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

[Juergen Gross <jgross@xxxxxxxx>]

On 20/09/17 11:22, Jan Beulich wrote:
>>>> 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.

So you don't like gnttab_grow_table() being called when the guest tries
to map the grant frames in this case?

I can add the call of gnttab_grow_table() to grant_table_set_limits() in
case you like that better.


Juergen


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