEMU
> would know which vcpu need to be ejected.
> 
> TODO:
> -confirm the hotplug result via OST if guest support it.
> 
> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
> ---
>  cpus.c                            |    7 ++++++
>  hw/acpi/cpu_hotplug.c             |   40 ++++++++++++++++++++++++++++++++++++-
>  hw/i386/acpi-dsdt-cpu-hotplug.dsl |    6 ++++-
>  include/hw/acpi/cpu_hotplug.h     |    1 +
>  include/qom/cpu.h                 |    9 ++++++++
>  5 files changed, 61 insertions(+), 2 deletions(-)
> 
> diff --git a/cpus.c b/cpus.c
> index cce2744..eee693b 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -1182,6 +1182,13 @@ 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
>  
> diff --git a/hw/acpi/cpu_hotplug.c b/hw/acpi/cpu_hotplug.c
> index 56cb316..7cbce69 100644
> --- a/hw/acpi/cpu_hotplug.c
> +++ b/hw/acpi/cpu_hotplug.c
> @@ -20,10 +20,46 @@ static uint64_t cpu_status_read(void *opaque, hwaddr addr, unsigned int size)
>      return val;
>  }
>  
> +static void acpi_eject_vcpu(AcpiCpuHotplug *cpus_status, int64_t cpu_id)
> +{
> +    CPUState *cpu;
> +
> +    CPU_FOREACH(cpu) {
> +        CPUClass *cc = CPU_GET_CLASS(cpu);
> +        int64_t id = cc->get_arch_id(cpu);
> +
> +        if (cpu_id == id) {
> +            cpus_status->old_sts[cpu_id / 8] &= ~(1 << (cpu_id % 8));
> +            cpus_status->sts[cpu_id / 8] &= ~(1 << (cpu_id % 8));
> +            cpu_remove(cpu);
Could CPU be destoyed at this time, instead of marking it destruction?

> +            break;
> +        }
> +    }
> +}
> +
>  static void cpu_status_write(void *opaque, hwaddr addr, uint64_t data,
>                               unsigned int size)
>  {
> -    /* TODO: implement VCPU removal on guest signal that CPU can be removed */
> +    AcpiCpuHotplug *cpus = opaque;
> +    uint8_t val;
> +    int i;
> +    int64_t cpu_id = -1;
> +
> +    val = cpus->old_sts[addr] ^ data;
> +
> +    if (val == 0) {
> +        return;
> +    }
> +
> +    for (i = 0; i < 8; i++) {
> +        if (val & 1 << i) {
> +            cpu_id = 8 * addr + i;
> +        }
> +    }
> +
> +    if (cpu_id != -1) {
> +        acpi_eject_vcpu(cpus, cpu_id);
> +    }
>  }
>  
>  static const MemoryRegionOps AcpiCpuHotplug_ops = {
> @@ -49,6 +85,7 @@ void AcpiCpuHotplug_handle(ACPIGPE *gpe, AcpiCpuHotplug *g,
>  
>      if (type == PLUG) {
>          g->sts[cpu_id / 8] |= (1 << (cpu_id % 8));
> +        g->old_sts[cpu_id / 8] |= (1 << (cpu_id % 8));
>      } else {
>          g->sts[cpu_id / 8] &= ~(1 << (cpu_id % 8));
>      }
> @@ -65,6 +102,7 @@ void AcpiCpuHotplug_init(MemoryRegion *parent, Object *owner,
>  
>          g_assert((id / 8) < ACPI_GPE_PROC_LEN);
>          gpe_cpu->sts[id / 8] |= (1 << (id % 8));
> +        gpe_cpu->old_sts[id / 8] |= (1 << (id % 8));
>      }
>      memory_region_init_io(&gpe_cpu->io, owner, &AcpiCpuHotplug_ops,
>                            gpe_cpu, "acpi-cpu-hotplug", ACPI_GPE_PROC_LEN);
> diff --git a/hw/i386/acpi-dsdt-cpu-hotplug.dsl b/hw/i386/acpi-dsdt-cpu-hotplug.dsl
> index 34aab5a..9485f12 100644
> --- a/hw/i386/acpi-dsdt-cpu-hotplug.dsl
> +++ b/hw/i386/acpi-dsdt-cpu-hotplug.dsl
> @@ -50,7 +50,11 @@ Scope(\_SB) {
>      }
>      Method(CPEJ, 2, NotSerialized) {
>          // _EJ0 method - eject callback
> -        Sleep(200)
> +        Store(Zero, Index(CPON, ToInteger(Arg0)))
> +        Store(One, Local0)
> +        ShiftLeft(Local0, Arg0, Local0)
> +        Not(Local0, Local0)
> +        And(PRS, Local0, PRS)
>      }
>  
>  #define CPU_STATUS_LEN ACPI_GPE_PROC_LEN
> diff --git a/include/hw/acpi/cpu_hotplug.h b/include/hw/acpi/cpu_hotplug.h
> index 4fe0066..3bffc69 100644
> --- a/include/hw/acpi/cpu_hotplug.h
> +++ b/include/hw/acpi/cpu_hotplug.h
> @@ -28,6 +28,7 @@ typedef struct CPUNotifier {
>  typedef struct AcpiCpuHotplug {
>      MemoryRegion io;
>      uint8_t sts[ACPI_GPE_PROC_LEN];
> +    uint8_t old_sts[ACPI_GPE_PROC_LEN];
>  } AcpiCpuHotplug;
>  
>  void AcpiCpuHotplug_handle(ACPIGPE *gpe, AcpiCpuHotplug *g,
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index 2fc00ef..9108dc6 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -236,6 +236,7 @@ struct CPUState {
>      bool created;
>      bool stop;
>      bool stopped;
> +    bool exit;
>      volatile sig_atomic_t exit_request;
>      uint32_t interrupt_request;
>      int singlestep_enabled;
> @@ -600,6 +601,14 @@ void cpu_exit(CPUState *cpu);
>  void cpu_resume(CPUState *cpu);
>  
>  /**
> + * cpu_remove:
> + * @cpu: The vCPU to remove.
> + *
> + * Requests the CPU @cpu to be removed.
> + */
> +void cpu_remove(CPUState *cpu);
> +
> +/**
>   * qemu_init_vcpu:
>   * @cpu: The vCPU to initialize.
>   *