Re: [PATCH v1 10/20] x86/resctrl: Allow update_mba_bw() to update controls directly

[Reinette Chatre <reinette.chatre@intel.com>]

Hi James,

On 7/29/2021 3:36 PM, James Morse wrote:
> update_mba_bw() calculates a new control value for the MBA resource
> based on the user provided mbps_val and the current measured
> bandwidth. Some control values need remapping by delay_bw_map().
> 
> It does this by calling wrmsrl() directly. This needs splitting
> up to be done by an architecture specific helper, so that the
> remainder can eventually be moved to /fs/.
> 
> Add resctrl_arch_update_one() to apply one configuration value
> to the provided resource and domain. This avoids the staging
> and cross-calling that is only needed with changes made by
> user-space. delay_bw_map() moves to be part of the arch code,
> to maintain the 'percentage control' view of mba resources

mba -> MBA

> in resctrl.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
>   arch/x86/kernel/cpu/resctrl/core.c        |  2 +-
>   arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 21 +++++++++++++++++++++
>   arch/x86/kernel/cpu/resctrl/internal.h    |  1 -
>   arch/x86/kernel/cpu/resctrl/monitor.c     | 13 ++++---------
>   include/linux/resctrl.h                   |  8 ++++++++
>   5 files changed, 34 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index e864dbc6fe3d..8a3c13c6c19f 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -296,7 +296,7 @@ mba_wrmsr_amd(struct rdt_domain *d, struct msr_param *m, struct rdt_resource *r)
>    * that can be written to QOS_MSRs.
>    * There are currently no SKUs which support non linear delay values.
>    */
> -u32 delay_bw_map(unsigned long bw, struct rdt_resource *r)
> +static u32 delay_bw_map(unsigned long bw, struct rdt_resource *r)
>   {
>   	if (r->membw.delay_linear)
>   		return MAX_MBA_BW - bw;
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 56789ea11185..5104f39928fd 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -282,6 +282,27 @@ static bool apply_config(struct rdt_hw_domain *hw_dom,
>   	return false;
>   }
>   
> +int resctrl_arch_update_one(struct rdt_resource *r, struct rdt_domain *d,
> +			    u32 closid, enum resctrl_conf_type t, u32 cfg_val)
> +{
> +	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
> +	u32 idx = get_config_index(closid, t);
> +	struct msr_param msr_param;
> +
> +	if (!cpumask_test_cpu(smp_processor_id(), &d->cpu_mask))
> +		return -EINVAL;
> +
> +	hw_dom->ctrl_val[idx] = cfg_val;
> +
> +	msr_param.res = r;
> +	msr_param.low = idx;
> +	msr_param.high = idx + 1;
> +
> +	rdt_ctrl_update(&msr_param);
> +
> +	return 0;
> +}
> +
>   int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
>   {
>   	struct resctrl_staged_config *cfg;
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 796e13a0e8dc..1b07e49564cf 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -528,7 +528,6 @@ void mbm_handle_overflow(struct work_struct *work);
>   void __init intel_rdt_mbm_apply_quirk(void);
>   bool is_mba_sc(struct rdt_resource *r);
>   void setup_default_ctrlval(struct rdt_resource *r, u32 *dc);
> -u32 delay_bw_map(unsigned long bw, struct rdt_resource *r);
>   void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms);
>   void cqm_handle_limbo(struct work_struct *work);
>   bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d);
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index dcf3a73e2c17..b178329d3661 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -415,10 +415,8 @@ void mon_event_count(void *info)
>    */
>   static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm)
>   {
> -	u32 closid, rmid, cur_msr, cur_msr_val, new_msr_val;
> +	u32 closid, rmid, cur_msr_val, new_msr_val;
>   	struct mbm_state *pmbm_data, *cmbm_data;
> -	struct rdt_hw_resource *hw_r_mba;
> -	struct rdt_hw_domain *hw_dom_mba;
>   	u32 cur_bw, delta_bw, user_bw;
>   	struct rdt_resource *r_mba;
>   	struct rdt_domain *dom_mba;
> @@ -428,8 +426,8 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm)
>   	if (!is_mbm_local_enabled())
>   		return;
>   
> -	hw_r_mba = &rdt_resources_all[RDT_RESOURCE_MBA];
> -	r_mba = &hw_r_mba->r_resctrl;
> +	r_mba = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
> +
>   	closid = rgrp->closid;
>   	rmid = rgrp->mon.rmid;
>   	pmbm_data = &dom_mbm->mbm_local[rmid];
> @@ -439,7 +437,6 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm)
>   		pr_warn_once("Failure to get domain for MBA update\n");
>   		return;
>   	}
> -	hw_dom_mba = resctrl_to_arch_dom(dom_mba);
>   
>   	cur_bw = pmbm_data->prev_bw;
>   	user_bw = dom_mba->mba_sc[closid].mbps_val;
> @@ -481,9 +478,7 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm)
>   		return;
>   	}
>   
> -	cur_msr = hw_r_mba->msr_base + closid;
> -	wrmsrl(cur_msr, delay_bw_map(new_msr_val, r_mba));
> -	hw_dom_mba->ctrl_val[closid] = new_msr_val;
> +	resctrl_arch_update_one(r_mba, dom_mba, closid, CDP_NONE, new_msr_val);
>   

This can now fail ... but looks to be ok considering the earlier test.

>   	/*
>   	 * Delta values are updated dynamically package wise for each
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 3c8522d63261..4fe2d5500315 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -205,6 +205,14 @@ struct resctrl_schema {
>   /* The number of closid supported by this resource regardless of CDP */
>   u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
>   int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
> +
> +/*
> + * Update the ctrl_val and apply this config right now.
> + * Must be called on one of the domains cpus.

domains' CPUs

> + */
> +int resctrl_arch_update_one(struct rdt_resource *r, struct rdt_domain *d,
> +			    u32 closid, enum resctrl_conf_type t, u32 cfg_val);
> +
>   void resctrl_arch_get_config(struct rdt_resource *r, struct rdt_domain *d,
>   			     u32 closid, enum resctrl_conf_type type,
>   			     u32 *value);
> 

Reinette