Re: [PATCH v6 20/42] x86/resctrl: Change mon_event_config_{read,write}() to be arch helpers

["Moger, Babu" <babu.moger@amd.com>]

Hi James,

On 2/7/25 12:18, James Morse wrote:
> mon_event_config_{read,write}() are called via IPI and access model
> specific registers to do their work.
> 
> To support another architecture, this needs abstracting.
> 
> Rename mon_event_config_{read,write}() to have a "resctrl_arch_"
> prefix, and move their struct mon_config_info parameter into
> <linux/resctrl.h>.  This allows another architecture to supply an
> implementation of these.
> 
> As struct mon_config_info is now exposed globally, give it a 'resctrl_'
> prefix. MPAM systems need access to the domain to do this work, add
> the resource and domain to struct resctrl_mon_config_info.
> 
> Co-developed-by: Dave Martin <Dave.Martin@arm.com>
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> Signed-off-by: James Morse <james.morse@arm.com>
> Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
> Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
> Reviewed-by: Tony Luck <tony.luck@intel.com>
> ---
> Changes since v5:
>  * Renamed info to config_info.
>  * Added description of which fields are read and written in the structure.
>  * Clarified comment about which CPU this is called on for both kinds of
>    reader.
> 
> Changes since v3:
>  * Added comments over the read/write helper to explain the type of the void
>    pointer.
> 
> Changes since v1:
>  * [Whitespace only] Re-tabbed struct resctrl_mon_config_info in
>    <linux/resctrl.h> to fit the prevailing style.
> 
>    Non-functional change.
> 
>  * [Commit message only] Reword to align with the actual naming of the
>    definitions and destination header file.
> ---
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c | 46 +++++++++++++-------------
>  include/linux/resctrl.h                | 31 +++++++++++++++++
>  2 files changed, 54 insertions(+), 23 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index eb32fbc3abea..e7d1d8b6983d 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1580,11 +1580,6 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
>  	return ret;
>  }
>  
> -struct mon_config_info {
> -	u32 evtid;
> -	u32 mon_config;
> -};
> -
>  #define INVALID_CONFIG_INDEX   UINT_MAX
>  
>  /**
> @@ -1609,31 +1604,32 @@ static inline unsigned int mon_event_config_index_get(u32 evtid)
>  	}
>  }
>  
> -static void mon_event_config_read(void *info)
> +void resctrl_arch_mon_event_config_read(void *_config_info)
>  {
> -	struct mon_config_info *mon_info = info;
> +	struct resctrl_mon_config_info *config_info = _config_info;
>  	unsigned int index;
>  	u64 msrval;
>  
> -	index = mon_event_config_index_get(mon_info->evtid);
> +	index = mon_event_config_index_get(config_info->evtid);
>  	if (index == INVALID_CONFIG_INDEX) {
> -		pr_warn_once("Invalid event id %d\n", mon_info->evtid);
> +		pr_warn_once("Invalid event id %d\n", config_info->evtid);
>  		return;
>  	}
>  	rdmsrl(MSR_IA32_EVT_CFG_BASE + index, msrval);
>  
>  	/* Report only the valid event configuration bits */
> -	mon_info->mon_config = msrval & MAX_EVT_CONFIG_BITS;
> +	config_info->mon_config = msrval & MAX_EVT_CONFIG_BITS;
>  }
>  
> -static void mondata_config_read(struct rdt_mon_domain *d, struct mon_config_info *mon_info)
> +static void mondata_config_read(struct resctrl_mon_config_info *mon_info)
>  {
> -	smp_call_function_any(&d->hdr.cpu_mask, mon_event_config_read, mon_info, 1);
> +	smp_call_function_any(&mon_info->d->hdr.cpu_mask,
> +			      resctrl_arch_mon_event_config_read, mon_info, 1);
>  }
>  
>  static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid)
>  {
> -	struct mon_config_info mon_info;
> +	struct resctrl_mon_config_info mon_info;
>  	struct rdt_mon_domain *dom;
>  	bool sep = false;
>  
> @@ -1644,9 +1640,11 @@ static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid
>  		if (sep)
>  			seq_puts(s, ";");
>  
> -		memset(&mon_info, 0, sizeof(struct mon_config_info));
> +		memset(&mon_info, 0, sizeof(struct resctrl_mon_config_info));
> +		mon_info.r = r;
> +		mon_info.d = dom;
>  		mon_info.evtid = evtid;
> -		mondata_config_read(dom, &mon_info);
> +		mondata_config_read(&mon_info);
>  
>  		seq_printf(s, "%d=0x%02x", dom->hdr.id, mon_info.mon_config);
>  		sep = true;
> @@ -1679,30 +1677,32 @@ static int mbm_local_bytes_config_show(struct kernfs_open_file *of,
>  	return 0;
>  }
>  
> -static void mon_event_config_write(void *info)
> +void resctrl_arch_mon_event_config_write(void *_config_info)
>  {
> -	struct mon_config_info *mon_info = info;
> +	struct resctrl_mon_config_info *config_info = _config_info;
>  	unsigned int index;
>  
> -	index = mon_event_config_index_get(mon_info->evtid);
> +	index = mon_event_config_index_get(config_info->evtid);
>  	if (index == INVALID_CONFIG_INDEX) {
> -		pr_warn_once("Invalid event id %d\n", mon_info->evtid);
> +		pr_warn_once("Invalid event id %d\n", config_info->evtid);
>  		return;
>  	}
> -	wrmsr(MSR_IA32_EVT_CFG_BASE + index, mon_info->mon_config, 0);
> +	wrmsr(MSR_IA32_EVT_CFG_BASE + index, config_info->mon_config, 0);
>  }
>  
>  static void mbm_config_write_domain(struct rdt_resource *r,
>  				    struct rdt_mon_domain *d, u32 evtid, u32 val)
>  {
> -	struct mon_config_info mon_info = {0};
> +	struct resctrl_mon_config_info mon_info = {0};
>  
>  	/*
>  	 * Read the current config value first. If both are the same then
>  	 * no need to write it again.
>  	 */
> +	mon_info.r = r;
> +	mon_info.d = d;
>  	mon_info.evtid = evtid;
> -	mondata_config_read(d, &mon_info);
> +	mondata_config_read(&mon_info);
>  	if (mon_info.mon_config == val)
>  		return;
>  
> @@ -1714,7 +1714,7 @@ static void mbm_config_write_domain(struct rdt_resource *r,
>  	 * are scoped at the domain level. Writing any of these MSRs
>  	 * on one CPU is observed by all the CPUs in the domain.
>  	 */
> -	smp_call_function_any(&d->hdr.cpu_mask, mon_event_config_write,
> +	smp_call_function_any(&d->hdr.cpu_mask, resctrl_arch_mon_event_config_write,
>  			      &mon_info, 1);
>  
>  	/*
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 5c7b9760b63a..59d944e139f8 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -270,6 +270,13 @@ struct resctrl_cpu_defaults {
>  	u32 rmid;
>  };
>  
> +struct resctrl_mon_config_info {
> +	struct rdt_resource	*r;
> +	struct rdt_mon_domain	*d;
> +	u32			evtid;
> +	u32			mon_config;
> +};

