Re: [Xen-devel] [PATCH v2 3/8] xen: delay allocation of grant table sub structures

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of
> Juergen Gross
> Sent: 06 September 2017 09:26
> To: xen-devel@xxxxxxxxxxxxx
> Cc: Juergen Gross <jgross@xxxxxxxx>; sstabellini@xxxxxxxxxx; Wei Liu
> <wei.liu2@xxxxxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxx>;
> Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Ian Jackson
> <Ian.Jackson@xxxxxxxxxx>; Tim (Xen.org) <tim@xxxxxxx>;
> jbeulich@xxxxxxxx
> Subject: [Xen-devel] [PATCH v2 3/8] xen: delay allocation of grant table sub
> structures
> 
> Delay the allocation of the grant table sub structures in order to
> allow modifying parameters needed for sizing of these structures at a
> per domain basis. Either do it from gnttab_setup_table() or just
> before the domain is started the first time.

Why does it need to be in two places? Could it not just be done on the first 
call to gnttab_grow_table()?

(My new direct mapping series drops the call to gnttab_setup_table() if the new 
API is available).

  Paul

> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
>  xen/common/domain.c           |  17 +++++-
>  xen/common/grant_table.c      | 139 ++++++++++++++++++++++++----------
> --------
>  xen/include/xen/grant_table.h |   2 +
>  3 files changed, 97 insertions(+), 61 deletions(-)
> 
> diff --git a/xen/common/domain.c b/xen/common/domain.c
> index 5aebcf265f..11eb1778a3 100644
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -363,6 +363,9 @@ struct domain *domain_create(domid_t domid,
> unsigned int domcr_flags,
>              goto fail;
>          init_status |= INIT_gnttab;
> 
> +        if ( domid == 0 && grant_table_init(d) )
> +            goto fail;
> +
>          poolid = 0;
> 
>          err = -ENOMEM;
> @@ -998,7 +1001,8 @@ int __domain_pause_by_systemcontroller(struct
> domain *d,
>          prev = cmpxchg(&d->controller_pause_count, old, new);
>      } while ( prev != old );
> 
> -    pause_fn(d);
> +    if ( pause_fn )
> +        pause_fn(d);
> 
>      return 0;
>  }
> @@ -1006,6 +1010,7 @@ int __domain_pause_by_systemcontroller(struct
> domain *d,
>  int domain_unpause_by_systemcontroller(struct domain *d)
>  {
>      int old, new, prev = d->controller_pause_count;
> +    int ret;
> 
>      do
>      {
> @@ -1029,8 +1034,16 @@ int domain_unpause_by_systemcontroller(struct
> domain *d)
>       * Creation is considered finished when the controller reference count
>       * first drops to 0.
>       */
> -    if ( new == 0 )
> +    if ( new == 0 && !d->creation_finished )
> +    {
> +        ret = grant_table_init(d);
> +        if ( ret )
> +        {
> +            __domain_pause_by_systemcontroller(d, NULL);
> +            return ret;
> +        }
>          d->creation_finished = true;
> +    }
> 
>      domain_unpause(d);
> 
> diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
> index a94dfdda7b..b50c334f70 100644
> --- a/xen/common/grant_table.c
> +++ b/xen/common/grant_table.c
> @@ -1719,6 +1719,78 @@ active_alloc_failed:
>      return 0;
>  }
> 
> +int
> +grant_table_init(struct domain *d)
> +{
> +    struct grant_table *gt = d->grant_table;
> +    unsigned int i, j;
> +
> +    if ( gt->nr_grant_frames )
> +        return 0;
> +
> +    gt->nr_grant_frames = INITIAL_NR_GRANT_FRAMES;
> +
> +    /* Active grant table. */
> +    if ( (gt->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 ( (gt->active[i] = alloc_xenheap_page()) == NULL )
> +            goto no_mem_2;
> +        clear_page(gt->active[i]);
> +        for ( j = 0; j < ACGNT_PER_PAGE; j++ )
> +            spin_lock_init(&gt->active[i][j].lock);
> +    }
> +
> +    /* Tracking of mapped foreign frames table */
> +    gt->maptrack = vzalloc(max_maptrack_frames * sizeof(*gt->maptrack));
> +    if ( gt->maptrack == NULL )
> +        goto no_mem_2;
> +
> +    /* Shared grant table. */
> +    if ( (gt->shared_raw = xzalloc_array(void *, max_grant_frames)) == NULL
> )
> +        goto no_mem_3;
> +    for ( i = 0; i < INITIAL_NR_GRANT_FRAMES; i++ )
> +    {
> +        if ( (gt->shared_raw[i] = alloc_xenheap_page()) == NULL )
> +            goto no_mem_4;
> +        clear_page(gt->shared_raw[i]);
> +    }
> +
> +    /* Status pages for grant table - for version 2 */
> +    gt->status = xzalloc_array(grant_status_t *,
> +                               grant_to_status_frames(max_grant_frames));
> +    if ( gt->status == NULL )
> +        goto no_mem_4;
> +
> +    for ( i = 0; i < INITIAL_NR_GRANT_FRAMES; i++ )
> +        gnttab_create_shared_page(d, gt, i);
> +
> +    gt->nr_status_frames = 0;
> +
> +    return 0;
> +
> + no_mem_4:
> +    for ( i = 0; i < INITIAL_NR_GRANT_FRAMES; i++ )
> +        free_xenheap_page(gt->shared_raw[i]);
> +    xfree(gt->shared_raw);
> +    gt->shared_raw = NULL;
> + no_mem_3:
> +    vfree(gt->maptrack);
> +    gt->maptrack = NULL;
> + no_mem_2:
> +    for ( i = 0;
> +          i <
> num_act_frames_from_sha_frames(INITIAL_NR_GRANT_FRAMES); i++ )
> +        free_xenheap_page(gt->active[i]);
> +    xfree(gt->active);
> +    gt->active = NULL;
> + no_mem_1:
> +    gt->nr_grant_frames = 0;
> +    return -ENOMEM;
> +}
> +
>  static long
>  gnttab_setup_table(
>      XEN_GUEST_HANDLE_PARAM(gnttab_setup_table_t) uop, unsigned int
> count)
> @@ -1764,7 +1836,14 @@ gnttab_setup_table(
>      grant_write_lock(gt);
> 
>      if ( gt->gt_version == 0 )
> +    {
> +        if ( grant_table_init(d) )
> +        {
> +            op.status = GNTST_general_error;
> +            goto unlock;
> +        }
>          gt->gt_version = 1;
> +    }
> 
>      if ( (op.nr_frames > nr_grant_frames(gt) ||
>            ((gt->gt_version > 1) &&
> @@ -3378,75 +3457,17 @@ 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;
>  }
> 
>  void
> diff --git a/xen/include/xen/grant_table.h b/xen/include/xen/grant_table.h
> index 43b07e60c5..84a8d61616 100644
> --- a/xen/include/xen/grant_table.h
> +++ b/xen/include/xen/grant_table.h
> @@ -35,6 +35,8 @@ extern unsigned int max_grant_frames;
>  /* Create/destroy per-domain grant table context. */
>  int grant_table_create(
>      struct domain *d);
> +int grant_table_init(
> +    struct domain *d);
>  void grant_table_destroy(
>      struct domain *d);
>  void grant_table_init_vcpu(struct vcpu *v);
> --
> 2.12.3
> 
> 
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