cxl/fwctl: Propagate feature RPC delivery errors

FWCTL_RPC requires delivery failures to be returned as ioctl errors,
while device errors are reported in the output. Get and Set Feature
instead converted all failures into normal responses, sometimes with a
SUCCESS device status.

Initialize the return code to SUCCESS. When the helper fails without a
device error code, return its errno. Continue reporting actual device
errors through rpc_out->retval.

CXL permits Get Feature to return a nonzero short payload when Offset +
Count runs past the end of the Feature. cxl_internal_send_cmd() reports
that response as -EIO, so preserve the returned bytes as a successful
partial transfer. Fixed-format EDAC callers still require complete
attribute structures, so reject partial payloads before consuming them.

Map an unexpected zero-length result with a SUCCESS device status to
-EIO.

Fixes: 5908f3ed6dc2 ("cxl: Add support to handle user feature commands for get feature")
Fixes: eb5dfcb9e36d ("cxl: Add support to handle user feature commands for set feature")
Signed-off-by: Richard Cheng <icheng@nvidia.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://patch.msgid.link/20260902053839.25595-8-icheng@nvidia.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

0 files changed, 0 insertions, 0 deletions