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From: Tim Chen <tim.c.chen@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jikos@kernel.org>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	David Woodhouse <dwmw@amazon.co.uk>,
	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>,
	linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [Patch v4 08/18] sched: Deprecate sched_smt_present and use cpu_smt_enabled static key
Date: Fri, 9 Nov 2018 14:08:43 -0800	[thread overview]
Message-ID: <e6b4af48-d848-8567-5927-745bbf6a388b@linux.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1811031914470.3160@nanos.tec.linutronix.de>

Thomas,

> 
>> The cpu_smt_enabled static key serves identical purpose as cpu_smt_enabled
> 
> That doesn't make any sense.
> 
>> to enable SMT specific code.
>>
>> This patch replaces sched_smt_present in the scheduler with
>> cpu_smt_enabled and deprecate sched_smt_present.
> 
> It's not deprecating it, it's replacing and removing it and thereby
> breaking all architectures which select SCHED_SMT except x86.

But the cpu_smt_enabled key is not x86 specific.  It is set and
defined in generic kernel/cpu.c and include/linux/cpu.h and available
for all architectures.

Why would it break other architectures?  I am missing something?

Thanks.

Tim

  reply	other threads:[~2018-11-09 22:08 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-30 18:49 [Patch v4 00/18] Provide process property based options to enable Spectre v2 userspace-userspace protection* Tim Chen
2018-10-30 18:49 ` [Patch v4 01/18] x86/speculation: Clean up spectre_v2_parse_cmdline() Tim Chen
2018-10-30 18:49 ` [Patch v4 02/18] x86/speculation: Remove unnecessary ret variable in cpu_show_common() Tim Chen
2018-10-30 18:49 ` [Patch v4 03/18] x86/speculation: Reorganize cpu_show_common() Tim Chen
2018-11-03 18:07   ` Thomas Gleixner
2018-11-05 19:12     ` Tim Chen
2018-11-05 19:17       ` Thomas Gleixner
2018-10-30 18:49 ` [Patch v4 04/18] x86/speculation: Add X86_FEATURE_USE_IBRS_ENHANCED Tim Chen
2018-10-30 18:49 ` [Patch v4 05/18] x86/speculation: Disable STIBP when enhanced IBRS is in use Tim Chen
2018-10-30 18:49 ` [Patch v4 06/18] smt: Create cpu_smt_enabled static key for SMT specific code Tim Chen
2018-10-30 18:49 ` [Patch v4 07/18] x86/smt: Convert cpu_smt_control check to cpu_smt_enabled static key Tim Chen
2018-11-03 18:29   ` Thomas Gleixner
2018-11-08  1:43     ` Tim Chen
2018-11-08 11:18       ` Thomas Gleixner
2018-10-30 18:49 ` [Patch v4 08/18] sched: Deprecate sched_smt_present and use " Tim Chen
2018-11-03 18:20   ` Thomas Gleixner
2018-11-09 22:08     ` Tim Chen [this message]
2018-10-30 18:49 ` [Patch v4 09/18] x86/speculation: Rename SSBD update functions Tim Chen
2018-10-30 18:49 ` [Patch v4 10/18] x86/speculation: Reorganize speculation control MSRs update Tim Chen
2018-10-30 18:49 ` [Patch v4 11/18] x86/speculation: Update comment on TIF_SSBD Tim Chen
2018-10-30 18:49 ` [Patch v4 12/18] x86: Group thread info flags by functionality Tim Chen
2018-10-30 18:49 ` [Patch v4 13/18] security: Update security level of a process when modifying its dumpability Tim Chen
2018-10-30 20:57   ` Schaufler, Casey
2018-10-30 21:30     ` Tim Chen
2018-10-30 21:53       ` Schaufler, Casey
2018-10-30 18:49 ` [Patch v4 14/18] x86/speculation: Turn on or off STIBP according to a task's TIF_STIBP Tim Chen
2018-10-30 18:49 ` [Patch v4 15/18] x86/speculation: Add Spectre v2 app to app protection modes Tim Chen
2018-10-30 18:49 ` [Patch v4 16/18] x86/speculation: Enable STIBP to protect security sensitive tasks Tim Chen
2018-10-30 21:07   ` Schaufler, Casey
2018-10-30 21:34     ` Tim Chen
2018-10-30 22:02       ` Schaufler, Casey
2018-10-30 18:49 ` [Patch v4 17/18] x86/speculation: Update SPEC_CTRL MSRs of remote CPUs Tim Chen
2018-11-04 19:49   ` Thomas Gleixner
2018-11-05 22:02     ` Tim Chen
2018-11-05 23:04       ` Thomas Gleixner
2018-11-05 23:59         ` Tim Chen
2018-11-06  7:46           ` Thomas Gleixner
2018-11-07  0:18             ` Tim Chen
2018-11-07 18:33               ` Waiman Long
2018-11-07 23:15                 ` Tim Chen
2018-11-07 23:03               ` Thomas Gleixner
2018-11-08  0:22                 ` Tim Chen
2018-10-30 18:49 ` [Patch v4 18/18] x86/speculation: Create PRCTL interface to restrict indirect branch speculation Tim Chen

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