Re: [PATCH v3 3/7] libxl: In libxl_set_vcpuonline check for maximum number of VCPUs against the cpumap.

[Ian Campbell <ian.campbell@citrix.com>]

On Mon, 2015-03-23 at 14:20 -0400, Konrad Rzeszutek Wilk wrote:
> There is no sense in trying to online (or offline) CPUs when the size of
> cpumap is greater than the maximum number of VCPUs the guest can go to.
> 
> As such fail the operation if the count of CPUs to online is greater
> than what the guest started with. For the offline case we do not
> check (as the bits are unset in the cpumap) and let it go through.
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>  tools/libxl/libxl.c | 27 ++++++++++++++++++++++++---
>  1 file changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index 4152ee4..d2b5ff3 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -5449,6 +5449,20 @@ int libxl_domain_get_nodeaffinity(libxl_ctx *ctx, uint32_t domid,
>      return 0;
>  }
>  
> +static int libxl__check_max(libxl__gc *gc, libxl_dominfo *info,
> +                            libxl_bitmap *cpumap)
> +{
> +    int maxcpus = libxl_bitmap_count_set(cpumap);
> +
> +    if (maxcpus > info->vcpu_max_id + 1)
> +    {
> +        LOGE(ERROR, "You have a max of %d vCPUs and you want %d vCPUs!",
> +             info->vcpu_max_id + 1, maxcpus);

Please avoid personal pronouns in libxl logs (I don't have a max of any
number of vcpus, the domain does). Here "setting %d vcpus, max vcpus is
%d" perhaps.

Both libxl__set_vcpuonline_qmp and libxl__set_vcpuonline_xenstore start
with the same code to get info. Please could you move that (and the
associated dispose) into libxl_set_vcpuonline and check the limit once
up front (no need for helper then) and pass the info as a pointer to the
specific functions.

Ian.