Fixed upstream with
https://github.com/libguestfs/libguestfs/commit/37955f14aa628bedbe0c06bddb5f8fa4f508cc62
which is in libguestfs >= 1.39.15.

Verify the bug with below builds:
virt-v2v-1.38.4-8.module+el8+2564+79985af8.x86_64
libguestfs-1.38.4-8.module+el8+2564+79985af8.x86_64

Steps:
1.Check "VCENTER: NON-ADMINISTRATOR ROLE" info in v2v man page
 VCENTER: NON-ADMINISTRATOR ROLE
       Instead of using the vCenter Administrator role, you can create a
       custom non-administrator role to perform the conversion.  You will
       however need to give it a minimum set of permissions as follows (using
       VMware vCenter 6.5):

       1.  Create a custom role in vCenter.

       2.  Enable (check) the following objects:

            Datastore:
             - Browse datastore
             - Low level file operations

            Sessions:
             - Validate session

            Virtual Machine:
              Interaction:
                - Guest operating system management by VIX API
              Provisioning:
                - Allow disk access
                - Allow read-only disk access
                - Allow virtual machine download

Hi Pino,

    Categories of "Guest Operating system management by VIX API" is correct now in v2v man page, but I see add new permission "Allow virtual machine download" in Provisioning, is it necessary? Thanks!

(In reply to mxie from comment #3)
>     Categories of "Guest Operating system management by VIX API" is correct
> now in v2v man page, but I see add new permission "Allow virtual machine
> download" in Provisioning, is it necessary?

I tested with VMware vCenter 6.5, and this was needed to properly download the vmx file of the guest (done by the libvirt esx driver).

(In reply to Pino Toscano from comment #4)
> (In reply to mxie from comment #3)
> >     Categories of "Guest Operating system management by VIX API" is correct
> > now in v2v man page, but I see add new permission "Allow virtual machine
> > download" in Provisioning, is it necessary?
> 
> I tested with VMware vCenter 6.5, and this was needed to properly download
> the vmx file of the guest (done by the libvirt esx driver).

Hi Pino,

   As we discussed in RC, I can dump the guest xml from vCenter6.5 by virsh using non-admin account without " Allow virtual machine download" permission", so I think the permission "Allow virtual machine download" is not necessary, could you please help to confirm? Thanks!

# virsh -c  vpx://vsphere.local%5cmxie.lab.eng.brq.redhat.com/DC1/ptoscano-vmware01.tpb.lab.eng.brq.redhat.com/?no_verify=1
Enter vsphere.local\mxie's password for ptoscano-vcsa.tpb.lab.eng.brq.redhat.com: 
Welcome to virsh, the virtualization interactive terminal.

Type:  'help' for help with commands
       'quit' to quit

virsh # dumpxml 'Windows 8'
<domain type='vmware' xmlns:vmware='http://libvirt.org/schemas/domain/vmware/1.0'>
  <name>Windows 8</name>
  <uuid>423855dc-f08e-cdbf-337a-92377f181666</uuid>
  <memory unit='KiB'>4194304</memory>
  <currentMemory unit='KiB'>4194304</currentMemory>
  <vcpu placement='static'>2</vcpu>
  <cputune>
    <shares>2000</shares>
  </cputune>
  <os>
    <type arch='x86_64'>hvm</type>
  </os>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <disk type='file' device='disk'>
      <source file='[ds1] Windows 8/Windows 8.vmdk'/>
      <target dev='sda' bus='scsi'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='scsi' index='0' model='lsisas1068'/>
    <interface type='bridge'>
      <mac address='00:50:56:b8:b7:9f'/>
      <source bridge='VM Network'/>
      <model type='vmxnet3'/>
    </interface>
    <video>
      <model type='vmvga' vram='8192' primary='yes'/>
    </video>
  </devices>
  <vmware:datacenterpath>DC1</vmware:datacenterpath>
  <vmware:moref>vm-57</vmware:moref>
</domain>

OK, it seems to work fine also without the "Allow virtual machine download" permission:
https://github.com/libguestfs/libguestfs/commit/5e5896752ef06872696f1da05b414fc9eca94015

Verify the bug with below builds:
virt-v2v-1.38.4-9.module+el8+2655+d5607577.x86_64
libguestfs-1.38.4-9.module+el8+2655+d5607577.x86_64

Steps:
1.Check "VCENTER: NON-ADMINISTRATOR ROLE" info in v2v man page
#man virt-v2v
....
 VCENTER: NON-ADMINISTRATOR ROLE
       Instead of using the vCenter Administrator role, you can create a
       custom non-administrator role to perform the conversion.  You will
       however need to give it a minimum set of permissions as follows (using
       VMware vCenter 6.5):

       1.  Create a custom role in vCenter.

       2.  Enable (check) the following objects:

            Datastore:
             - Browse datastore
             - Low level file operations

            Sessions:
             - Validate session

            Virtual Machine:
              Interaction:
                - Guest operating system management by VIX API
              Provisioning:
                - Allow disk access
                - Allow read-only disk access
           
Result:
    The Categories of "Guest Operating system management by VIX API" is correct in v2v man page now, so move the bug from ON_QA to VERIFIED