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From: Borislav Petkov <bp@alien8.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Luck, Tony" <tony.luck@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	"Christopherson, Sean J" <sean.j.christopherson@intel.com>,
	Ingo Molnar <mingo@kernel.org>,
	"Yu, Fenghua" <fenghua.yu@intel.com>,
	Ingo Molnar <mingo@redhat.com>, H Peter Anvin <hpa@zytor.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
	linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>
Subject: Re: [PATCH v15] x86/split_lock: Enable split lock detection by kernel
Date: Sat, 25 Jan 2020 21:33:12 +0100	[thread overview]
Message-ID: <20200125203312.GE4369@zn.tnic> (raw)
In-Reply-To: <20200125201221.GZ11457@worktop.programming.kicks-ass.net>

On Sat, Jan 25, 2020 at 09:12:21PM +0100, Peter Zijlstra wrote:
> > Blame PeterZ for that. For now I'd like to add the duplicate inline function
> > and then clean up by putting it into some header file (and maybe hunting down
> > other places where it could be used).

Sounds like a good plan.

> Yeah, I copy/paste cobbled that together. I figured it was easier to
> 'borrow' something that worked and adapt it than try and write
> something new in a hurry.

Yeah.

> > Also some PeterZ code. As the comment implies we really shouldn't be able
> > to get here. This whole function should only be called on CPU models that
> > support the MSR ... but PeterZ is defending against the situation that sometimes
> > there are special SKUs with the same model number (since we may be here because
> > of an x86_match_cpu() hit, rather than the architectural enumeration check).
> 
> My thinking was Virt, virt likes to mess up all msr expectations.

My only worry is to have it written down why we're doing this so that it
can be changed/removed later, when we've forgotten all about split lock.
Because pretty often we look at a comment-less chunk of code and wonder,
"why the hell did we add this in the first place."

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply	other threads:[~2020-01-25 20:33 UTC|newest]

