Re: [PATCH 2/2] hw/cxl: Exclude Discovery from Media Operation Discovery output

[Jonathan Cameron <jonathan.cameron@huawei.com>]

On Wed, 18 Mar 2026 11:55:08 -0700
Davidlohr Bueso <dave@stgolabs.net> wrote:

> Per CXL 4.0 Table 8-331, the Discovery operation "returns a list of
> all Media Operations that the device supports, with the exception of
> the Discovery operation (Class=0, Subclass=0)."
> 
> Filter out Discovery entries when building the output list and adjust
> total_supported_operations accordingly.
> 
> Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Both could do with a fixes tag.

> ---
>  hw/cxl/cxl-mailbox-utils.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
> index 71a012121c87..6932db963788 100644
> --- a/hw/cxl/cxl-mailbox-utils.c
> +++ b/hw/cxl/cxl-mailbox-utils.c
> @@ -2593,7 +2593,7 @@ static CXLRetCode media_operations_discovery(uint8_t *payload_in,
>      } QEMU_PACKED *media_op_in_disc_pl = (void *)payload_in;
>      struct media_op_discovery_out_pl *media_out_pl =
>          (struct media_op_discovery_out_pl *)payload_out;
> -    int total = ARRAY_SIZE(media_op_matrix);
> +    int total = ARRAY_SIZE(media_op_matrix) - 1; /* exclude Discovery */
>      int num_ops, start_index, i;
>      int count = 0;
>  
> @@ -2619,10 +2619,12 @@ static CXLRetCode media_operations_discovery(uint8_t *payload_in,
>  
>      num_ops = MIN(num_ops, total - start_index);
>      for (i = 0; i < num_ops; i++) {
> +        int idx = start_index + i + 1; /* skip Discovery (first entry) */
> +
>          media_out_pl->entry[count].media_op_class =
> -                media_op_matrix[start_index + i].media_op_class;
> +                media_op_matrix[idx].media_op_class;
>          media_out_pl->entry[count].media_op_subclass =
> -                    media_op_matrix[start_index + i].media_op_subclass;
> +                    media_op_matrix[idx].media_op_subclass;
Indent comment follows through.

Otherwise LGTM.

I'll queue it up locally but if you want to send a new version and with mst@redhat.com
in the to, given it's fixes and where we are in the cycle they may get picked up sooner.

If you do that, 
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> 
for both patches

Whilst I don't think anything else I have queued touches this code, make sure
you base on upstream qemu.

Thanks,

Jonathan



>          count++;
>      }
>