From: Thomas Gleixner <tglx@linutronix.de> To: LKML <linux-kernel@vger.kernel.org> Cc: x86@kernel.org, Peter Zijlstra <peterz@infradead.org>, Andy Lutomirski <luto@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, Jiri Kosina <jkosina@suse.cz>, Tom Lendacky <thomas.lendacky@amd.com>, Josh Poimboeuf <jpoimboe@redhat.com>, Andrea Arcangeli <aarcange@redhat.com>, David Woodhouse <dwmw@amazon.co.uk>, Tim Chen <tim.c.chen@linux.intel.com>, Andi Kleen <ak@linux.intel.com>, Dave Hansen <dave.hansen@intel.com>, Casey Schaufler <casey.schaufler@intel.com>, Asit Mallick <asit.k.mallick@intel.com>, Arjan van de Ven <arjan@linux.intel.com>, Jon Masters <jcm@redhat.com>, Waiman Long <longman9394@gmail.com>, Greg KH <gregkh@linuxfoundation.org>, Dave Stewart <david.c.stewart@intel.com>, Kees Cook <keescook@chromium.org> Subject: [patch V2 08/28] sched/smt: Make sched_smt_present track topology Date: Sun, 25 Nov 2018 19:33:36 +0100 Message-ID: <20181125185004.246110444@linutronix.de> (raw) In-Reply-To: <20181125183328.318175777@linutronix.de> [-- Attachment #0: sched-smt-Make-sched-smt-present-track-topology.patch --] [-- Type: text/plain, Size: 1871 bytes --] Currently the 'sched_smt_present' static key is enabled when at CPU bringup SMT topology is observed, but it is never disabled. However there is demand to also disable the key when the topology changes such that there is no SMT present anymore. Implement this by making the key count the number of cores that have SMT enabled. In particular, the SMT topology bits are set before interrrupts are enabled and similarly, are cleared after interrupts are disabled for the last time and the CPU dies. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- kernel/sched/core.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5738,15 +5738,10 @@ int sched_cpu_activate(unsigned int cpu) #ifdef CONFIG_SCHED_SMT /* - * The sched_smt_present static key needs to be evaluated on every - * hotplug event because at boot time SMT might be disabled when - * the number of booted CPUs is limited. - * - * If then later a sibling gets hotplugged, then the key would stay - * off and SMT scheduling would never be functional. + * When going up, increment the number of cores with SMT present. */ - if (cpumask_weight(cpu_smt_mask(cpu)) > 1) - static_branch_enable_cpuslocked(&sched_smt_present); + if (cpumask_weight(cpu_smt_mask(cpu)) == 2) + static_branch_inc_cpuslocked(&sched_smt_present); #endif set_cpu_active(cpu, true); @@ -5790,6 +5785,14 @@ int sched_cpu_deactivate(unsigned int cp */ synchronize_rcu_mult(call_rcu, call_rcu_sched); +#ifdef CONFIG_SCHED_SMT + /* + * When going down, decrement the number of cores with SMT present. + */ + if (cpumask_weight(cpu_smt_mask(cpu)) == 2) + static_branch_dec_cpuslocked(&sched_smt_present); +#endif + if (!sched_smp_initialized) return 0;