Thread overview: 145+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-21  0:53 [PATCH v10 0/6] Enable split lock detection for real time and debug Fenghua Yu
2019-11-21  0:53 ` [PATCH v10 1/6] x86/msr-index: Add two new MSRs Fenghua Yu
2019-11-21  0:53 ` [PATCH v10 2/6] x86/cpufeatures: Enumerate the IA32_CORE_CAPABILITIES MSR Fenghua Yu
2019-11-21  0:53 ` [PATCH v10 3/6] x86/split_lock: Enumerate split lock detection by " Fenghua Yu
2019-11-21  0:53 ` [PATCH v10 4/6] x86/split_lock: Enumerate split lock detection if the IA32_CORE_CAPABILITIES MSR is not supported Fenghua Yu
2019-11-21 22:07   ` Andy Lutomirski
2019-11-22  0:37     ` Fenghua Yu
2019-11-22  2:13       ` Andy Lutomirski
2019-11-22  9:46         ` Peter Zijlstra
2019-11-21  0:53 ` [PATCH v10 5/6] x86/split_lock: Handle #AC exception for split lock Fenghua Yu
2019-11-21 22:10   ` Andy Lutomirski
2019-11-21 23:14     ` Fenghua Yu
2019-11-21 23:12       ` Andy Lutomirski
2019-11-21  0:53 ` [PATCH v10 6/6] x86/split_lock: Enable split lock detection by kernel parameter Fenghua Yu
2019-11-21  6:04   ` Ingo Molnar
2019-11-21 13:01     ` Peter Zijlstra
2019-11-21 13:15       ` Peter Zijlstra
2019-11-21 21:51         ` Luck, Tony
2019-11-21 22:24           ` Andy Lutomirski
2019-11-21 22:29             ` Luck, Tony
2019-11-21 23:18               ` Andy Lutomirski
2019-11-21 23:53                 ` Fenghua Yu
2019-11-22  1:52                   ` Sean Christopherson
2019-11-22  2:21                     ` Andy Lutomirski
2019-11-22  2:39                       ` Xiaoyao Li
2019-11-22  2:57                         ` Andy Lutomirski
2019-11-21 23:55                 ` Luck, Tony
2019-11-22  0:55             ` Luck, Tony
2019-11-22 10:08           ` Peter Zijlstra
2019-11-21 16:14       ` Fenghua Yu
2019-11-21 17:14         ` Ingo Molnar
2019-11-21 17:35         ` Peter Zijlstra
2019-11-21 17:12       ` Ingo Molnar
2019-11-21 17:34         ` Luck, Tony
2019-11-22 10:51           ` Peter Zijlstra
2019-11-22 15:27             ` Peter Zijlstra
2019-11-22 17:22               ` Luck, Tony
2019-11-22 20:23                 ` Peter Zijlstra
2019-11-22 18:02               ` Luck, Tony
2019-11-22 20:23                 ` Peter Zijlstra
2019-11-22 20:42                   ` Fenghua Yu
2019-11-22 21:25                     ` Andy Lutomirski
2019-12-12  8:57                       ` Peter Zijlstra
2019-12-12 18:52                         ` Luck, Tony
2019-12-12 19:46                           ` Luck, Tony
2019-12-12 20:01                             ` Andy Lutomirski
2019-12-16 16:21                               ` David Laight
2019-11-22 18:44               ` Sean Christopherson
2019-11-22 20:30                 ` Peter Zijlstra
2019-11-23  0:30               ` Luck, Tony
2019-11-25 16:13                 ` Sean Christopherson
2019-12-02 18:20                   ` Luck, Tony
2019-12-12  8:59                   ` Peter Zijlstra
2020-01-10 19:24                     ` [PATCH v11] x86/split_lock: Enable split lock detection by kernel Luck, Tony
2020-01-14  5:55                       ` Sean Christopherson
2020-01-15 22:27                         ` Luck, Tony
2020-01-15 22:57                           ` Sean Christopherson
2020-01-15 23:48                             ` Luck, Tony
2020-01-22 18:55                             ` [PATCH v12] " Luck, Tony
2020-01-22 19:04                               ` Borislav Petkov
2020-01-22 20:03                                 ` Luck, Tony
2020-01-22 20:55                                   ` Borislav Petkov
2020-01-22 22:42                               ` Arvind Sankar
2020-01-22 22:52                                 ` Arvind Sankar
2020-01-22 23:24                                 ` Luck, Tony
2020-01-23  0:45                                   ` Arvind Sankar
2020-01-23  1:23                                     ` Luck, Tony
2020-01-23  4:21                                       ` Arvind Sankar
2020-01-23 17:15                                         ` Luck, Tony
2020-01-23  3:53                                     ` [PATCH v13] " Luck, Tony
2020-01-23  4:45                                       ` Arvind Sankar
2020-01-23 23:16                                         ` [PATCH v14] " Luck, Tony
2020-01-24 21:36                                           ` Thomas Gleixner
2020-01-25  2:47                                             ` [PATCH v15] " Luck, Tony
2020-01-25 10:44                                               ` Borislav Petkov
2020-01-25 19:55                                                 ` Luck, Tony
2020-01-25 20:12                                                   ` Peter Zijlstra
2020-01-25 20:33                                                     ` Borislav Petkov [this message]
2020-01-25 21:42                                                       ` Luck, Tony
2020-01-25 22:17                                                         ` Borislav Petkov
