Re: [PATCH RFC v3 06/11] RISC-V: QoS: add resctrl setup and domain management

guo.wenjia23
2026-04-18T00:29:06Z

Hi Drew,

On Wed, Apr 15, 2026 at 9:57 AM Drew Fustini <fustini@kernel.org> wrote:

> Add the setup and domain management layer: domain allocation
> (qos_new_domain), controller value initialization
> (qos_init_domain_ctrlval), resource struct initialization for cache and
> bandwidth resources, domain registration with the resctrl filesystem
> (qos_resctrl_add_controller_domain), and the top-level setup function
> (qos_resctrl_setup) that probes all controllers and calls resctrl_init().
>
> Also add qos_resctrl_online_cpu() and qos_resctrl_offline_cpu() for CPU
> hotplug integration.
>
> Co-developed-by: Adrien Ricciardi <aricciardi@baylibre.com>
> Signed-off-by: Adrien Ricciardi <aricciardi@baylibre.com>
> Signed-off-by: Drew Fustini <fustini@kernel.org>
> ---
> arch/riscv/kernel/qos/qos_resctrl.c | 295 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 294 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/kernel/qos/qos_resctrl.c b/arch/riscv/kernel/qos/qos_resctrl.c
> index a4a120f89840..8d7e3b0abb75 100644
> --- a/arch/riscv/kernel/qos/qos_resctrl.c
> +++ b/arch/riscv/kernel/qos/qos_resctrl.c
> @@ -675,7 +675,23 @@ void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_l3_mon_domai
>
> void resctrl_arch_reset_all_ctrls(struct rdt_resource *r)
> {
> - /* not implemented for the RISC-V resctrl implementation */
> + struct cbqri_resctrl_res *hw_res;
> + struct rdt_ctrl_domain *d;
> + enum resctrl_conf_type t;
> + u32 default_ctrl;
> + int i;
> +
> + lockdep_assert_cpus_held();
> +
> + hw_res = container_of(r, struct cbqri_resctrl_res, resctrl_res);
> + default_ctrl = resctrl_get_default_ctrl(r);
> +
> + list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
> + for (i = 0; i < hw_res->max_rcid; i++) {
> + for (t = 0; t < CDP_NUM_TYPES; t++)
> + resctrl_arch_update_one(r, d, i, t, default_ctrl);

For the bw controller, default_ctrl = max_bw, and resctrl_arch_update_one will set the rbwb of all RCIDs to max_bw.
According to the spec: The sum of Rbwb allocated across all rcids must not exceed MRBWB value.

Does this conflict with the spec?

> + }
> + }
> }
>
> void resctrl_arch_pre_mount(void)
> @@ -797,3 +813,280 @@ u32 resctrl_arch_get_config(struct rdt_resource *r, struct rdt_ctrl_domain *d,
> spin_unlock(&ctrl->lock);
> return val;
> }
> +
> +static struct rdt_ctrl_domain *qos_new_domain(struct cbqri_controller *ctrl)
> +{
> + struct cbqri_resctrl_dom *hw_dom;
> + struct rdt_ctrl_domain *domain;
> +
> + hw_dom = kzalloc_obj(*hw_dom, GFP_KERNEL);
> + if (!hw_dom)
> + return NULL;
> +
> + /* associate this cbqri_controller with the domain */
> + hw_dom->hw_ctrl = ctrl;
> +
> + /* the rdt_domain struct from inside the cbqri_resctrl_dom struct */
> + domain = &hw_dom->resctrl_ctrl_dom;
> +
> + INIT_LIST_HEAD(&domain->hdr.list);
> +
> + return domain;
> +}
> +
> +static int qos_init_domain_ctrlval(struct rdt_resource *r, struct rdt_ctrl_domain *d)
> +{
> + struct cbqri_resctrl_res *hw_res;
> + int err = 0;
> + int i;
> +
> + hw_res = container_of(r, struct cbqri_resctrl_res, resctrl_res);
> +
> + for (i = 0; i < hw_res->max_rcid; i++) {
> + err = resctrl_arch_update_one(r, d, i, 0, resctrl_get_default_ctrl(r));

Also set rbwb of all RCIDs to max_bw. Does this also conflict with the spec?

> + if (err)
> + return err;
> + }
> + return 0;
> +}
> +

Thanks,
Wenjia