Re: [PATCH RFC 08/19] RISC-V: QoS: add resctrl interface for CBQRI controllers

Hi Drew,

On Thu, Jan 29, 2026 at 4:28 AM Drew Fustini <[email protected]> wrote:>
> Add interface for CBQRI controller drivers to make use of the resctrl
> filesystem.
>
> Co-developed-by: Adrien Ricciardi <[email protected]>
> Signed-off-by: Adrien Ricciardi <[email protected]>
> Signed-off-by: Drew Fustini <[email protected]>
> ---
>  arch/riscv/kernel/qos/qos_resctrl.c | 1192 +++++++++++++++++++++++++++++++++++
>  1 file changed, 1192 insertions(+)
>
> ...
>
> +
> +int resctrl_arch_update_one(struct rdt_resource *r, struct rdt_ctrl_domain *d,
> +                           u32 closid, enum resctrl_conf_type t, u32 cfg_val)
> +{
> +       struct cbqri_controller *ctrl;
> +       struct cbqri_resctrl_dom *dom;
> +       struct cbqri_config cfg;
> +       int err = 0;
> +
> +       dom = container_of(d, struct cbqri_resctrl_dom, resctrl_ctrl_dom);
> +       ctrl = dom->hw_ctrl;
> +
> +       if (!r->alloc_capable)
> +               return -EINVAL;
> +
> +       switch (r->rid) {
> +       case RDT_RESOURCE_L2:
> +       case RDT_RESOURCE_L3:
> +               cfg.cbm = cfg_val;
> +               err = cbqri_apply_cache_config(dom, closid, t, &cfg);
> +               break;
> +       case RDT_RESOURCE_MBA:
> +               /* covert from percentage to bandwidth blocks */
> +               cfg.rbwb = cfg_val * ctrl->bc.nbwblks / 100;

Should use bc.mrbwb to calculate rbwb? 
I think bc.nbwblks represent the available bw blks in the controller. It should should decrease as they are allocated.

> +               err = cbqri_apply_bw_config(dom, closid, t, &cfg);
> +               break;
> +       default:
> +               return -EINVAL;
> +       }
> +
> +       return err;
> +}
>
> ...
>
> +u32 resctrl_arch_get_config(struct rdt_resource *r, struct rdt_ctrl_domain *d,
> +                           u32 closid, enum resctrl_conf_type type)
> +{
> +       struct cbqri_resctrl_dom *hw_dom;
> +       struct cbqri_controller *ctrl;
> +       int reg_offset;
> +       u32 percent;
> +       u32 rbwb;
> +       u64 reg;
> +       int err;
> +
> +       hw_dom = container_of(d, struct cbqri_resctrl_dom, resctrl_ctrl_dom);
> +
> +       ctrl = hw_dom->hw_ctrl;
> +
> +       if (!r->alloc_capable)
> +               return resctrl_get_default_ctrl(r);
> +
> +       switch (r->rid) {
> +       case RDT_RESOURCE_L2:
> +       case RDT_RESOURCE_L3:
> +               /* Clear cc_block_mask before read limit operation */
> +               cbqri_set_cbm(ctrl, 0);
> +
> +               /* Capacity read limit operation for RCID (closid) */
> +               err = cbqri_cc_alloc_op(ctrl, CBQRI_CC_ALLOC_CTL_OP_READ_LIMIT, type, closid);
> +               if (err < 0) {
> +                       pr_err("%s(): operation failed: err = %d", __func__, err);
> +                       return resctrl_get_default_ctrl(r);
> +               }
> +
> +               /* Read capacity block mask for RCID (closid) */
> +               reg_offset = CBQRI_CC_BLOCK_MASK_OFF;
> +               reg = ioread64(ctrl->base + reg_offset);
> +
> +               /* Update the config value for the closid in this domain */
> +               hw_dom->ctrl_val[closid] = reg;
> +               return hw_dom->ctrl_val[closid];
> +
> +       case RDT_RESOURCE_MBA:
> +               /* Capacity read limit operation for RCID (closid) */
> +               err = cbqri_bc_alloc_op(ctrl, CBQRI_CC_ALLOC_CTL_OP_READ_LIMIT, closid);
> +               if (err < 0) {
> +                       pr_err("%s(): operation failed: err = %d", __func__, err);
> +                       return resctrl_get_default_ctrl(r);
> +               }
> +
> +               hw_dom->ctrl_val[closid] = cbqri_get_rbwb(ctrl);
> +
> +               /* Convert from bandwidth blocks to percent */
> +               rbwb = hw_dom->ctrl_val[closid];
> +               rbwb *= 100;
> +               percent = rbwb / ctrl->bc.nbwblks;
> +               if (rbwb % ctrl->bc.nbwblks)

Same problem.

> +                       percent++;
> +               return percent;
> +
> +       default:
> +               return resctrl_get_default_ctrl(r);
> +       }
> +}


Thank,
Wenjia