Re: [PATCH for-5.0 v11 18/20] virtio-iommu: Support migration

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Eric Auger (eric.auger@redhat.com) wrote:
> Add Migration support. We rely on recently added gtree and qlist
> migration. Besides, we have to fixup end point <-> domain link.
> 
> Indeed each domain has a list of endpoints attached to it. And each
> endpoint has a pointer to its domain.
> 
> Raw gtree and qlist migration cannot handle this as it re-allocates
> all the nodes while reconstructing the trees/lists.
> 
> So in post_load we re-construct the relationship between endpoints
> and domains.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>

From the migration side of things,


Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  hw/virtio/virtio-iommu.c | 127 ++++++++++++++++++++++++++++++++++++---
>  1 file changed, 117 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
> index c5b202fab7..4e92fc0c95 100644
> --- a/hw/virtio/virtio-iommu.c
> +++ b/hw/virtio/virtio-iommu.c
> @@ -692,16 +692,6 @@ static void virtio_iommu_set_features(VirtIODevice *vdev, uint64_t val)
>      trace_virtio_iommu_set_features(dev->acked_features);
>  }
>  
> -/*
> - * Migration is not yet supported: most of the state consists
> - * of balanced binary trees which are not yet ready for getting
> - * migrated
> - */
> -static const VMStateDescription vmstate_virtio_iommu_device = {
> -    .name = "virtio-iommu-device",
> -    .unmigratable = 1,
> -};
> -
>  static gint int_cmp(gconstpointer a, gconstpointer b, gpointer user_data)
>  {
>      uint ua = GPOINTER_TO_UINT(a);
> @@ -778,6 +768,123 @@ static void virtio_iommu_instance_init(Object *obj)
>  {
>  }
>  
> +#define VMSTATE_INTERVAL                               \
> +{                                                      \
> +    .name = "interval",                                \
> +    .version_id = 1,                                   \
> +    .minimum_version_id = 1,                           \
> +    .fields = (VMStateField[]) {                       \
> +        VMSTATE_UINT64(low, viommu_interval),          \
> +        VMSTATE_UINT64(high, viommu_interval),         \
> +        VMSTATE_END_OF_LIST()                          \
> +    }                                                  \
> +}
> +
> +#define VMSTATE_MAPPING                               \
> +{                                                     \
> +    .name = "mapping",                                \
> +    .version_id = 1,                                  \
> +    .minimum_version_id = 1,                          \
> +    .fields = (VMStateField[]) {                      \
> +        VMSTATE_UINT64(phys_addr, viommu_mapping),    \
> +        VMSTATE_UINT32(flags, viommu_mapping),        \
> +        VMSTATE_END_OF_LIST()                         \
> +    },                                                \
> +}
> +
> +static const VMStateDescription vmstate_interval_mapping[2] = {
> +    VMSTATE_MAPPING,   /* value */
> +    VMSTATE_INTERVAL   /* key   */
> +};
> +
> +static int domain_preload(void *opaque)
> +{
> +    viommu_domain *domain = opaque;
> +
> +    domain->mappings = g_tree_new_full((GCompareDataFunc)interval_cmp,
> +                                       NULL, g_free, g_free);
> +    return 0;
> +}
> +
> +static const VMStateDescription vmstate_endpoint = {
> +    .name = "endpoint",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT32(id, viommu_endpoint),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static const VMStateDescription vmstate_domain = {
> +    .name = "domain",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .pre_load = domain_preload,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT32(id, viommu_domain),
> +        VMSTATE_GTREE_V(mappings, viommu_domain, 1,
> +                        vmstate_interval_mapping,
> +                        viommu_interval, viommu_mapping),
> +        VMSTATE_QLIST_V(endpoint_list, viommu_domain, 1,
> +                        vmstate_endpoint, viommu_endpoint, next),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static gboolean reconstruct_ep_domain_link(gpointer key, gpointer value,
> +                                           gpointer data)
> +{
> +    viommu_domain *d = (viommu_domain *)value;
> +    viommu_endpoint *iter, *tmp;
> +    viommu_endpoint *ep = (viommu_endpoint *)data;
> +
> +    QLIST_FOREACH_SAFE(iter, &d->endpoint_list, next, tmp) {
> +        if (iter->id == ep->id) {
> +            /* remove the ep */
> +            QLIST_REMOVE(iter, next);
> +            g_free(iter);
> +            /* replace it with the good one */
> +            QLIST_INSERT_HEAD(&d->endpoint_list, ep, next);
> +            /* update the domain */
> +            ep->domain = d;
> +            return true; /* stop the search */
> +        }
> +    }
> +    return false; /* continue the traversal */
> +}
> +
> +static gboolean fix_endpoint(gpointer key, gpointer value, gpointer data)
> +{
> +    VirtIOIOMMU *s = (VirtIOIOMMU *)data;
> +
> +    g_tree_foreach(s->domains, reconstruct_ep_domain_link, value);
> +    return false;
> +}
> +
> +static int iommu_post_load(void *opaque, int version_id)
> +{
> +    VirtIOIOMMU *s = opaque;
> +
> +    g_tree_foreach(s->endpoints, fix_endpoint, s);
> +    return 0;
> +}
> +
> +static const VMStateDescription vmstate_virtio_iommu_device = {
> +    .name = "virtio-iommu-device",
> +    .minimum_version_id = 1,
> +    .version_id = 1,
> +    .post_load = iommu_post_load,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_GTREE_DIRECT_KEY_V(domains, VirtIOIOMMU, 1,
> +                                   &vmstate_domain, viommu_domain),
> +        VMSTATE_GTREE_DIRECT_KEY_V(endpoints, VirtIOIOMMU, 1,
> +                                   &vmstate_endpoint, viommu_endpoint),
> +        VMSTATE_END_OF_LIST()
> +    },
> +};
> +
> +
>  static const VMStateDescription vmstate_virtio_iommu = {
>      .name = "virtio-iommu",
>      .minimum_version_id = 1,
> -- 
> 2.20.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK