Re: [PATCH v5 1/4] cxl/hdm: Reject switch decoder interleave ways that overflow targets

[Jonathan Cameron <jic23@kernel.org>]

On Fri,  7 Aug 2026 17:05:48 -0700
Alison Schofield <alison.schofield@intel.com> wrote:

> Switch decoder enumeration validates that the interleave ways encoding
> is legal, but not that the resulting number of ways fits the available
> targets. This can overrun the target array (target_list.target_id[])
> during enumeration of 12 or 16 way interleaves.
> 
> Bound the target count where it is established rather than at each use.
> Reject an HDM capability whose reported target count is zero or exceeds
> the target list register capacity, and reject a zero target switch
> decoder allocation in cxl_switch_decoder_init(). Enumeration is then
> left with a single check: reject a decoder whose interleave ways exceed
> the targets it has.
> 
> Add a clarifying comment that target_count is a direct count, not
> 0-based like decoder_count.
> 
> Link: https://sashiko.dev/#/patchset/20260711180755.1779002-1-alison.schofield@intel.com?part=1
> Fixes: d17d0540a0db ("cxl/core/hdm: Add CXL standard decoder enumeration to the core")
> Tested-by: Davidlohr Bueso <dave@stgolabs.net>
> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
> Reviewed-by: Richard Cheng <icheng@nvidia.com>
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>