next prev parent reply index Thread overview: 112+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-25 18:33 [patch V2 00/28] x86/speculation: Remedy the STIBP/IBPB overhead Thomas Gleixner 2018-11-25 18:33 ` [patch V2 01/28] x86/speculation: Update the TIF_SSBD comment Thomas Gleixner 2018-11-28 14:20 ` [tip:x86/pti] " tip-bot for Tim Chen 2018-11-29 14:27 ` [patch V2 01/28] " Konrad Rzeszutek Wilk 2018-11-25 18:33 ` [patch V2 02/28] x86/speculation: Clean up spectre_v2_parse_cmdline() Thomas Gleixner 2018-11-28 14:20 ` [tip:x86/pti] " tip-bot for Tim Chen 2018-11-29 14:28 ` [patch V2 02/28] " Konrad Rzeszutek Wilk 2018-11-25 18:33 ` [patch V2 03/28] x86/speculation: Remove unnecessary ret variable in cpu_show_common() Thomas Gleixner 2018-11-28 14:21 ` [tip:x86/pti] " tip-bot for Tim Chen 2018-11-29 14:28 ` [patch V2 03/28] " Konrad Rzeszutek Wilk 2018-11-25 18:33 ` [patch V2 04/28] x86/speculation: Reorganize cpu_show_common() Thomas Gleixner 2018-11-26 15:08 ` Borislav Petkov 2018-11-28 14:22 ` [tip:x86/pti] x86/speculation: Move STIPB/IBPB string conditionals out of cpu_show_common() tip-bot for Tim Chen 2018-11-29 14:29 ` [patch V2 04/28] x86/speculation: Reorganize cpu_show_common() Konrad Rzeszutek Wilk 2018-11-25 18:33 ` [patch V2 05/28] x86/speculation: Disable STIBP when enhanced IBRS is in use Thomas Gleixner 2018-11-28 14:22 ` [tip:x86/pti] " tip-bot for Tim Chen 2018-11-29 14:35 ` [patch V2 05/28] " Konrad Rzeszutek Wilk 2018-11-25 18:33 ` [patch V2 06/28] x86/speculation: Rename SSBD update functions Thomas Gleixner 2018-11-26 15:24 ` Borislav Petkov 2018-11-28 14:23 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-29 14:37 ` [patch V2 06/28] " Konrad Rzeszutek Wilk 2018-11-25 18:33 ` [patch V2 07/28] x86/speculation: Reorganize speculation control MSRs update Thomas Gleixner 2018-11-26 15:47 ` Borislav Petkov 2018-11-28 14:23 ` [tip:x86/pti] " tip-bot for Tim Chen 2018-11-29 14:41 ` [patch V2 07/28] " Konrad Rzeszutek Wilk 2018-11-25 18:33 ` Thomas Gleixner [this message] 2018-11-28 14:24 ` [tip:x86/pti] sched/smt: Make sched_smt_present track topology tip-bot for Peter Zijlstra (Intel) 2018-11-29 14:42 ` [patch V2 08/28] " Konrad Rzeszutek Wilk 2018-11-29 14:50 ` Konrad Rzeszutek Wilk 2018-11-29 15:48 ` Peter Zijlstra 2018-11-25 18:33 ` [patch V2 09/28] x86/Kconfig: Select SCHED_SMT if SMP enabled Thomas Gleixner 2018-11-28 14:24 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-29 14:44 ` [patch V2 09/28] " Konrad Rzeszutek Wilk 2018-11-25 18:33 ` [patch V2 10/28] sched/smt: Expose sched_smt_present static key Thomas Gleixner 2018-11-28 14:25 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-29 14:44 ` [patch V2 10/28] " Konrad Rzeszutek Wilk 2018-11-25 18:33 ` [patch V2 11/28] x86/speculation: Rework SMT state change Thomas Gleixner 2018-11-28 14:26 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 12/28] x86/l1tf: Show actual SMT state Thomas Gleixner 2018-11-28 14:26 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 13/28] x86/speculation: Reorder the spec_v2 code Thomas Gleixner 2018-11-26 22:21 ` Borislav Petkov 2018-11-28 14:27 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 14/28] x86/speculation: Mark string arrays const correctly Thomas Gleixner 2018-11-28 14:27 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 15/28] x86/speculataion: Mark command line parser data __initdata Thomas Gleixner 2018-11-28 14:28 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 16/28] x86/speculation: Unify conditional spectre v2 print functions Thomas Gleixner 2018-11-28 14:29 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 17/28] x86/speculation: Add command line control for