Isn't this architecture specific definition?  Why is this in common
resctrl.h file.

> +
>  /**
>   * resctrl_arch_sync_cpu_closid_rmid() - Refresh this CPU's CLOSID and RMID.
>   *					 Call via IPI.
> @@ -311,6 +318,30 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
>  
>  bool __init resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
>  
> +/**
> + * resctrl_arch_mon_event_config_write() - Write the config for an event.
> + * @config_info: struct resctrl_mon_config_info describing the resource, domain
> + *		 and event.
> + *
> + * Reads resource, domain and eventid from @config_info and writes the
> + * event config_info->mon_config into hardware.
> + *
> + * Called via IPI to reach a CPU that is a member of the specified domain.
> + */
> +void resctrl_arch_mon_event_config_write(void *config_info);
> +
> +/**
> + * resctrl_arch_mon_event_config_read() - Read the config for an event.
> + * @config_info: struct resctrl_mon_config_info describing the resource, domain
> + *		 and event.
> + *
> + * Reads resource, domain and eventid from @config_info and reads the
> + * hardware config value into config_info->mon_config.
> + *
> + * Called via IPI to reach a CPU that is a member of the specified domain.
> + */
> +void resctrl_arch_mon_event_config_read(void *config_info);
> +
>  /*
>   * Update the ctrl_val and apply this config right now.
>   * Must be called on one of the domain's CPUs.

-- 
Thanks
Babu Moger