[v9,QEMU,07/15] vfio: Add migration region initialization and finalize function

- Migration functions are implemented for VFIO_DEVICE_TYPE_PCI device in this
  patch series.
- VFIO device supports migration or not is decided based of migration region
  query. If migration region query is successful and migration region
  initialization is successful then migration is supported else migration is
  blocked.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
 hw/vfio/Makefile.objs         |   2 +-
 hw/vfio/migration.c           | 137 ++++++++++++++++++++++++++++++++++++++++++
 hw/vfio/trace-events          |   3 +
 include/hw/vfio/vfio-common.h |  10 +++
 4 files changed, 151 insertions(+), 1 deletion(-)
 create mode 100644 hw/vfio/migration.c

On Tue, 12 Nov 2019 22:35:16 +0530
Kirti Wankhede <kwankhede@nvidia.com> wrote:

> - Migration functions are implemented for VFIO_DEVICE_TYPE_PCI device in this
>   patch series.
> - VFIO device supports migration or not is decided based of migration region
>   query. If migration region query is successful and migration region
>   initialization is successful then migration is supported else migration is
>   blocked.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> Reviewed-by: Neo Jia <cjia@nvidia.com>
> ---
>  hw/vfio/Makefile.objs         |   2 +-
>  hw/vfio/migration.c           | 137 ++++++++++++++++++++++++++++++++++++++++++
>  hw/vfio/trace-events          |   3 +
>  include/hw/vfio/vfio-common.h |  10 +++
>  4 files changed, 151 insertions(+), 1 deletion(-)
>  create mode 100644 hw/vfio/migration.c
> 
> diff --git a/hw/vfio/Makefile.objs b/hw/vfio/Makefile.objs
> index abad8b818c9b..36033d1437c5 100644
> --- a/hw/vfio/Makefile.objs
> +++ b/hw/vfio/Makefile.objs
> @@ -1,4 +1,4 @@
> -obj-y += common.o spapr.o
> +obj-y += common.o spapr.o migration.o
>  obj-$(CONFIG_VFIO_PCI) += pci.o pci-quirks.o display.o
>  obj-$(CONFIG_VFIO_CCW) += ccw.o
>  obj-$(CONFIG_VFIO_PLATFORM) += platform.o
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> new file mode 100644
> index 000000000000..c17bd1b0b934
> --- /dev/null
> +++ b/hw/vfio/migration.c
> @@ -0,0 +1,137 @@
> +/*
> + * Migration support for VFIO devices
> + *
> + * Copyright NVIDIA, Inc. 2019
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2. See
> + * the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include <linux/vfio.h>
> +
> +#include "hw/vfio/vfio-common.h"
> +#include "cpu.h"
> +#include "migration/migration.h"
> +#include "migration/qemu-file.h"
> +#include "migration/register.h"
> +#include "migration/blocker.h"
> +#include "migration/misc.h"
> +#include "qapi/error.h"
> +#include "exec/ramlist.h"
> +#include "exec/ram_addr.h"
> +#include "pci.h"
> +#include "trace.h"
> +
> +static void vfio_migration_region_exit(VFIODevice *vbasedev)
> +{
> +    VFIOMigration *migration = vbasedev->migration;
> +
> +    if (!migration) {
> +        return;
> +    }
> +
> +    if (migration->region.size) {
> +        vfio_region_exit(&migration->region);
> +        vfio_region_finalize(&migration->region);
> +    }
> +}
> +
> +static int vfio_migration_region_init(VFIODevice *vbasedev, int index)
> +{
> +    VFIOMigration *migration = vbasedev->migration;
> +    Object *obj = NULL;
> +    int ret = -EINVAL;
> +
> +    if (!vbasedev->ops || !vbasedev->ops->vfio_get_object) {

Is it possible not to have vbasedev->ops?