2020-01-25 20:29                                                   ` Borislav Petkov
2020-01-25 13:41                                               ` Thomas Gleixner
2020-01-25 22:07                                                 ` [PATCH v16] " Luck, Tony
2020-01-25 22:43                                                   ` Mark D Rustad
2020-01-25 23:10                                                     ` Luck, Tony
2020-01-26 17:27                                                       ` Mark D Rustad
2020-01-26 20:05                                                         ` [PATCH v17] " Luck, Tony
2020-01-29 12:31                                                           ` Thomas Gleixner
2020-01-29 15:24                                                           ` [tip: x86/cpu] " tip-bot2 for Peter Zijlstra (Intel)
2020-02-03 20:41                                                           ` [PATCH v17] " Sean Christopherson
2020-02-06  0:49                                                             ` [PATCH] x86/split_lock: Avoid runtime reads of the TEST_CTRL MSR Luck, Tony
2020-02-06  1:18                                                               ` Andy Lutomirski
2020-02-06 16:46                                                                 ` Luck, Tony
2020-02-06 19:37                                                                   ` Andy Lutomirski
2020-03-03 19:22                                                                     ` Sean Christopherson
2020-02-04  0:04                                                           ` [PATCH v17] x86/split_lock: Enable split lock detection by kernel Sean Christopherson
2020-02-04 12:52                                                             ` Thomas Gleixner
2020-01-26  0:34                                                   ` [PATCH v16] " Andy Lutomirski
2020-01-26 20:01                                                     ` Luck, Tony
2020-01-25 21:25                                               ` [PATCH v15] " Arvind Sankar
2020-01-25 21:50                                                 ` Luck, Tony
2020-01-25 23:51                                                   ` Arvind Sankar
2020-01-26  2:52                                                     ` Luck, Tony
2020-01-27  2:05                                                       ` Tony Luck
2020-01-27  8:04                                                   ` Peter Zijlstra
2020-01-27  8:36                                                     ` Peter Zijlstra
2020-01-27 17:35                                                     ` Luck, Tony
2020-01-27  8:02                                                 ` Peter Zijlstra
2019-12-13  0:09               ` [PATCH v11] x86/split_lock: Enable split lock detection by kernel parameter Tony Luck
2019-12-13  0:16                 ` Luck, Tony
2019-11-21 17:43         ` [PATCH v10 6/6] " David Laight
2019-11-21 17:51           ` Andy Lutomirski
2019-11-21 18:53             ` Fenghua Yu
2019-11-21 19:01               ` Andy Lutomirski
2019-11-21 20:25                 ` Fenghua Yu
2019-11-21 20:19                   ` Peter Zijlstra
2019-11-21 19:46               ` Peter Zijlstra
2019-11-21 20:25               ` Peter Zijlstra
2019-11-21 21:22                 ` Andy Lutomirski
2019-11-22  9:25                   ` Peter Zijlstra
2019-11-22 17:48                     ` Luck, Tony
2019-11-22 20:31                       ` Peter Zijlstra
2019-11-22 21:23                         ` Andy Lutomirski
2019-12-11 17:52                           ` Peter Zijlstra
2019-12-11 18:12                             ` Andy Lutomirski
2019-12-11 22:34                               ` Peter Zijlstra
2019-12-12 19:40                                 ` Andy Lutomirski
2019-12-16  9:59                                   ` David Laight
2019-12-16 17:22                                     ` Andy Lutomirski
2019-12-16 17:45                                       ` David Laight
2019-12-16 18:06                                         ` Andy Lutomirski
2019-12-17 10:03                                           ` David Laight
2019-12-11 18:44                             ` Luck, Tony
2019-12-11 22:39                               ` Peter Zijlstra
2019-12-12 10:36                                 ` David Laight
2019-12-12 13:04                                   ` Peter Zijlstra
2019-12-12 16:02                                     ` Andy Lutomirski
2019-12-12 16:23                                       ` David Laight
2019-12-12 16:29                                     ` David Laight
2019-11-21 19:56             ` Peter Zijlstra
2019-11-21 21:01               ` Andy Lutomirski
2019-11-22  9:36                 ` Peter Zijlstra
2019-11-22  9:46             ` David Laight
2019-11-22 20:32               ` Peter Zijlstra
2019-11-21  8:00   ` Peter Zijlstra

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