Re: [PATCH 14/33] arm_mpam: Probe hardware to find the supported partid/pmg values

Fenghua Yu
2025-11-13T03:50:47Z

Hi, Ben and James,

On 11/7/25 04:34, Ben Horgan wrote:
> From: James Morse <james.morse@arm.com>
[SNIP]

> +static struct mpam_msc_ris *mpam_get_or_create_ris(struct mpam_msc *msc,
> + u8 ris_idx)
> +{
> + int err;
> + struct mpam_msc_ris *ris;
> +
> + lockdep_assert_held(&mpam_list_lock);
> +
> + if (!test_bit(ris_idx, &msc->ris_idxs)) {
> + err = mpam_ris_create_locked(msc, ris_idx, MPAM_CLASS_UNKNOWN,
> + 0, 0);
> + if (err)
> + return ERR_PTR(err);
> + }
> +
> + list_for_each_entry(ris, &msc->ris, msc_list) {
> + if (ris->ris_idx == ris_idx)
> + return ris;
> + }
> +
> + return ERR_PTR(-ENOENT);
> +}
> +
> static int mpam_msc_hw_probe(struct mpam_msc *msc)
> {
> u64 idr;
> + u16 partid_max;
> + u8 ris_idx, pmg_max;
> + struct mpam_msc_ris *ris;
> struct device *dev = &msc->pdev->dev;
>
> lockdep_assert_held(&msc->probe_lock);
> @@ -464,6 +564,40 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)
> return -EIO;
> }
>
> + /* Grab an IDR value to find out how many RIS there are */
> + mutex_lock(&msc->part_sel_lock);
> + idr = mpam_msc_read_idr(msc);
> + mutex_unlock(&msc->part_sel_lock);
> +
> + msc->ris_max = FIELD_GET(MPAMF_IDR_RIS_MAX, idr);
> +
> + /* Use these values so partid/pmg always starts with a valid value */
> + msc->partid_max = FIELD_GET(MPAMF_IDR_PARTID_MAX, idr);
> + msc->pmg_max = FIELD_GET(MPAMF_IDR_PMG_MAX, idr);
> +
> + for (ris_idx = 0; ris_idx <= msc->ris_max; ris_idx++) {
> + mutex_lock(&msc->part_sel_lock);
> + __mpam_part_sel(ris_idx, 0, msc);
> + idr = mpam_msc_read_idr(msc);
> + mutex_unlock(&msc->part_sel_lock);
> +
> + partid_max = FIELD_GET(MPAMF_IDR_PARTID_MAX, idr);
> + pmg_max = FIELD_GET(MPAMF_IDR_PMG_MAX, idr);
> + msc->partid_max = min(msc->partid_max, partid_max);
> + msc->pmg_max = min(msc->pmg_max, pmg_max);
> +
> + mutex_lock(&mpam_list_lock);
> + ris = mpam_get_or_create_ris(msc, ris_idx);
> + mutex_unlock(&mpam_list_lock);
> + if (IS_ERR(ris))
> + return PTR_ERR(ris);

It's better to destroy ris's that were previously created before this
failed ris? Otherwise, there is a memory leak for those allocated ris's?

Thanks.

-Fenghua