This ability is now implement upstream like this:

virt-who has parameter --print that will dump host/guests association as a json. Then there is a fake virt backend that will load that json and use it to put the data to SAM/Satellite.

Is this solution acceptable?

Fixed by rebase to virt-who-0.12-1.el6.

CCS has determined that this bug should be described in the RHEL 6.7 Release Notes. Please update the Doc Text field with a summary feature description.

Failed to verify it on virt-who-0.12-2.el6.noarch as virt-who can't send host/gust mapping to SAM server when vcenter forbidden virt-who machine access to it.

Precondition:
Make sure virt-who's system can't access to vcenter directly.

Checked process: 
1. Register system to SAM 
2. Run virt-who at esx mode in command line and also use new option "-p"
[root@hp-z220-06 ~]# virt-who --esx --esx-owner=ACME_Corporation --esx-env=Library --esx-server=10.66.79.68 --esx-username=Administrator --esx-password=qwer1234P! -d -p
[root@hp-z220-06 ~]# virt-who --esx --esx-owner=ACME_Corporation --esx-env=Library --esx-server=10.66.79.68 --esx-username=Administrator --esx-password=qwer1234P! -p -d
2015-04-09 16:27:07,410 INFO: Using configuration "env/cmdline" ("esx" mode)
2015-04-09 16:27:07,520 DEBUG: Log into ESX
2015-04-09 16:28:10,610 ERROR: Virt backend 'env/cmdline' fails with exception:
Traceback (most recent call last):
  File "/usr/share/virt-who/virt/virt.py", line 208, in run
    self._run()
  File "/usr/share/virt-who/virt/esx/esx.py", line 52, in _run
    self.login()
  File "/usr/share/virt-who/virt/esx/esx.py", line 187, in login
    self.sc = self.client.service.RetrieveServiceContent(_this=self.moRef)
  File "/usr/lib/python2.6/site-packages/suds/client.py", line 542, in __call__
    return client.invoke(args, kwargs)
  File "/usr/lib/python2.6/site-packages/suds/client.py", line 602, in invoke
    result = self.send(soapenv)
  File "/usr/lib/python2.6/site-packages/suds/client.py", line 643, in send
    reply = transport.send(request)
  File "/usr/lib/python2.6/site-packages/suds/transport/https.py", line 64, in send
    return  HttpTransport.send(self, request)
  File "/usr/lib/python2.6/site-packages/suds/transport/http.py", line 77, in send
    fp = self.u2open(u2request)
  File "/usr/lib/python2.6/site-packages/suds/transport/http.py", line 118, in u2open
    return url.open(u2request, timeout=tm)
  File "/usr/lib64/python2.6/urllib2.py", line 391, in open
    response = self._open(req, data)
  File "/usr/lib64/python2.6/urllib2.py", line 409, in _open
    '_open', req)
  File "/usr/lib64/python2.6/urllib2.py", line 369, in _call_chain
    result = func(*args)
  File "/usr/lib64/python2.6/urllib2.py", line 1198, in https_open
    return self.do_open(httplib.HTTPSConnection, req)
  File "/usr/lib64/python2.6/urllib2.py", line 1165, in do_open
    raise URLError(err)
URLError: <urlopen error [Errno 110] Connection timed out>
{"hypervisors": []}

Result:
It show some error messages and a null host/guest mapping in the log, it should have three esx hosts in this vcenter. Therefore, reopen it.

The host/guest mapping needs to be obtained with access to the vCenter first. Then write the result (of 'virt-who -p') to some file and create fake hypervisor pointing to this file (according to virt-who-config man page).

Then it no longer needs to be connected to vCenter and should work normally.

Verified it on virt-who-0.12-2.el6.noarch as virt-who can send host/guest mapping to SAM server when it can't access to vcenter directly.