> +        return ret;
> +    }
> +
> +    obj = vbasedev->ops->vfio_get_object(vbasedev);
> +    if (!obj) {
> +        return ret;
> +    }
> +
> +    ret = vfio_region_setup(obj, vbasedev, &migration->region, index,
> +                            "migration");
> +    if (ret) {
> +        error_report("%s: Failed to setup VFIO migration region %d: %s",
> +                     vbasedev->name, index, strerror(-ret));
> +        goto err;
> +    }
> +
> +    if (!migration->region.size) {
> +        ret = -EINVAL;
> +        error_report("%s: Invalid region size of VFIO migration region %d: %s",
> +                     vbasedev->name, index, strerror(-ret));
> +        goto err;
> +    }
> +
> +    return 0;
> +
> +err:
> +    vfio_migration_region_exit(vbasedev);
> +    return ret;
> +}
> +
> +static int vfio_migration_init(VFIODevice *vbasedev,
> +                               struct vfio_region_info *info)
> +{
> +    int ret;
> +
> +    vbasedev->migration = g_new0(VFIOMigration, 1);
> +
> +    ret = vfio_migration_region_init(vbasedev, info->index);
> +    if (ret) {
> +        error_report("%s: Failed to initialise migration region",
> +                     vbasedev->name);
> +        g_free(vbasedev->migration);

Note that vbasedev->migration is not NULL, so calling
vfio_migration_region_exit() at this point will be a use-after-free
error.

> +        return ret;
> +    }
> +
> +    return 0;
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +
> +int vfio_migration_probe(VFIODevice *vbasedev, Error **errp)
> +{
> +    struct vfio_region_info *info;
> +    Error *local_err = NULL;
> +    int ret;
> +
> +    ret = vfio_get_dev_region_info(vbasedev, VFIO_REGION_TYPE_MIGRATION,
> +                                   VFIO_REGION_SUBTYPE_MIGRATION, &info);
> +    if (ret) {
> +        goto add_blocker;
> +    }
> +
> +    ret = vfio_migration_init(vbasedev, info);
> +    if (ret) {
> +        goto add_blocker;
> +    }
> +
> +    trace_vfio_migration_probe(vbasedev->name, info->index);
> +    return 0;
> +
> +add_blocker:
> +    error_setg(&vbasedev->migration_blocker,
> +               "VFIO device doesn't support migration");
> +    ret = migrate_add_blocker(vbasedev->migration_blocker, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        error_free(vbasedev->migration_blocker);
> +    }

This won't get along well with the failover code that's in QEMU master.

> +    return ret;
> +}
> +
> +void vfio_migration_finalize(VFIODevice *vbasedev)
> +{
> +    if (vbasedev->migration_blocker) {
> +        migrate_del_blocker(vbasedev->migration_blocker);
> +        error_free(vbasedev->migration_blocker);
> +    }
> +
> +    vfio_migration_region_exit(vbasedev);
> +    g_free(vbasedev->migration);

This will do bad things if vfio_migration_init() failed as indicated
above.

> +}
> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
> index 8cdc27946cb8..191a726a1312 100644
> --- a/hw/vfio/trace-events
> +++ b/hw/vfio/trace-events
> @@ -143,3 +143,6 @@ vfio_display_edid_link_up(void) ""
>  vfio_display_edid_link_down(void) ""
>  vfio_display_edid_update(uint32_t prefx, uint32_t prefy) "%ux%u"
>  vfio_display_edid_write_error(void) ""
> +
> +# migration.c
> +vfio_migration_probe(char *name, uint32_t index) " (%s) Region %d"
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index d69a7f3ae31e..927511897a44 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -57,6 +57,11 @@ typedef struct VFIORegion {
>      uint8_t nr; /* cache the region number for debug */
>  } VFIORegion;
>  
> +typedef struct VFIOMigration {
> +    VFIORegion region;
> +    uint64_t pending_bytes;

pending_bytes is not used here, let's add it when it's needed.

> +} VFIOMigration;
> +
>  typedef struct VFIOAddressSpace {
>      AddressSpace *as;
>      QLIST_HEAD(, VFIOContainer) containers;
> @@ -113,6 +118,8 @@ typedef struct VFIODevice {
>      unsigned int num_irqs;
>      unsigned int num_regions;
>      unsigned int flags;
> +    VFIOMigration *migration;
> +    Error *migration_blocker;

See:

f045a0104c8c ("vfio: unplug failover primary device before migration")

Edit: I see once I got to the last patch how you managed this.

>  } VFIODevice;
>  
>  struct VFIODeviceOps {
> @@ -204,4 +211,7 @@ int vfio_spapr_create_window(VFIOContainer *container,
>  int vfio_spapr_remove_window(VFIOContainer *container,
>                               hwaddr offset_within_address_space);
>  
> +int vfio_migration_probe(VFIODevice *vbasedev, Error **errp);
> +void vfio_migration_finalize(VFIODevice *vbasedev);
> +
>  #endif /* HW_VFIO_VFIO_COMMON_H */