Re: [Xen-devel] [v5][PATCH 09/10] tools:firmware:hvmloader: check to reserve RMRR mappings in e820

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

On 2014/9/2 16:47, Jan Beulich wrote:
> > > > On 26.08.14 at 13:02, <tiejun.chen@xxxxxxxxx> wrote:
> > +static unsigned int construct_rmrr_e820_maps(unsigned int nr,
s/construct_rmrr_e820_maps/construct_drm_e820_maps

> > +                                             uint32_t nr_map,
> > +                                             struct reserved_device_memory 
> > *map,
> > +                                             struct e820entry *e820)
> > +{
> > +    unsigned int i = 0, j = 0, m = 0, sum_nr = 0;
> > +    uint64_t start, end, rmrr_start, rmrr_end;
I rename this pair of variables in this whole function,

s/rmrr_start/drm_start
s/rmrr_end/drm_end

> > +    unsigned int insert = 0, do_insert = 0;
> > +
> > +do_real_construct:
> Please indent labels by at least one space (and there are further
> coding style issues to address elsewhere).
Is this necessary?

static struct tmem_object_root * obj_find(struct tmem_pool *pool, struct 
oid *oidp)
{
    struct rb_node *node;
    struct tmem_object_root *obj;

restart_find:
    read_lock(&pool->pool_rwlock);
    ...
                    read_unlock(&pool->pool_rwlock);
                    goto restart_find;

> > +    sum_nr = nr + nr_map;
> Afaict neither nr nor nr_map change before you get here the second
> (and last) time. Hence the calculation can be moved up (ideally into
> the initializer of the variable).
+    unsigned int i = 0, j = 0, m = 0, sum_nr = nr + nr_map;

> > +    for ( i = 0; i < nr_map; i++ )
> > +    {
> > +        rmrr_start = map[i].start_pfn << PAGE_SHIFT;
> > +        rmrr_end = rmrr_start + map[i].nr_pages * PAGE_SIZE;
> > +
> > +        for ( j = 0; j < nr; j++ )
> > +        {
> > +            end = e820[j].addr + e820[j].size;
> > +            start = e820[j+1].addr;
> This is not valid when j == nr - 1 (last iteration).
-        for ( j = 0; j < nr; j++ )
+        for ( j = 0; j < nr - 1; j++ )

> > +
> > +            /* Between those existing e820 entries. */
> > +            if ( (rmrr_start > end) && (rmrr_end < start) )
> > +            {
> > +                if (do_insert)
-                if (do_insert)
+                if ( do_insert )

> > +                {
> > +                    /* Move to free this entry. */
> > +                    for ( m = sum_nr - 1; m > j; m-- )
> > +                    {
> > +                        e820[m].addr = e820[m-1].addr;
> > +                        e820[m].size = e820[m-1].size;
> > +                        e820[m].type = e820[m-1].type;
> > +                    }
> > +
> > +                    /* Then fill RMRR into that entry. */
> > +                    e820[j+1].addr = rmrr_start;
> > +                    e820[j+1].size = rmrr_end - rmrr_start;
> > +                    e820[j+1].type = E820_RESERVED;
> > +                    nr++;
> > +                }
> > +                insert++;
> > +            }
> > +            /* Already at the end. */
> > +            else if ( (rmrr_start > end) && !start )
> > +            {
> > +                if ( do_insert )
> > +                {
> > +                    e820[nr].addr = rmrr_start;
> > +                    e820[nr].size = rmrr_end - rmrr_start;
> > +                    e820[nr].type = E820_RESERVED;
> > +                    nr++;
> > +                }
> > +                insert++;
> > +            }
> > +        }
> > +    }
> > +
> > +    /* Just return if done. */
> > +    if ( do_insert )
> > +        return nr;
> > +
> > +    /* Fine to construct RMRR mappings into e820. */
> > +    if ( insert == nr_map)
-    if ( insert == nr_map)
+    if ( insert == nr_map )

> > +    {
> > +        do_insert = 1;
> > +        goto do_real_construct;
> > +    }
> > +    /* Overlap. */
> > +    else
> > +    {
> > +        printf("RMRR overlap with those existing e820 entries!\n");
> > +        printf("So we don't construct RMRR mapping in e820!\n");
s/RMRR/DRM

Thanks
Tiejun

> > +    }
> > +
> > +    return nr;
> > +}
> >   /* Create an E820 table based on memory parameters provided in hvm_info. */
> >   int build_e820_table(struct e820entry *e820,
> >                        unsigned int lowmem_reserved_base,
> >                        unsigned int bios_image_base)
> >   {
> >       unsigned int nr = 0;
> > +    struct reserved_device_memory *map = NULL;
> > +    int rc;
> >
> >       if ( !lowmem_reserved_base )
> >               lowmem_reserved_base = 0xA0000;
> > @@ -169,6 +247,29 @@ int build_e820_table(struct e820entry *e820,
> >           nr++;
> >       }
> >
> > +    /* We'd better reserve RMRR mapping for each VM to avoid potential
> > +     * memory conflict.
> > +     */
> > +    if ( hvm_info->nr_reserved_device_memory_map )
> > +    {
> > +        if ( !map )
> > +            map = mem_alloc(hvm_info->nr_reserved_device_memory_map *
> > sizeof(struct reserved_device_memory), 0);
> > +        if ( map )
> > +        {
> > +            rc = get_reserved_device_memory_map(map,
> > +
> > hvm_info->nr_reserved_device_memory_map);
> > +            if ( !rc )
> > +            {
> > +                nr = construct_rmrr_e820_maps(nr,
> > +
> > hvm_info->nr_reserved_device_memory_map,
> > +                                              map,
> > +                                              e820);
> > +            }
> > +        }
> > +        else
> > +            printf("No space to get reserved_device_memory_map!\n");
> > +    }
> > +
> >       return nr;
> >   }
> >
> > --
> > 1.9.1
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