Re: [PATCH 2/4] libxc: report how much memory a domain has on each NUMA node

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 05/03/14 14:36, Dario Faggioli wrote:
> by means of a new interface: xc_domain_numainfo().
>
> The caller is expected to allocate an array for the call to fill,
> with the results of the XEN_DOMCTL_numainfo hypercall. The size of
> the array is also passed to the function, which then returns back
> the number of elements that have actually been filled by Xen.
>
> Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
> ---
>  tools/libxc/xc_domain.c |   28 ++++++++++++++++++++++++++++
>  tools/libxc/xenctrl.h   |   18 ++++++++++++++++++
>  2 files changed, 46 insertions(+)
>
> diff --git a/tools/libxc/xc_domain.c b/tools/libxc/xc_domain.c
> index 369c3f3..a2b3c07 100644
> --- a/tools/libxc/xc_domain.c
> +++ b/tools/libxc/xc_domain.c
> @@ -362,6 +362,34 @@ int xc_domain_getinfo(xc_interface *xch,
>      return nr_doms;
>  }
>  
> +int xc_domain_numainfo(xc_interface *xch, uint32_t domid,
> +                       int *max_nodes, uint64_t *memkbs)

max_nodes is an unsigned quantity.  libxc is quite fast and loose with
this, but lets not propage wrongness.

> +{
> +    DECLARE_DOMCTL;
> +    DECLARE_HYPERCALL_BOUNCE(memkbs, sizeof(uint64_t) * (*max_nodes),
> +                             XC_HYPERCALL_BUFFER_BOUNCE_OUT);
> +    int ret = 0;

Don't need the initialiser.

> +
> +    if ( xc_hypercall_bounce_pre(xch, memkbs) )
> +    {
> +        PERROR("Could not allocate bounce buffer for DOMCTL_domain_numainfo");
> +        return -1;
> +    }
> +
> +    domctl.cmd = XEN_DOMCTL_numainfo;
> +    domctl.domain = (domid_t)domid;
> +    domctl.u.numainfo.max_node_index = *max_nodes - 1;
> +    set_xen_guest_handle(domctl.u.numainfo.memkb_on_node, memkbs);
> +
> +    ret = do_domctl(xch, &domctl);
> +
> +    *max_nodes = domctl.u.numainfo.max_node_index + 1;

If the domctl fails, this should not be written back to *max_nodes.

~Andrew

> +
> +    xc_hypercall_bounce_post(xch, memkbs);
> +
> +    return ret;
> +}
> +
>  int xc_domain_getinfolist(xc_interface *xch,
>                            uint32_t first_domain,
>                            unsigned int max_domains,
> diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
> index 13f816b..845d183 100644
> --- a/tools/libxc/xenctrl.h
> +++ b/tools/libxc/xenctrl.h
> @@ -657,6 +657,24 @@ int xc_domain_getinfolist(xc_interface *xch,
>                            xc_domaininfo_t *info);
>  
>  /**
> + * This function tells how much memory a domain has allocated on each
> + * online NUMA node of the host. The information is stored in an array
> + * that the caller provides, along with its size. The function updates
> + * the latter parameter with the number of elements in the array that
> + * have been actually filled.
> + *
> + * @param xch a handle to an open hypervisor interface
> + * @param domid the domain id for which we want the information
> + * @param max_nodes as an input, the size of the memkbs array; as an
> + *                  output, the number of filled elements in it
> + * @param memkbs an array with, in the i-eth element, the memory, in
> + *               Kb, allocated for the domain on the i-eth NUMA node
> + * @return 0 on success, -1 on failure
> + */
> +int xc_domain_numainfo(xc_interface *xch, uint32_t domid,
> +                       int *max_nodes, uint64_t *memkbs);
> +
> +/**
>   * This function set p2m for broken page
>   * &parm xch a handle to an open hypervisor interface
>   * @parm domid the domain id which broken page belong to
>