Hi Tony,
On 12/4/25 12:53 PM, Tony Luck wrote:
> Legacy resctrl features are enumerated by X86_FEATURE_* flags. These may be
> overridden by quirks to disable features in the case of errata. Users can
> use kernel command line options to either disable a feature, or to force
> enable a feature that was disabled by a quirk.
>
> A different approach is needed for hardware features that do not have an
> X86_FEATURE_* flag.
>
> Update the parse loop of the "rdt=" boot option with a call to intel_aet_option()
> to handles "perf" and "energy" options. Prefixing an option with "!" force
"to handles" -> "to handle"? ... although ... "Update the parse loop ... with a call to
intel_aet_option()" just describes what can be seen from the patch. Could this instead
describe on higher level what this code accomplishes? Consider, for example:
Update parsing of the "rdt=" boot parameter to call the telemetry driver
directly to handle new "perf" and "energy" options that controls activation
of telemetry monitoring of the named type. By itself a "perf" or "energy" option
controls the forced enabling or disabling (with ! prefix) of all event groups of
the named type. A ":guid" suffix allows for fine grain control per event group.
> disables a feature. A ":guid" suffix allows for fine grain control per-guid.
>
> Signed-off-by: Tony Luck <tony.luck@intel.com>
> ---
> .../admin-guide/kernel-parameters.txt | 7 +++-
> arch/x86/kernel/cpu/resctrl/internal.h | 2 ++
> arch/x86/kernel/cpu/resctrl/core.c | 2 ++
> arch/x86/kernel/cpu/resctrl/intel_aet.c | 34 +++++++++++++++++++
> 4 files changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 2b465eab41a1..cc9d2800abeb 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -6217,9 +6217,14 @@
> rdt= [HW,X86,RDT]
> Turn on/off individual RDT features. List is:
> cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
> - mba, smba, bmec, abmc, sdciae.
> + mba, smba, bmec, abmc, sdciae, energy[:guid],
> + perf[:guid].
> E.g. to turn on cmt and turn off mba use:
> rdt=cmt,!mba
> + To turn off all energy telemetry monitoring and ensure that
> + perf telemetry monitoring associated with guid 0x12345
> + is enabled use:
> + rdt=!energy,perf:0x12345
>
> reboot= [KNL]
> Format (x86 or x86_64):
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 3b228b241fb2..df09091f7c6c 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -236,6 +236,7 @@ void __exit intel_aet_exit(void);
> int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val);
> void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
> struct list_head *add_pos);
> +bool intel_aet_option(bool force_off, char *tok);
> #else
> static inline bool intel_aet_get_events(void) { return false; }
> static inline void __exit intel_aet_exit(void) { }
> @@ -246,6 +247,7 @@ static inline int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64
>
> static inline void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
> struct list_head *add_pos) { }
> +static inline bool intel_aet_option(bool force_off, char *tok) { return false; }
> #endif
>
> #endif /* _ASM_X86_RESCTRL_INTERNAL_H */
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index 283d653002a2..960974ffa866 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -820,6 +820,8 @@ static int __init set_rdt_options(char *str)
> force_off = *tok == '!';
> if (force_off)
> tok++;
> + if (intel_aet_option(force_off, tok))
> + continue;
> for (o = rdt_options; o < &rdt_options[NUM_RDT_OPTIONS]; o++) {
> if (strcmp(tok, o->name) == 0) {
> if (force_off)
> diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> index 8fcd72fca81f..fec4bb781f82 100644
> --- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
> +++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> @@ -59,6 +59,10 @@ struct pmt_event {
> * data for all telemetry regions of type @pfname.
> * Valid if the system supports the event group,
> * NULL otherwise.
> + * @force_off: True when "rdt" command line disables this @guid
> + * or architecture code disables this @guid.
"disables this @guid" is written twice. Even so, is the scope not event group? That is, would
it not be more accurate to say:
True when "rdt" command line or architecture disables this event group.
> + * @force_on: True when "rdt" command line overrides disable of
> + * this @guid.
"True when "rdt" command line overrides disable of this event group."?
> * @guid: Unique number per XML description file.
> * @mmio_size: Number of bytes of MMIO registers for this group.
> * @num_events: Number of events in this group.
> @@ -68,6 +72,7 @@ struct event_group {
> /* Data fields for additional structures to manage this group. */
> const char *pfname;
> struct pmt_feature_group *pfg;
> + bool force_off, force_on;
>
> /* Remaining fields initialized from XML file. */
> u32 guid;
> @@ -122,6 +127,32 @@ static struct event_group *known_event_groups[] = {
> _peg < &known_event_groups[ARRAY_SIZE(known_event_groups)]; \
> _peg++)
>
> +bool intel_aet_option(bool force_off, char *tok)
> +{
> + struct event_group **peg;
> + bool ret = false;
> + u32 guid = 0;
> + char *name;
> +
Could you please add a NULL check for tok?
> + name = strsep(&tok, ":");
> + if (tok && kstrtou32(tok, 16, &guid))
> + return false;
> +
> + for_each_event_group(peg) {
> + if (strcmp(name, (*peg)->pfname))
> + continue;
> + if (guid && (*peg)->guid != guid)
> + continue;
> + if (force_off)
> + (*peg)->force_off = true;
> + else
> + (*peg)->force_on = true;
> + ret = true;
> + }
> +
> + return ret;
> +}
> +
> /*
> * Clear the address field of regions that did not pass the checks in
> * skip_telem_region() so they will not be used by intel_aet_read_event().
> @@ -173,6 +204,9 @@ static bool enable_events(struct event_group *e, struct pmt_feature_group *p)
> struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
> int skipped_events = 0;
>
> + if (e->force_off)
> + return false;
> +
> if (!group_has_usable_regions(e, p))
> return false;
>
Reinette