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Message-ID: <a0800b06-030e-4aba-ad8e-937d4efa4804@intel.com>
Date: Tue, 8 Jul 2025 19:38:18 -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>, Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
Chen Yu <yu.c.chen@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
<patches@...ts.linux.dev>
Subject: Re: [PATCH v6 19/30] x86/resctrl: Complete telemetry event
enumeration
Hi Tony,
On 6/26/25 9:49 AM, Tony Luck wrote:
> Counters for telemetry events are in MMIO space. Each telemetry_region
> structure returned in the pmt_feature_group returned from OOBMSM contains
> the base MMIO address for the counters.
>
> Scan all the telemetry_region structures again and save the number
> of regions together with a flex array of the mmio addresses for each
mmio -> MMIO
> aggregator indexed by package id. Note that there may be multiple
> aggregators per package.
This final "note" seems redundant considering the paragraph
reads: "Scan all the telemetry_region structures (plural) again and
save the number of regions (plural) ..." Perhaps just rework the
paragraph to read:
There may be multiple aggregators per package. Scan all the
telemetry_region structures ...
>
> Completed structure for each event group looks like this:
>
> +---------------------+---------------------+
> pkginfo** -->| pkginfo[0] | pkginfo[1] |
since there are multiple arrays in this depiction it can be made
specific with a:
| pkginfo[package ID 0] | pkginfo[package ID 1] |
> +---------------------+---------------------+
> | |
> v v
> +----------------+ +----------------+
> |struct mmio_info| |struct mmio_info|
> +----------------+ +----------------+
> |num_regions = N | |num_regions = N |
> | addrs[0] | | addrs[0] |
> | addrs[1] | | addrs[1] |
> | ... | | ... |
> | addrs[N-1] | | addrs[N-1] |
> +----------------+ +----------------+
>
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
> arch/x86/kernel/cpu/resctrl/intel_aet.c | 64 +++++++++++++++++++++++++
> 1 file changed, 64 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> index 8d67ed709a74..c770039b2525 100644
> --- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
> +++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> @@ -19,17 +19,32 @@
>
> #include "internal.h"
>
> +/**
> + * struct mmio_info - MMIO address information for one event group of a package.
> + * @num_regions: Number of telemetry regions on this package.
> + * @addrs: Array of MMIO addresses, one per telemetry region on this package.
> + *
> + * Provides convenient access to all MMIO addresses of one event group
> + * for one package. Used when reading event data on a package.
> + */
> +struct mmio_info {
This struct name is a bit generic. What do you think of "pkg_mmio_info" to
at least help describe it is per package?
> + int num_regions;
> + void __iomem *addrs[] __counted_by(num_regions);
> +};
> +
> /**
> * struct event_group - All information about a group of telemetry events.
> * @pfg: Points to the aggregated telemetry space information
> * within the OOBMSM driver that contains data for all
> * telemetry regions.
> + * @pkginfo: Per-package MMIO addresses of telemetry regions belonging to this group.
> * @guid: Unique number per XML description file.
> * @mmio_size: Number of bytes of MMIO registers for this group.
> */
> struct event_group {
> /* Data fields for additional structures to manage this group. */
> struct pmt_feature_group *pfg;
> + struct mmio_info **pkginfo;
>
> /* Remaining fields initialized from XML file. */
> u32 guid;
> @@ -81,6 +96,20 @@ static bool skip_this_region(struct telemetry_region *tr, struct event_group *e)
> return false;
> }
>
> +static void free_mmio_info(struct mmio_info **mmi)
> +{
> + int num_pkgs = topology_max_packages();
> +
> + if (!mmi)
> + return;
> +
> + for (int i = 0; i < num_pkgs; i++)
> + kfree(mmi[i]);
> + kfree(mmi);
> +}
> +
> +DEFINE_FREE(mmio_info, struct mmio_info **, free_mmio_info(_T))
> +
> /*
> * Configure events from one pmt_feature_group.
> * 1) Count how many per package.
(no update to the function comments)
> @@ -88,8 +117,10 @@ static bool skip_this_region(struct telemetry_region *tr, struct event_group *e)
> */
> static int configure_events(struct event_group *e, struct pmt_feature_group *p)
> {
> + struct mmio_info **pkginfo __free(mmio_info) = NULL;
> int *pkgcounts __free(kfree) = NULL;
> struct telemetry_region *tr;
> + struct mmio_info *mmi;
> int num_pkgs;
>
> num_pkgs = topology_max_packages();
> @@ -99,6 +130,12 @@ static int configure_events(struct event_group *e, struct pmt_feature_group *p)
> tr = &p->regions[i];
> if (skip_this_region(tr, e))
> continue;
> +
> + if (e->pkginfo) {
> + pr_warn_once("Duplicate telemetry information for guid 0x%x\n", e->guid);
> + return -EINVAL;
> + }
It does not seem necessary to repeat this check for every telemetry region. Could this check
be moved to start of function to avoid parsing struct pmt_feature_group entirely?
> +
> if (!pkgcounts) {
> pkgcounts = kcalloc(num_pkgs, sizeof(*pkgcounts), GFP_KERNEL);
> if (!pkgcounts)
> @@ -110,6 +147,32 @@ static int configure_events(struct event_group *e, struct pmt_feature_group *p)
> if (!pkgcounts)
> return -ENODEV;
>
> + /* Allocate array for per-package struct mmio_info data */
> + pkginfo = kcalloc(num_pkgs, sizeof(*pkginfo), GFP_KERNEL);
> + if (!pkginfo)
> + return -ENOMEM;
> +
> + /*
> + * Allocate per-package mmio_info structures and initialize
> + * count of telemetry_regions in each one.
> + */
> + for (int i = 0; i < num_pkgs; i++) {
> + pkginfo[i] = kzalloc(struct_size(pkginfo[i], addrs, pkgcounts[i]), GFP_KERNEL);
> + if (!pkginfo[i])
> + return -ENOMEM;
> + pkginfo[i]->num_regions = pkgcounts[i];
> + }
> +
> + /* Save MMIO address(es) for each telemetry region in per-package structures */
> + for (int i = 0; i < p->count; i++) {
> + tr = &p->regions[i];
> + if (skip_this_region(tr, e))
> + continue;
> + mmi = pkginfo[tr->plat_info.package_id];
> + mmi->addrs[--pkgcounts[tr->plat_info.package_id]] = tr->addr;
> + }
> + e->pkginfo = no_free_ptr(pkginfo);
> +
> return 0;
> }
>
> @@ -169,5 +232,6 @@ void __exit intel_aet_exit(void)
> intel_pmt_put_feature_group((*peg)->pfg);
> (*peg)->pfg = NULL;
> }
> + free_mmio_info((*peg)->pkginfo);
> }
> }
Reinette
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