From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Linux PM <linux-pm@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Len Brown <len.brown@intel.com>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Aubrey Li <aubrey.li@linux.intel.com>,
Amit Kucheria <amitk@kernel.org>, Andi Kleen <ak@linux.intel.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Ricardo Neri <ricardo.neri@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/7] thermal: intel: hfi: Handle CPU hotplug events
Date: Thu, 2 Dec 2021 15:43:07 -0800 [thread overview]
Message-ID: <20211202234307.GA334@ranerica-svr.sc.intel.com> (raw)
In-Reply-To: <CAJZ5v0iXBn1o9ZFzNaYU4ft=JcRfNv7AJ8Sq-9HbBJbp60LpWQ@mail.gmail.com>
On Tue, Nov 30, 2021 at 02:32:42PM +0100, Rafael J. Wysocki wrote:
> On Tue, Nov 30, 2021 at 2:22 PM Ricardo Neri
> <ricardo.neri-calderon@linux.intel.com> wrote:
> >
> > On Wed, Nov 24, 2021 at 03:48:49PM +0100, Rafael J. Wysocki wrote:
> > > On Sat, Nov 6, 2021 at 2:34 AM Ricardo Neri
> > > <ricardo.neri-calderon@linux.intel.com> wrote:
>
> [cut]
>
> > > > +/**
> > > > + * intel_hfi_offline() - Disable HFI on @cpu
> > > > + * @cpu: CPU in which the HFI will be disabled
> > > > + *
> > > > + * Remove @cpu from those covered by its HFI instance.
> > > > + *
> > > > + * On some processors, hardware remembers previous programming settings even
> > > > + * after being reprogrammed. Thus, keep HFI enabled even if all CPUs in the
> > > > + * die/package of @cpu are offline. See note in intel_hfi_online().
> > > > + */
> > > > +void intel_hfi_offline(unsigned int cpu)
> > > > +{
> > > > + struct cpumask *die_cpumask = topology_core_cpumask(cpu);
> > > > + struct hfi_cpu_info *info = &per_cpu(hfi_cpu_info, cpu);
> > > > + struct hfi_instance *hfi_instance;
> > > > +
> > > > + if (!boot_cpu_has(X86_FEATURE_INTEL_HFI))
> > > > + return;
> > > > +
> > > > + hfi_instance = info->hfi_instance;
> > > > + if (!hfi_instance)
> > > > + return;
> > > > +
> > > > + if (!hfi_instance->initialized)
> > > > + return;
> > > > +
> > > > + mutex_lock(&hfi_lock);
> > > > +
> > > > + /*
> > > > + * We were using the core cpumask of @cpu to track CPUs in the same
> > > > + * die/package. Now it is going offline and we need to find another
> > > > + * CPU we can use.
> > > > + */
> > > > + if (die_cpumask == hfi_instance->cpus) {
> > > > + int new_cpu;
> > > > +
> > > > + new_cpu = cpumask_any_but(hfi_instance->cpus, cpu);
> > > > + if (new_cpu >= nr_cpu_ids)
> > > > + /* All other CPUs in the package are offline. */
> > > > + hfi_instance->cpus = NULL;
> > > > + else
> > > > + hfi_instance->cpus = topology_core_cpumask(new_cpu);
> > >
> > > Hmmm. Is topology_core_cpumask() updated when CPUs go offline and online?
> >
> > Yes. A CPU going offline is cleared from its siblings' cpumask [1] and its own [2]
> > in remove_siblinginfo() via cpu_disable_common(). A CPU going online is set
> > in its siblings' cpumask and its own in set_cpu_sibling_map() [3].
>
> OK, so it is necessary to ensure that intel_hfi_offline() will always
> run after remove_siblinginfo() so it sees the updated mask. How do we
> ensure that?
I don't think that is possible. remove_siblinginfo() is called from
CPUHP_TEARDOWN_CPU, which always happens after CPUHP_AP_OFFLINE, if I
understand correctly.
I guess that I will need to use a local cpumask as other drivers do.
Thanks and BR,
Ricardo
next prev parent reply other threads:[~2021-12-02 23:44 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-06 1:33 [PATCH 0/7] Thermal: Introduce the Hardware Feedback Interface for thermal and performance management Ricardo Neri
2021-11-06 1:33 ` [PATCH 1/7] x86/Documentation: Describe the Intel Hardware Feedback Interface Ricardo Neri
2021-11-30 9:24 ` Daniel Lezcano
2021-11-30 10:20 ` Srinivas Pandruvada
2021-11-06 1:33 ` [PATCH 2/7] x86: Add definitions for " Ricardo Neri
2021-11-06 10:30 ` Borislav Petkov
2021-11-06 22:01 ` Ricardo Neri
2021-11-06 1:33 ` [PATCH 3/7] thermal: intel: hfi: Minimally initialize the " Ricardo Neri
2021-11-08 8:47 ` Peter Zijlstra
2021-11-09 2:28 ` Ricardo Neri
2021-11-24 14:09 ` Rafael J. Wysocki
2021-11-30 3:20 ` Ricardo Neri
2021-11-30 3:55 ` Srinivas Pandruvada
2021-11-30 13:45 ` Ricardo Neri
2021-11-06 1:33 ` [PATCH 4/7] thermal: intel: hfi: Handle CPU hotplug events Ricardo Neri
2021-11-24 14:48 ` Rafael J. Wysocki
2021-11-30 13:21 ` Ricardo Neri
2021-11-30 13:32 ` Rafael J. Wysocki
2021-12-02 23:43 ` Ricardo Neri [this message]
2021-11-06 1:33 ` [PATCH 5/7] thermal: intel: hfi: Enable notification interrupt Ricardo Neri
2021-11-08 9:01 ` Peter Zijlstra
2021-11-09 15:00 ` Ricardo Neri
2021-11-08 9:07 ` Peter Zijlstra
2021-11-09 2:26 ` Ricardo Neri
2021-11-09 8:48 ` Peter Zijlstra
2021-11-09 12:54 ` Srinivas Pandruvada
2021-11-06 1:33 ` [PATCH 6/7] thermal: netlink: Add a new event to notify CPU capabilities change Ricardo Neri
2021-11-09 12:39 ` Lukasz Luba
2021-11-09 13:23 ` Srinivas Pandruvada
2021-11-09 13:53 ` Lukasz Luba
2021-11-09 14:15 ` Srinivas Pandruvada
2021-11-09 17:51 ` Lukasz Luba
2021-11-09 21:25 ` Srinivas Pandruvada
2021-11-30 9:29 ` Daniel Lezcano
2021-12-09 16:03 ` Ricardo Neri
2021-12-09 16:57 ` Daniel Lezcano
2021-12-09 17:39 ` Srinivas Pandruvada
2021-11-06 1:33 ` [PATCH 7/7] thermal: intel: hfi: Notify user space for HFI events Ricardo Neri
2021-11-24 15:18 ` Rafael J. Wysocki
2021-11-26 6:23 ` Srinivas Pandruvada
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