Re: [PATCH v4 12/14] vfio/migration: Block migration with vIOMMU

[Cédric Le Goater]

On 3/7/23 03:02, Joao Martins wrote:
> Migrating with vIOMMU will require either tracking maximum
> IOMMU supported address space (e.g. 39/48 address width on Intel)
> or range-track current mappings and dirty track the new ones
> post starting dirty tracking. This will be done as a separate
> series, so add a live migration blocker until that is fixed.
>
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>

Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.


> ---
>   hw/vfio/common.c              | 46 +++++++++++++++++++++++++++++++++++
>   hw/vfio/migration.c           |  5 ++++
>   hw/vfio/pci.c                 |  1 +
>   include/hw/vfio/vfio-common.h |  2 ++
>   4 files changed, 54 insertions(+)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 75b4902bbcc9..7278baa82f7d 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -362,6 +362,7 @@ bool vfio_mig_active(void)
>   }
>   
>   static Error *multiple_devices_migration_blocker;
> +static Error *giommu_migration_blocker;
>   
>   static unsigned int vfio_migratable_device_num(void)
>   {
> @@ -413,6 +414,51 @@ void vfio_unblock_multiple_devices_migration(void)
>       multiple_devices_migration_blocker = NULL;
>   }
>   
> +static bool vfio_viommu_preset(void)
> +{
> +    VFIOAddressSpace *space;
> +
> +    QLIST_FOREACH(space, &vfio_address_spaces, list) {
> +        if (space->as != &address_space_memory) {
> +            return true;
> +        }
> +    }
> +
> +    return false;
> +}
> +
> +int vfio_block_giommu_migration(Error **errp)
> +{
> +    int ret;
> +
> +    if (giommu_migration_blocker ||
> +        !vfio_viommu_preset()) {
> +        return 0;
> +    }
> +
> +    error_setg(&giommu_migration_blocker,
> +               "Migration is currently not supported with vIOMMU enabled");
> +    ret = migrate_add_blocker(giommu_migration_blocker, errp);
> +    if (ret < 0) {
> +        error_free(giommu_migration_blocker);
> +        giommu_migration_blocker = NULL;
> +    }
> +
> +    return ret;
> +}
> +
> +void vfio_unblock_giommu_migration(void)
> +{
> +    if (!giommu_migration_blocker ||
> +        vfio_viommu_preset()) {
> +        return;
> +    }
> +
> +    migrate_del_blocker(giommu_migration_blocker);
> +    error_free(giommu_migration_blocker);
> +    giommu_migration_blocker = NULL;
> +}
> +
>   static void vfio_set_migration_error(int err)
>   {
>       MigrationState *ms = migrate_get_current();
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index a2c3d9bade7f..776fd2d7cdf3 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -634,6 +634,11 @@ int vfio_migration_probe(VFIODevice *vbasedev, Error 
> **errp)
>           return ret;
>       }
>   
> +    ret = vfio_block_giommu_migration(errp);
> +    if (ret) {
> +        return ret;
> +    }
> +
>       trace_vfio_migration_probe(vbasedev->name);
>       return 0;
>   
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 939dcc3d4a9e..30a271eab38c 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -3185,6 +3185,7 @@ static void vfio_instance_finalize(Object *obj)
>        */
>       vfio_put_device(vdev);
>       vfio_put_group(group);
> +    vfio_unblock_giommu_migration();
>   }
>   
>   static void vfio_exitfn(PCIDevice *pdev)
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 7817ca7d8706..63f93ab54811 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -235,6 +235,8 @@ extern VFIOGroupList vfio_group_list;
>   bool vfio_mig_active(void);
>   int vfio_block_multiple_devices_migration(Error **errp);
>   void vfio_unblock_multiple_devices_migration(void);
> +int vfio_block_giommu_migration(Error **errp);
> +void vfio_unblock_giommu_migration(void);
>   int64_t vfio_mig_bytes_transferred(void);
>   
>   #ifdef CONFIG_LINUX