virhostcpu.c: fix 'die_id' parsing for Power hosts
virhostcpu.c: fix 'die_id' parsing for Power hosts

Commit 7b79ee2f78 makes assumptions about die_id parsing in
the sysfs that aren't true for Power hosts. In both Power8
and Power9, running 5.6 and 4.18 kernel respectively,
'die_id' is set to -1:

$ cat /sys/devices/system/cpu/cpu0/topology/die_id
-1

This breaks virHostCPUGetDie() parsing because it is trying to
retrieve an unsigned integer, causing problems during VM start:

virFileReadValueUint:4128 : internal error: Invalid unsigned integer
value '-1' in file '/sys/devices/system/cpu/cpu0/topology/die_id'

This isn't necessarily a PowerPC only behavior. Linux kernel commit
0e344d8c70 added in the former Documentation/cputopology.txt, now
Documentation/admin-guide/cputopology.rst, that:

  To be consistent on all architectures, include/linux/topology.h
  provides default definitions for any of the above macros that are
  not defined by include/asm-XXX/topology.h:

  1) topology_physical_package_id: -1
  2) topology_die_id: -1
  (...)

This means that it might be expected that an architecture that
does not implement the die_id element will mark it as -1 in
sysfs.

It is not required to change die_id implementation from uInt to
Int because of that. Instead, let's change the parsing of the
die_id in virHostCPUGetDie() to read an integer value and, in
case it's -1, default it to zero like in case of file not found.
This is enough to solve the issue Power hosts are experiencing.

Fixes: 7b79ee2f78bbf2af76df2f6466919e19ae05aeeb
Signed-off-by: Daniel Henrique Barboza <627b089ad62deae9aaf06ccfa2c9056df28927e0@gmail.com>
Reviewed-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

fabianfreyer/libvirt,jfehlig/libvirt,zippy2/libvirt,libvirt/libvirt,crobinso/libvirt,jardasgit/libvirt,olafhering/libvirt,olafhering/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,jardasgit/libvirt,olafhering/libvirt,nertpinx/libvirt,olafhering/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,jardasgit/libvirt,crobinso/libvirt,libvirt/libvirt,zippy2/libvirt,nertpinx/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,crobinso/libvirt,jfehlig/libvirt,zippy2/libvirt,fabianfreyer/libvirt,zippy2/libvirt,crobinso/libvirt,nertpinx/libvirt,libvirt/libvirt,nertpinx/libvirt,libvirt/libvirt,nertpinx/libvirt