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

[Yan Zhao]

On Wed, Aug 21, 2019 at 04:33:06AM +0800, Kirti Wankhede wrote:
> 
> 
> 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 <address@hidden>
> >> Reviewed-by: Neo Jia <address@hidden>
> >> ---
> >>  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.

ok. I see it. thanks.
Could we simplify the logic and only or VFIO_DEVICE_STATE_SAVING to
current device state here?
Because device state was already set to RUNNING or STOP in
vfio_vmstate_change().

Thanks
Yan
> 
> 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
> >>