linux-kernel - Re: [PATCH v2 11/16] x86/resctrl: Link known events onto RDT_RESOURCE_INTEL_AET.evt

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Message-ID: <10df8cbf-3b7c-461f-8a0d-bcc6b87444c0@intel.com>
Date: Mon, 31 Mar 2025 09:23:14 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghuay@...dia.com>, "Maciej
 Wieczor-Retman" <maciej.wieczor-retman@...el.com>, Peter Newman
	<peternewman@...gle.com>, James Morse <james.morse@....com>, Babu Moger
	<babu.moger@....com>, Drew Fustini <dfustini@...libre.com>, Dave Martin
	<Dave.Martin@....com>
CC: <linux-kernel@...r.kernel.org>, <patches@...ts.linux.dev>
Subject: Re: [PATCH v2 11/16] x86/resctrl: Link known events onto
 RDT_RESOURCE_INTEL_AET.evt_list

Hi Tony,

On 3/21/25 4:16 PM, Tony Luck wrote:
> Core code uses this list to populate "mon_data" directories.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>  arch/x86/kernel/cpu/resctrl/intel_aet.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> index e2d8eab997fc..9ac912742ef1 100644
> --- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
> +++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> @@ -13,6 +13,7 @@
>  
>  #include <linux/cpu.h>
>  #include <linux/cleanup.h>
> +#include <linux/minmax.h>
>  #include <linux/slab.h>
>  #include "fake_intel_aet_features.h"
>  #include <linux/intel_vsec.h>
> @@ -308,14 +309,34 @@ void rdt_get_intel_aet_mount(void)
>  {
>  	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_INTEL_AET].r_resctrl;
>  	struct rdt_core_mon_domain *d, *tmp;
> +	struct telem_entry **tentry;
>  	static int do_one_time;
> +	struct mon_evt *evt;
> +	bool ret = false;
>  
>  	if (do_one_time)
>  		return;
>  
>  	do_one_time = 1;
>  
> -	if (!get_events()) {
> +	if (!get_events())
> +		goto done;
> +
> +	for (tentry = telem_entry; *tentry; tentry++) {
> +		if (!(*tentry)->active)
> +			continue;
> +		for (int i = 0; (*tentry)->evts[i].evt.name; i++) {
> +			evt = &(*tentry)->evts[i].evt;
> +			list_add_tail(&evt->list, &r->evt_list);
> +			ret = true;
> +		}

Architecture code should not be doing this. I expect this will be something
similar to l3_mon_evt_init() done by fs code after the architecture had
opportunity to configure which events are supported. 
I wonder if resctrl_mon_resource_init() could be moved to rdt_get_tree()
to be called after the new (yet to be named) "resctrl_arch_for_arch_to_do_needed_on_resctrl_mount()"
resctrl_mon_resource_init() could be enhanced to do any needed resctrl fs
initialization for this new feature. This will include being able to 
learn the accurate counts of rmid supported by the system to be able to
create monitor groups that can be supported by all monitoring resources?

> +		if (!r->num_rmid)
> +			r->num_rmid = (*tentry)->num_rmids;
> +		else
> +			r->num_rmid = min(r->num_rmid, (*tentry)->num_rmids);
> +	}
> +done:
> +	if (!ret) {
>  		list_for_each_entry_safe(d, tmp, &r->mon_domains, hdr.list)
>  			kfree(d);
>  		r->mon_capable = false;

Reinette