[libvirt] [Qemu-devel] [PATCH V17 02/11] NUMA: check if the total numa memory size is equal to ram_size

[Eduardo Habkost]

CCing libvir-list.

On Wed, Dec 04, 2013 at 03:58:50PM +0800, Wanlong Gao wrote:
> If the total number of the assigned numa nodes memory is not
> equal to the assigned ram size, it will write the wrong data
> to ACPI talb, then the guest will ignore the wrong ACPI table
> and recognize all memory to one node. It's buggy, we should
> check it to ensure that we write the right data to ACPI table.
> 
> Signed-off-by: Wanlong Gao <gaowanlong at cn.fujitsu.com>

This will make configurations that could be running for years (except
that the guest OS was ignoring the NUMA data) suddenly stop running. I
just want to confirm: we really want that, right?

Does libvirt allow this kind of broken configuration to be generated, or
it already ensures the total NUMA node sizes match RAM size?


> ---
>  numa.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/numa.c b/numa.c
> index ce7736a..beda80e 100644
> --- a/numa.c
> +++ b/numa.c
> @@ -150,6 +150,16 @@ void set_numa_nodes(void)
>              node_mem[i] = ram_size - usedmem;
>          }
>  
> +        uint64_t numa_total = 0;
> +        for (i = 0; i < nb_numa_nodes; i++) {
> +            numa_total += node_mem[i];
> +        }
> +        if (numa_total != ram_size) {
> +            fprintf(stderr, "qemu: numa nodes total memory size "
> +                            "should equal to ram_size\n");
> +            exit(1);
> +        }
> +
>          for (i = 0; i < nb_numa_nodes; i++) {
>              if (!bitmap_empty(node_cpumask[i], MAX_CPUMASK_BITS)) {
>                  break;
> -- 
> 1.8.5
> 
> 

-- 
Eduardo