cxl/port: Fix decoder initialization when nr_targets > interleave_ways

stable inclusion
from stable-v6.6.14
commit 5a473e32088c3c6d02e4185d8d4cb9f58ce4b528
bugzilla: https://gitee.com/openeuler/kernel/issues/I99TJK

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5a473e32088c3c6d02e4185d8d4cb9f58ce4b528



--------------------------------

commit d6488fee66472b468ed88d265b14aa3f04dc3bdf upstream.

The decoder_populate_targets() helper walks all of the targets in a port
and makes sure they can be looked up in @target_map. Where @target_map
is a lookup table from target position to target id (corresponding to a
cxl_dport instance). However @target_map is only responsible for
conveying the active dport instances as indicated by interleave_ways.

When nr_targets > interleave_ways it results in
decoder_populate_targets() walking off the end of the valid entries in
@target_map. Given target_map is initialized to 0 it results in the
dport lookup failing if position 0 is not mapped to a dport with an id
of 0:

  cxl_port port3: Failed to populate active decoder targets
  cxl_port port3: Failed to add decoder
  cxl_port port3: Failed to add decoder3.0
  cxl_bus_probe: cxl_port port3: probe: -6

This bug also highlights that when the decoder's ->targets[] array is
written in cxl_port_setup_targets() it is missing a hold of the
targets_lock to synchronize against sysfs readers of the target list. A
fix for that is saved for a later patch.

Fixes: a5c25802 ("cxl/bus: Populate the target list at decoder create")
Cc:  <stable@vger.kernel.org>
Signed-off-by: Huang, Ying <ying.huang@intel.com>
[djbw: rewrite the changelog, find the Fixes: tag]
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>