Re: [Qemu-devel] [PATCH v7 08/13] vfio: Register SaveVMHandlers for VFIO device

[Kirti Wankhede <kwankhede@nvidia.com>]

On 7/22/2019 2:04 PM, Yan Zhao wrote:
> On Tue, Jul 09, 2019 at 05:49:15PM +0800, Kirti Wankhede wrote:
>> Define flags to be used as delimeter in migration file stream.
>> Added .save_setup and .save_cleanup functions. Mapped & unmapped migration
>> region from these functions at source during saving or pre-copy phase.
>> Set VFIO device state depending on VM's state. During live migration, VM is
>> running when .save_setup is called, _SAVING | _RUNNING state is set for VFIO
>> device. During save-restore, VM is paused, _SAVING state is set for VFIO device.
>>
>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>> ---
>>  hw/vfio/migration.c  | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>>  hw/vfio/trace-events |  2 ++
>>  2 files changed, 83 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
>> index e4a89a6f9bc7..0597a45fda2d 100644
>> --- a/hw/vfio/migration.c
>> +++ b/hw/vfio/migration.c
>> @@ -23,6 +23,17 @@
>>  #include "pci.h"
>>  #include "trace.h"
>>  
>> +/*
>> + * Flags used as delimiter:
>> + * 0xffffffff => MSB 32-bit all 1s
>> + * 0xef10     => emulated (virtual) function IO
>> + * 0x0000     => 16-bits reserved for flags
>> + */
>> +#define VFIO_MIG_FLAG_END_OF_STATE      (0xffffffffef100001ULL)
>> +#define VFIO_MIG_FLAG_DEV_CONFIG_STATE  (0xffffffffef100002ULL)
>> +#define VFIO_MIG_FLAG_DEV_SETUP_STATE   (0xffffffffef100003ULL)
>> +#define VFIO_MIG_FLAG_DEV_DATA_STATE    (0xffffffffef100004ULL)
>> +
>>  static void vfio_migration_region_exit(VFIODevice *vbasedev)
>>  {
>>      VFIOMigration *migration = vbasedev->migration;
>> @@ -106,6 +117,74 @@ static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t state)
>>      return 0;
>>  }
>>  
>> +/* ---------------------------------------------------------------------- */
>> +
>> +static int vfio_save_setup(QEMUFile *f, void *opaque)
>> +{
>> +    VFIODevice *vbasedev = opaque;
>> +    VFIOMigration *migration = vbasedev->migration;
>> +    int ret;
>> +
>> +    qemu_put_be64(f, VFIO_MIG_FLAG_DEV_SETUP_STATE);
>> +
>> +    if (migration->region.buffer.mmaps) {
>> +        qemu_mutex_lock_iothread();
>> +        ret = vfio_region_mmap(&migration->region.buffer);
>> +        qemu_mutex_unlock_iothread();
>> +        if (ret) {
>> +            error_report("%s: Failed to mmap VFIO migration region %d: %s",
>> +                         vbasedev->name, migration->region.index,
>> +                         strerror(-ret));
>> +            return ret;
>> +        }
>> +    }
>> +
>> +    if (vbasedev->vm_running) {
>> +        ret = vfio_migration_set_state(vbasedev,
>> +                         VFIO_DEVICE_STATE_RUNNING | VFIO_DEVICE_STATE_SAVING);
>> +        if (ret) {
>> +            error_report("%s: Failed to set state RUNNING and SAVING",
>> +                         vbasedev->name);
>> +            return ret;
>> +        }
>> +    } else {
> hi Kirti
> May I know in which condition will this "else" case happen?
> 

This can happen in savevm case.

Thanks,
Kirti

> Thanks
> Yan
> 
>> +        ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_SAVING);
>> +        if (ret) {
>> +            error_report("%s: Failed to set state STOP and SAVING",
>> +                         vbasedev->name);
>> +            return ret;
>> +        }
>> +    }
>> +
>> +    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
>> +
>> +    ret = qemu_file_get_error(f);
>> +    if (ret) {
>> +        return ret;
>> +    }
>> +
>> +    trace_vfio_save_setup(vbasedev->name);
>> +    return 0;
>> +}
>> +
>> +static void vfio_save_cleanup(void *opaque)
>> +{
>> +    VFIODevice *vbasedev = opaque;
>> +    VFIOMigration *migration = vbasedev->migration;
>> +
>> +    if (migration->region.buffer.mmaps) {
>> +        vfio_region_unmap(&migration->region.buffer);
>> +    }
>> +    trace_vfio_save_cleanup(vbasedev->name);
>> +}
>> +
>> +static SaveVMHandlers savevm_vfio_handlers = {
>> +    .save_setup = vfio_save_setup,
>> +    .save_cleanup = vfio_save_cleanup,
>> +};
>> +
>> +/* ---------------------------------------------------------------------- */
>> +
>>  static void vfio_vmstate_change(void *opaque, int running, RunState state)
>>  {
>>      VFIODevice *vbasedev = opaque;
>> @@ -195,7 +274,8 @@ static int vfio_migration_init(VFIODevice *vbasedev,
>>      }
>>  
>>      qemu_mutex_init(&vbasedev->migration->lock);
>> -
>> +    register_savevm_live(vbasedev->dev, "vfio", -1, 1, &savevm_vfio_handlers,
>> +                         vbasedev);
>>      vbasedev->vm_state = qemu_add_vm_change_state_handler(vfio_vmstate_change,
>>                                                            vbasedev);
>>  
>> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
>> index 69503228f20e..4bb43f18f315 100644
>> --- a/hw/vfio/trace-events
>> +++ b/hw/vfio/trace-events
>> @@ -149,3 +149,5 @@ vfio_migration_probe(char *name, uint32_t index) " (%s) Region %d"
>>  vfio_migration_set_state(char *name, uint32_t state) " (%s) state %d"
>>  vfio_vmstate_change(char *name, int running, const char *reason, uint32_t dev_state) " (%s) running %d reason %s device state %d"
>>  vfio_migration_state_notifier(char *name, int state) " (%s) state %d"
>> +vfio_save_setup(char *name) " (%s)"
>> +vfio_save_cleanup(char *name) " (%s)"
>> -- 
>> 2.7.0
>>