From: Anthony PERARD <anthony.perard@citrix.com>
To: Wei Liu <wei.liu2@citrix.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
Ian Jackson <Ian.Jackson@eu.citrix.com>
Subject: Re: [PATCH v2 2/3] libxl: update vcpus bitmap in retrieved guest config
Date: Tue, 14 Jun 2016 11:47:57 +0100 [thread overview]
Message-ID: <20160614104757.GI5666@perard.uk.xensource.com> (raw)
In-Reply-To: <20160613182153.GC23146@citrix.com>
On Mon, Jun 13, 2016 at 07:21:53PM +0100, Wei Liu wrote:
> 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?
With all commented line removed:
builder = 'hvm'
memory = 500
vcpus = 2
maxvcpus = 6
name = "arch"
vif = [ 'type=ioemu,mac=00:16:3e:XX:XX:XX' ]
disk = [
'phy:/dev/vg42/guest_arch64,hda,w',
'file:/root/vm/iso/archlinux-2014.04.01-dual.iso,hdc:cdrom,r',
]
device_model_args_hvm = [
]
usbdevice='tablet'
boot="cd"
serial='pty'
sdl = 0
vnc = 1
vnclisten = '0.0.0.0'
vncunused = 1
spice=0
uuid = "XXXX"
--
Anthony PERARD
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Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
next prev parent reply other threads:[~2016-06-14 10:48 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
2016-06-14 10:47 ` Anthony PERARD [this message]
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
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