On 1/7/26 10:25 PM, Alison Schofield wrote:
> Add a test case to validate that all switch port decoders sharing
> downstream ports, dports, have target lists properly enumerated.
>
> This test catches the regression fixed by a recent kernel patch[1]
> where only one decoder per switch port has targets populated while
> others have nr_targets=0, even when dports are available.
>
> This test is based on the current cxl_test topology which provides
> multiple switch ports with 8 decoders each. Like other testcases in
> cxl-topology.sh, if the cxl_test topology changes (number of switches,
> decoders per port, or hierarchy), this test will need corresponding
> updates.
>
> This new case is quietly skipped with kernel version 6.18 where it
> is known broken.
>
> [1]
> https://lore.kernel.org/linux-cxl/[email protected]/
>
> Signed-off-by: Alison Schofield <[email protected]>
> ---
>
> test/common | 12 +++++++++++
> test/cxl-topology.sh | 51 ++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 63 insertions(+)
>
> diff --git a/test/common b/test/common
> index 2d076402ef7c..2eb11b7396d0 100644
> --- a/test/common
> +++ b/test/common
> @@ -101,6 +101,18 @@ check_min_kver()
> [[ "$ver" == "$(echo -e "$ver\n$KVER" | sort -V | head -1)" ]]
> }
>
> +# check_eq_kver
> +# $1: Kernel version to match. format: X.Y
> +#
> +check_eq_kver()
> +{
> + local ver="$1"
> + : "${KVER:=$(uname -r)}"
> +
> + [ -n "$ver" ] || return 1
> + [[ "$KVER" == "$ver"* ]]
> +}
> +
> # do_skip
> # $1: Skip message
> #
> diff --git a/test/cxl-topology.sh b/test/cxl-topology.sh
> index b68cb8b262b6..d9475b1bae9c 100644
> --- a/test/cxl-topology.sh
> +++ b/test/cxl-topology.sh
> @@ -151,6 +151,57 @@ count=$(jq "map(select(.pmem_size == $pmem_size)) |
> length" <<< $json)
> ((bridges == 2 && count == 8 || bridges == 3 && count == 10 ||
> bridges == 4 && count == 11)) || err "$LINENO"
>
> +# Test that switch port decoders have complete target list enumeration
> +# Validates a fix for multiple decoders sharing the same dport.
> +# Based on the cxl_test topology expectation of switch ports at depth 2
> +# with 8 decoders each. Adjust if that expectation changes.
> +test_switch_decoder_target_enumeration() {
> +
> + # Get verbose output to see targets arrays
> + json=$($CXL list -b cxl_test -vvv)
> +
> + switch_port_issues=$(jq '
> + # Find all switch ports (depth 2)
> + [.. | objects | select(.depth == 2 and has("decoders:" + .port))] |
> +
> + # For each switch port, analyze its decoder target pattern
> + map({
> + port: .port,
> + nr_dports: .nr_dports,
> +
> + # Count non-endpoint decoders (no "mode" field)
> + total: ([to_entries[] | select(.key | startswith("decoders:"))
> + | .value[] | select(has("mode") == false)] |
> + length),
> +
> + # Count how many have targets
> + with_targets: ([to_entries[] | select(.key |
> + startswith("decoders:")) | .value[] |
> + select(has("mode") == false and .nr_targets > 0)] |
> + length),
> +
> + # Count how many explicitly have no targets
> + without_targets: ([to_entries[] | select(.key |
> + startswith("decoders:")) | .value[] |
> + select(has("mode") == false and .nr_targets == 0)] |
> + length)
> + }) |
> +
> + # Filter for the expected pattern and count them
> + map(select(.nr_dports > 0 and
> + .with_targets == 1 and
> + .without_targets >= 7)) |
> + length
> + ' <<<"$json")
> +
> + ((switch_port_issues == 0)) || {
> + echo "Found $switch_port_issues switch ports with incomplete
> target enumeration"
> + echo "Only 1 decoder has targets while 7+ have nr_targets=0"
> + err "$LINENO"
> + }
> +}
> +# Skip the target enumeration test where known broken
> +check_eq_kver 6.18 || test_switch_decoder_target_enumeration
6.19 I believe?
DJ
>
> # check that switch ports disappear after all of their memdevs have been
> # disabled, and return when the memdevs are enabled.