Verified version:
virt-who-0.12-2.el6.noarch
subscription-manager-1.14.1-1.el6.x86_64
python-rhsm-1.14.1-1.el6.x86_64
candlepin-0.9.6.5-1.el6sam.noarch
katello-headpin-1.4.3.28-1.el6sam_splice.noarch

Verified process:
1. Make sure system with virt-who can connect to vcenter, register system and run virt-who with "-p"
[root@hp-z220-06 virt-who.d]# virt-who --esx --esx-owner=ACME_Corporation --esx-env=Library --esx-server=10.66.79.68 --esx-username=Administrator --esx-password=qwer1234P! -p -d > /root/aaa
2. Make sure this system can't connect to vcenter directly.Configure virt-who as the following:
[root@hp-z220-06 virt-who.d]# cat /etc/virt-who.d/virt 
[fake-virt]
type=fake
file=/root/aaa
is_hypervisor=True
owner=ACME_Corporation
env=Library 
[root@hp-z220-06 virt-who.d]# cat /etc/sysconfig/virt-who
VIRTWHO_BACKGROUND=1
VIRTWHO_DEBUG=1
VIRTWHO_INTERVAL=10
3. Restart virt-who service 
[root@hp-z220-06 virt-who.d]# service virt-who restart
4. Check the virt-who log.
2015-04-09 16:59:07,997 [DEBUG]  @virtwho.py:84 - Using config named 'fake-virt'
2015-04-09 16:59:07,997 [INFO]  @virtwho.py:475 - Using configuration "fake-virt" ("fake" mode)
2015-04-09 16:59:07,997 [DEBUG]  @virtwho.py:131 - Starting infinite loop with 10 seconds interval
2015-04-09 16:59:08,150 [INFO]  @subscriptionmanager.py:124 - Sending update in hosts-to-guests mapping: {u'564d20f4-71b7-acdb-f875-d64ecec4a6c0': [u'4226082e-2746-17dc-6f01-dc91c6fc7fbb', u'4224d6d4-b9ef-cd33-8f19-56bcfc179ed5'], u'86b2bd00-8bad-11e2-87f4-6c3be514699d': [u'4224a77f-1c50-42cb-3507-2b68b447ed60', u'4224e5d2-4fcf-2bc2-2559-5846035d3a78']}
2015-04-09 16:59:08,151 [DEBUG]  @subscriptionmanager.py:76 - Authenticating with certificate: /etc/pki/consumer/cert.pem
2015-04-09 16:59:09,065 [INFO]  @virtwho.py:127 - Created host: cd07723f-7032-4a60-9eb4-0c05dc0c2251 with guests: [4226082e-2746-17dc-6f01-dc91c6fc7fbb, 4224d6d4-b9ef-cd33-8f19-56bcfc179ed5]
2015-04-09 16:59:09,065 [INFO]  @virtwho.py:127 - Created host: 1e864c41-0e41-4370-a8f1-8d18fa0ffd49 with guests: [4224a77f-1c50-42cb-3507-2b68b447ed60, 4224e5d2-4fcf-2bc2-2559-5846035d3a78]

Result:virt-who has send the host/guest mapping to SAM, host/guest mapping can show on the SAM web UI. Therefore, verify it.

The format is just quite simple JSON:

{
    "hypervisors": [
        {
            "uuid": "<unique-identification-of-the-host-1>",
            "guests": [
                "<guest-1-uuid>",
                "<guest-2-uuid>",
                "<guest-3-uuid>",
                ...
            ]
        },
        {
            "uuid": "<unique-identification-of-the-host-2>",
            "guests": [
                "<guest-4-uuid>",
                "<guest-5-uuid>",
                "<guest-6-uuid>",
                ...
            ]
        },
        ...
    ]
}

But getting this info from ESX is quite tricky as this information can't be obtained from vSphere Web Client.

It is possible to use MOB:
1) Go to MOB service content: https://<esx-or-vcenter-server>/mob/?moid=ServiceInstance&doPath=content
2) Note value in the 3rd column on line "rootFolder"
3) Then go to https://<esx-or-vcenter-server>/mob/?moid=ha-property-collector&method=retrievePropertiesEx
4) Paste content of following file into the first box and change the comment starting with "<!-- TODO" to value from step 3
5) Increase the 0 in the second box to something high (like 1000)
6) Press "Invoke method"
7) You should see table with hosts and guests and their uuids bellow
8) Use uuid to build JSON as shown above

Sorry, I forgot to paste the link to that file (step 4): https://rnovacek.fedorapeople.org/esx-enumerate.xml

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-1377.html