indirect branch speculation Thomas Gleixner 2018-11-28 14:29 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 18/28] x86/speculation: Prepare for per task indirect branch speculation control Thomas Gleixner 2018-11-27 17:25 ` Lendacky, Thomas 2018-11-27 19:51 ` Tim Chen 2018-11-28 9:39 ` Thomas Gleixner 2018-11-27 20:39 ` Thomas Gleixner 2018-11-27 20:42 ` Thomas Gleixner 2018-11-27 21:52 ` Lendacky, Thomas 2018-11-28 14:30 ` [tip:x86/pti] " tip-bot for Tim Chen 2018-11-25 18:33 ` [patch V2 19/28] x86/process: Consolidate and simplify switch_to_xtra() code Thomas Gleixner 2018-11-26 18:30 ` Borislav Petkov 2018-11-28 14:30 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 20/28] x86/speculation: Avoid __switch_to_xtra() calls Thomas Gleixner 2018-11-28 14:31 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 21/28] x86/speculation: Prepare for conditional IBPB in switch_mm() Thomas Gleixner 2018-11-25 19:11 ` Thomas Gleixner 2018-11-25 20:53 ` Andi Kleen 2018-11-25 22:20 ` Thomas Gleixner 2018-11-25 23:04 ` Andy Lutomirski 2018-11-26 7:10 ` Thomas Gleixner 2018-11-26 13:36 ` Ingo Molnar 2018-11-26 3:07 ` Andi Kleen 2018-11-26 6:50 ` Thomas Gleixner 2018-11-28 14:31 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 22/28] ptrace: Remove unused ptrace_may_access_sched() and MODE_IBRS Thomas Gleixner 2018-11-28 14:32 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 23/28] x86/speculation: Split out TIF update Thomas Gleixner 2018-11-28 14:33 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 24/28] x86/speculation: Prepare arch_smt_update() for PRCTL mode Thomas Gleixner 2018-11-27 20:18 ` Lendacky, Thomas 2018-11-27 20:30 ` Thomas Gleixner 2018-11-27 21:20 ` Lendacky, Thomas 2018-11-28 14:34 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 25/28] x86/speculation: Add prctl() control for indirect branch speculation Thomas Gleixner 2018-11-28 14:34 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 26/28] x86/speculation: Enable prctl mode for spectre_v2_user Thomas Gleixner 2018-11-26 7:56 ` Dominik Brodowski 2018-11-28 14:35 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-25 18:33 ` [patch V2 27/28] x86/speculation: Add seccomp Spectre v2 user space protection mode Thomas Gleixner 2018-11-25 19:35 ` Randy Dunlap 2018-11-25 20:40 ` Linus Torvalds 2018-11-25 20:52 ` Jiri Kosina 2018-11-25 22:28 ` Thomas Gleixner 2018-11-26 13:30 ` Ingo Molnar 2018-11-26 20:48 ` Andrea Arcangeli 2018-11-26 20:58 ` Thomas Gleixner 2018-11-26 21:52 ` Lendacky, Thomas 2018-11-27 0:37 ` Tim Chen 2018-12-04 1:38 ` Tim Chen 2018-12-04 8:39 ` Jiri Kosina 2018-12-04 9:43 ` Arjan van de Ven 2018-12-04 9:46 ` Arjan van de Ven 2018-12-04 17:20 ` Linus Torvalds 2018-12-04 18:58 ` Tim Chen 2018-11-28 14:35 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-12-04 18:45 ` [patch V2 27/28] " Dave Hansen 2018-11-25 18:33 ` [patch V2 28/28] x86/speculation: Provide IBPB always command line options Thomas Gleixner 2018-11-28 14:36 ` [tip:x86/pti] " tip-bot for Thomas Gleixner 2018-11-26 13:37 ` [patch V2 00/28] x86/speculation: Remedy the STIBP/IBPB overhead Ingo Molnar 2018-11-28 14:24 ` Thomas Gleixner 2018-11-29 19:02 ` Tim Chen 2018-12-10 23:43 ` Pavel Machek
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