Re: [Xen-devel] [PATCH v8 11/15] xen: delay allocation of grant table sub structures

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.09.17 at 08:34, <jgross@xxxxxxxx> wrote:
> @@ -3381,75 +3425,21 @@ grant_table_create(
>      struct domain *d)
>  {
>      struct grant_table *t;
> -    unsigned int i, j;
>  
>      if ( (t = xzalloc(struct grant_table)) == NULL )
> -        goto no_mem_0;
> +        return -ENOMEM;
>  
>      /* Simple stuff. */
>      percpu_rwlock_resource_init(&t->lock, grant_rwlock);
>      spin_lock_init(&t->maptrack_lock);
> -    t->nr_grant_frames = INITIAL_NR_GRANT_FRAMES;
> -
> -    /* Active grant table. */
> -    if ( (t->active = xzalloc_array(struct active_grant_entry *,
> -                                    max_nr_active_grant_frames)) == NULL )
> -        goto no_mem_1;
> -    for ( i = 0;
> -          i < num_act_frames_from_sha_frames(INITIAL_NR_GRANT_FRAMES); i++ )
> -    {
> -        if ( (t->active[i] = alloc_xenheap_page()) == NULL )
> -            goto no_mem_2;
> -        clear_page(t->active[i]);
> -        for ( j = 0; j < ACGNT_PER_PAGE; j++ )
> -            spin_lock_init(&t->active[i][j].lock);
> -    }
> -
> -    /* Tracking of mapped foreign frames table */
> -    t->maptrack = vzalloc(max_maptrack_frames * sizeof(*t->maptrack));
> -    if ( t->maptrack == NULL )
> -        goto no_mem_2;
> -
> -    /* Shared grant table. */
> -    if ( (t->shared_raw = xzalloc_array(void *, max_grant_frames)) == NULL )
> -        goto no_mem_3;
> -    for ( i = 0; i < INITIAL_NR_GRANT_FRAMES; i++ )
> -    {
> -        if ( (t->shared_raw[i] = alloc_xenheap_page()) == NULL )
> -            goto no_mem_4;
> -        clear_page(t->shared_raw[i]);
> -    }
> -
> -    /* Status pages for grant table - for version 2 */
> -    t->status = xzalloc_array(grant_status_t *,
> -                              grant_to_status_frames(max_grant_frames));
> -    if ( t->status == NULL )
> -        goto no_mem_4;
> -
> -    for ( i = 0; i < INITIAL_NR_GRANT_FRAMES; i++ )
> -        gnttab_create_shared_page(d, t, i);
> -
> -    t->nr_status_frames = 0;
>  
>      /* Okay, install the structure. */
>      d->grant_table = t;
> -    return 0;
>  
> - no_mem_4:
> -    for ( i = 0; i < INITIAL_NR_GRANT_FRAMES; i++ )
> -        free_xenheap_page(t->shared_raw[i]);
> -    xfree(t->shared_raw);
> - no_mem_3:
> -    vfree(t->maptrack);
> - no_mem_2:
> -    for ( i = 0;
> -          i < num_act_frames_from_sha_frames(INITIAL_NR_GRANT_FRAMES); i++ )
> -        free_xenheap_page(t->active[i]);
> -    xfree(t->active);
> - no_mem_1:
> -    xfree(t);
> - no_mem_0:
> -    return -ENOMEM;
> +    if ( d->domain_id == 0 )
> +        return grant_table_init(t);
> +
> +    return 0;
>  }
>  
>  void
> @@ -3651,8 +3641,9 @@ int grant_table_set_limits(struct domain *d, unsigned 
> int grant_frames,
>  
>      grant_write_lock(gt);
>  
> -    ret = 0;
> -    /* Set limits, alloc needed arrays. */
> +    /* Set limits. */
> +    if ( !gt->active )
> +        ret = grant_table_init(gt);
>  
>      grant_write_unlock(gt);

These changes don't leave the domains in a state similar to that
before the change - I'm missing calls to gnttab_grow_table() to
establish the minimal sizes. Aiui so far there has been no
requirement for a domain to invoke GNTTABOP_setup_table if it
is happy with v1 and the minimum size.

Jan


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