Re: [PATCH V2 4/6] cpr: relax vhost migration blockers

[Peter Xu]

Copy qemu-block, virtio

On Wed, Oct 25, 2023 at 12:44:27PM -0700, Steve Sistare wrote:
> vhost blocks migration if logging is not supported to track dirty
> memory, and vhost-user blocks it if the log cannot be saved to a shm fd.
> 
> vhost-vdpa blocks migration if both hosts do not support all the device's
> features using a shadow VQ, for tracking requests and dirty memory.
> 
> vhost-scsi blocks migration if storage cannot be shared across hosts,
> or if state cannot be migrated.
> 
> None of these conditions apply if the old and new qemu processes do
> not run concurrently, and if new qemu starts on the same host as old,
> which is the case for cpr.
> 
> Narrow the scope of these blockers so they only apply to normal mode.
> They will not block cpr modes when they are added in subsequent patches.
> 
> No functional change until a new mode is added.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> Reviewed-by: Juan Quintela <quintela@redhat.com>
> ---
>  hw/scsi/vhost-scsi.c | 2 +-
>  hw/virtio/vhost.c    | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
> index 14e23cc..bf528d5 100644
> --- a/hw/scsi/vhost-scsi.c
> +++ b/hw/scsi/vhost-scsi.c
> @@ -208,7 +208,7 @@ static void vhost_scsi_realize(DeviceState *dev, Error 
> **errp)
>                  "When external environment supports it (Orchestrator 
> migrates "
>                  "target SCSI device state or use shared storage over 
> network), "
>                  "set 'migratable' property to true to enable migration.");
> -        if (migrate_add_blocker(&vsc->migration_blocker, errp) < 0) {
> +        if (migrate_add_blocker_normal(&vsc->migration_blocker, errp) < 0) {
>              goto free_virtio;
>          }
>      }
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index d737671..f5e9625 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1527,7 +1527,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
>      }
>  
>      if (hdev->migration_blocker != NULL) {
> -        r = migrate_add_blocker(&hdev->migration_blocker, errp);
> +        r = migrate_add_blocker_normal(&hdev->migration_blocker, errp);
>          if (r < 0) {
>              goto fail_busyloop;
>          }
> -- 
> 1.8.3.1
> 

-- 
Peter Xu