xen-devel.lists.xenproject.org archive mirror
 help / color / mirror / Atom feed
From: Wei Liu <wei.liu2@citrix.com>
To: Anthony PERARD <anthony.perard@citrix.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
	Wei Liu <wei.liu2@citrix.com>,
	Ian Jackson <Ian.Jackson@eu.citrix.com>
Subject: Re: [PATCH v2 2/3] libxl: update vcpus bitmap in retrieved guest config
Date: Mon, 13 Jun 2016 19:21:53 +0100	[thread overview]
Message-ID: <20160613182153.GC23146@citrix.com> (raw)
In-Reply-To: <20160613173936.GG5666@perard.uk.xensource.com>

On Mon, Jun 13, 2016 at 06:39:36PM +0100, Anthony PERARD wrote:
> On Wed, Jun 08, 2016 at 03:28:45PM +0100, Wei Liu wrote:
> > ... because the available vcpu bitmap can change during domain life time
> > due to cpu hotplug and unplug.
> > 
> > For QEMU upstream, we interrogate QEMU for the number of vcpus. For
> > others, we look directly into xenstore for information.
> 
> I tried to migrate a guest, and libxl abort in
> libxl_retrieve_domain_configuration within the switch
> (device_model_version).
> 
> 
> > Reported-by: Jan Beulich <jbeulich@suse.com>
> > Signed-off-by: Wei Liu <wei.liu2@citrix.com>
> > ---
> >  tools/libxl/libxl.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 87 insertions(+)
> > 
> > diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> > index 006b83f..02706ab 100644
> > --- a/tools/libxl/libxl.c
> > +++ b/tools/libxl/libxl.c
> > @@ -7222,6 +7222,53 @@ void libxl_mac_copy(libxl_ctx *ctx, libxl_mac *dst, libxl_mac *src)
> >          (*dst)[i] = (*src)[i];
> >  }
> >  
> > +static int libxl__update_avail_vcpus_qmp(libxl__gc *gc, uint32_t domid,
> > +                                         unsigned int max_vcpus,
> > +                                         libxl_bitmap *map)
> > +{
> > +    int rc;
> > +
> > +    /* For QEMU upstream we always need to return the number
> > +     * of cpus present to QEMU whether they are online or not;
> > +     * otherwise QEMU won't accept the saved state.
> > +     */
> > +    rc = libxl__qmp_query_cpus(gc, domid, map);
> > +    if (rc) {
> > +        LOG(ERROR, "fail to get number of cpus for domain %d", domid);
> > +        goto out;
> > +    }
> > +
> > +    rc = 0;
> 
> The value should already be 0 at this point.
> 

I would like to keep this as-is because this is an idiom that is safer
against further modification of this function.

> > +out:
> > +    return rc;
> > +}
> > +
> > +static int libxl__update_avail_vcpus_xenstore(libxl__gc *gc, uint32_t domid,
> > +                                              unsigned int max_vcpus,
> > +                                              libxl_bitmap *map)
> > +{
> > +    int rc;
> > +    unsigned int i;
> > +    const char *dompath;
> > +
> > +    dompath = libxl__xs_get_dompath(gc, domid);
> > +    if (!dompath) {
> > +        rc = ERROR_FAIL;
> > +        goto out;
> > +    }
> > +
> > +    for (i = 0; i < max_vcpus; i++) {
> > +        const char *path = GCSPRINTF("%s/cpu/%u/availability", dompath, i);
> > +        const char *content = libxl__xs_read(gc, XBT_NULL, path);
> > +        if (!strncmp(content, "online", strlen("online")))
> 
> I don't think strncmp is usefull here as one of the argument is a plain
> string. One could just use strcmp?
> 

Fine by me of course.

> > +            libxl_bitmap_set(map, i);
> > +    }
> > +
> > +    rc = 0;
> > +out:
> > +    return rc;
> > +}
> > +
> >  int libxl_retrieve_domain_configuration(libxl_ctx *ctx, uint32_t domid,
> >                                          libxl_domain_config *d_config)
> >  {
> > @@ -7270,6 +7317,46 @@ int libxl_retrieve_domain_configuration(libxl_ctx *ctx, uint32_t domid,
> >          libxl_dominfo_dispose(&info);
> >      }
> >  
> > +    /* VCPUs */
> > +    {
> > +        libxl_bitmap *map = &d_config->b_info.avail_vcpus;
> > +        unsigned int max_vcpus = d_config->b_info.max_vcpus;
> > +
> > +        libxl_bitmap_dispose(map);
> > +        libxl_bitmap_init(map);
> > +        libxl_bitmap_alloc(CTX, map, max_vcpus);
> > +        libxl_bitmap_set_none(map);
> > +
> > +        switch (d_config->b_info.type) {
> > +        case LIBXL_DOMAIN_TYPE_HVM:
> > +            switch (d_config->b_info.device_model_version) {
> > +            case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN:
> > +                rc = libxl__update_avail_vcpus_qmp(gc, domid,
> > +                                                   max_vcpus, map);
> > +                break;
> > +            case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL:
> > +            case LIBXL_DEVICE_MODEL_VERSION_NONE:
> > +                rc = libxl__update_avail_vcpus_xenstore(gc, domid,
> > +                                                        max_vcpus, map);
> > +                break;
> > +            default:
> > +            abort();
> 
> Missing indentation for abort.
> 

Will fix.

> Also, that is where xl abort on migration.
> 

Hmm...  This means the device model version is not valid (unknown?).

Can you paste in your guest config?

Wei.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel

  reply	other threads:[~2016-06-13 18:21 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-08 14:28 [PATCH v2 0/3] libxl: libxl: update available vcpus map in retrieve configuration function Wei Liu
2016-06-08 14:28 ` [PATCH v2 1/3] libxl: introduce libxl__qmp_query_cpus Wei Liu
2016-06-09  0:12   ` Dario Faggioli
2016-06-13 16:52   ` Anthony PERARD
2016-06-13 18:17     ` Wei Liu
2016-06-08 14:28 ` [PATCH v2 2/3] libxl: update vcpus bitmap in retrieved guest config Wei Liu
2016-06-09  0:11   ` Dario Faggioli
2016-06-13 17:39   ` Anthony PERARD
2016-06-13 18:21     ` Wei Liu [this message]
2016-06-14 10:47       ` Anthony PERARD
2016-06-14 10:50         ` Wei Liu
2016-06-14 10:58           ` Anthony PERARD
2016-06-14 11:00             ` Wei Liu
2016-06-14 16:27               ` Ian Jackson
2016-06-14 13:20             ` Anthony PERARD
2016-06-08 14:28 ` [PATCH v2 3/3] libxl: only issue cpu-add call to QEMU for not present CPU Wei Liu
2016-06-08 15:01   ` Jan Beulich
2016-06-13 17:47   ` Anthony PERARD

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20160613182153.GC23146@citrix.com \
    --to=wei.liu2@citrix.com \
    --cc=Ian.Jackson@eu.citrix.com \
    --cc=anthony.perard@citrix.com \
    --cc=xen-devel@lists.xenproject.org \
    --subject='Re: [PATCH v2 2/3] libxl: update vcpus bitmap in retrieved guest config' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).