[Xen-devel] [RFC][PATCH 4/5] tools:firmware:hvmloader: reserve RMRR mappings in e820

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.08.14 at 13:02, <tiejun.chen@xxxxxxxxx> wrote:
> We need to reserve all RMRR mappings in e820 to avoid any
> potential guest memory conflict.
> 
> Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
> ---
>  tools/firmware/hvmloader/e820.c | 14 ++++++++++++++
>  tools/firmware/hvmloader/e820.h |  6 ++++++
>  tools/firmware/hvmloader/util.c | 13 +++++++++++++
>  tools/firmware/hvmloader/util.h |  1 +
>  4 files changed, 34 insertions(+)

> @@ -124,6 +126,18 @@ int build_e820_table(struct e820entry *e820,
>      e820[nr].type = E820_RAM;
>      nr++;
>  
> +    /* We'd better reserve RMRR mapping for each VM to avoid potential
> +     * memory conflict.
> +     */
> +    e820_rmrr_map = get_rmrr_map_info();
> +    for ( i = 0; i <= e820_rmrr_map->nr_map; i++ )
> +    {
> +        e820[nr].addr = e820_rmrr_map->map[i].addr;
> +        e820[nr].size = e820_rmrr_map->map[i].size + 1;
> +        e820[nr].type = E820_RESERVED;
> +        nr++;
> +    }

You can't just put this in an arbitrary place, without caring for overlaps
(and ordering perhaps - I don't recall offhand whether E820 is
required to be sorted, or whether that's just common practice). In fact
I'm not certain the code block following your insertion (interestingly
another Intel special) doesn't violate this too.

Jan


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