Description:
For virsh allocpages command, using some negative values test, report error should be improved

Version-Release number of selected component (if applicable):
libvirt-1.2.15-2.el7.x86_64
qemu-kvm-rhev-2.3.0-1.el7.x86_64
3.10.0-243.el7.x86_64


How reproducible:
100%

Steps:

1. check NUMA host virsh capabilities,two cells exist
# virsh capabilities |grep cell 
...
<cells num='2'>
        <cell id='0'>
          <memory unit='KiB'>67086628</memory>
          <pages unit='KiB' size='4'>16246345</pages>
          <pages unit='KiB' size='2048'>2</pages>
          <pages unit='KiB' size='1048576'>2</pages>
          <distances>
            <sibling id='0' value='10'/>
            <sibling id='1' value='11'/>
          </distances>
          <cpus num='8'>
            <cpu id='0' socket_id='0' core_id='1' siblings='0'/>
            <cpu id='1' socket_id='0' core_id='2' siblings='1'/>
            <cpu id='2' socket_id='0' core_id='8' siblings='2'/>
            <cpu id='3' socket_id='0' core_id='9' siblings='3'/>
            <cpu id='4' socket_id='0' core_id='16' siblings='4'/>
            <cpu id='5' socket_id='0' core_id='17' siblings='5'/>
            <cpu id='6' socket_id='0' core_id='18' siblings='6'/>
            <cpu id='7' socket_id='0' core_id='24' siblings='7'/>
          </cpus>
        </cell>
        <cell id='1'>
          <memory unit='KiB'>67108864</memory>
          <pages unit='KiB' size='4'>15996928</pages>
          <pages unit='KiB' size='2048'>500</pages>
          <pages unit='KiB' size='1048576'>2</pages>
          <distances>
            <sibling id='0' value='11'/>
            <sibling id='1' value='10'/>
          </distances>
          <cpus num='8'>
            <cpu id='8' socket_id='3' core_id='0' siblings='8'/>
            <cpu id='9' socket_id='3' core_id='1' siblings='9'/>
            <cpu id='10' socket_id='3' core_id='2' siblings='10'/>
            <cpu id='11' socket_id='3' core_id='8' siblings='11'/>
            <cpu id='12' socket_id='3' core_id='17' siblings='12'/>
            <cpu id='13' socket_id='3' core_id='18' siblings='13'/>
            <cpu id='14' socket_id='3' core_id='24' siblings='14'/>
            <cpu id='15' socket_id='3' core_id='25' siblings='15'/>
          </cpus>
        </cell>
      </cells>
...

2. allocate some pages for cell with positive values, command success
# virsh allocpages --pagesize 2048 --pagecount 5 --cellno 1

# virsh allocpages --pagesize 2048 --pagecount 4 --all

3. set cellno with negative value, for -1, no error report

# virsh allocpages --pagesize 2048 --pagecount 5 --cellno -1

# echo $?
0

3. set cellno with negative value, for -2 or others, error report, but it should be improved to show more clearly and reasonable

# virsh allocpages --pagesize 2048 --pagecount 5 --cellno -2
error: Failed to open file '/sys/devices/system/node/node-2/hugepages/hugepages-2048kB/nr_hugepages': No such file or directory

[root@ibm-x3850x5-04 ~]# echo $?
1

4. the same error as below should be improved also
# virsh allocpages --pagesize 2049 --pagecount 4   <---- pagesize 2049 not supported, but report error should be improved
error: Failed to open file '/sys/kernel/mm/hugepages/hugepages-2049kB/nr_hugepages': No such file or directory

# virsh allocpages --pagesize -1 --pagecount 4    
error: pagesize has to be a number
error: numerical overflow: value too large: 18446744073709551615


# virsh allocpages --pagesize 2048 --pagecount -1 --cellno 0
error: pagecount has to be a number


Actual result:
Report errors are not suitable

Expect result:
Report error for virsh allocpages should be improved more clearly