Re: [PATCH for 4.6 v2 3/3] xl/libxl: disallow saving a guest with vNUMA configured

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 09/09/2015 01:03 PM, Wei Liu wrote:
> This is due to migration v2 frame record doesn't contain node
> information.
>
> Signed-off-by: Wei Liu <wei.liu2@citrix.com>
> ---
> Cc: andrew.cooper3@citrix.com
> ---
>   docs/man/xl.cfg.pod.5   |  2 ++
>   tools/libxl/libxl_dom.c | 14 ++++++++++++++
>   2 files changed, 16 insertions(+)
>
> diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
> index 80e51bb..dbd0700 100644
> --- a/docs/man/xl.cfg.pod.5
> +++ b/docs/man/xl.cfg.pod.5
> @@ -263,6 +263,8 @@ virtual node.
>   
>   Note that virtual NUMA for PV guest is not yet supported, because
>   there is an issue with cpuid handling that affects PV virtual NUMA.
> +Further more, guest with virtual NUMA cannot be saved or migrated
> +because node information of guest frames is not preserved.

Should we also issue a warning during startup if nomigrate is not set?

-boris

>   
>   Each B<VNODE_SPEC> is a list, which has a form of
>   "[VNODE_CONFIG_OPTION,VNODE_CONFIG_OPTION, ... ]"  (without quotes).
> diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
> index c2518a3..5dc4d3a 100644
> --- a/tools/libxl/libxl_dom.c
> +++ b/tools/libxl/libxl_dom.c
> @@ -24,6 +24,7 @@
>   #include <xen/hvm/hvm_info_table.h>
>   #include <xen/hvm/hvm_xs_strings.h>
>   #include <xen/hvm/e820.h>
> +#include <xen/errno.h>
>   
>   libxl_domain_type libxl__domain_type(libxl__gc *gc, uint32_t domid)
>   {
> @@ -1612,6 +1613,7 @@ void libxl__domain_save(libxl__egc *egc, libxl__domain_suspend_state *dss)
>       const libxl_domain_remus_info *const r_info = dss->remus;
>       libxl__srm_save_autogen_callbacks *const callbacks =
>           &dss->sws.shs.callbacks.save.a;
> +    unsigned int nr_vnodes = 0, nr_vmemranges = 0, nr_vcpus = 0;
>   
>       dss->rc = 0;
>       logdirty_init(&dss->logdirty);
> @@ -1636,6 +1638,18 @@ void libxl__domain_save(libxl__egc *egc, libxl__domain_suspend_state *dss)
>             | (debug ? XCFLAGS_DEBUG : 0)
>             | (dss->hvm ? XCFLAGS_HVM : 0);
>   
> +    /* Disallow saving a guest with vNUMA configured because migration
> +     * v2 record doesn't contain node information for guest frame.
> +     */
> +    rc = xc_domain_getvnuma(CTX->xch, domid, &nr_vnodes, &nr_vmemranges,
> +                            &nr_vcpus, NULL, NULL, NULL);
> +    assert(rc == -1 && (errno == XEN_ENOBUFS || errno == XEN_EOPNOTSUPP));
> +    if (errno == XEN_ENOBUFS && nr_vnodes) {
> +        LOG(ERROR, "Cannot save a guest with vNUMA configured");
> +        rc = ERROR_FAIL;
> +        goto out;
> +    }
> +
>       dss->guest_evtchn.port = -1;
>       dss->guest_evtchn_lockfd = -1;
>       dss->guest_responded = 0;