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From: Sasha Levin <sashal@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Andi Kleen <ak@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	"Bae, Chang Seok" <chang.seok.bae@intel.com>,
	"Metzger, Markus T" <markus.t.metzger@intel.com>,
	"hpa@zytor.com" <hpa@zytor.com>, "bp@alien8.de" <bp@alien8.de>,
	"Hansen, Dave" <dave.hansen@intel.com>,
	"Luck, Tony" <tony.luck@intel.com>,
	Pedro Alves <palves@redhat.com>, Simon Marchi <simark@simark.ca>,
	"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v9 00/17] Enable FSGSBASE instructions
Date: Sat, 25 Apr 2020 22:52:43 -0400	[thread overview]
Message-ID: <20200426025243.GJ13035@sasha-vm> (raw)
In-Reply-To: <87ftcrtckg.fsf@nanos.tec.linutronix.de>

On Sun, Apr 26, 2020 at 12:39:27AM +0200, Thomas Gleixner wrote:
>Sasha Levin <sashal@kernel.org> writes:
>> On Wed, Apr 22, 2020 at 04:00:16PM -0700, Andy Lutomirski wrote:
>>>
>>>gdb and rr are certainly a good start.  If patches show up, I'll take a look.
>>
>> I'm sorry, but what patches are we talking about?
>
>About patches which:
>
>  - Are rebased to current upstream

v10 of this series was sent a few days ago and is rebased on top of
v5.7-rc1:
https://lore.kernel.org/lkml/20200423232207.5797-1-sashal@kernel.org/ .

>  - Addressed the outstanding review comments

I saw a review that Andy has just sent on patch #1 from the new series,
I'll address that.

>  - Have proper documentation in the changelog of the user space visible
>    ABI changes why it does not break any existing usage and having the
>    relevant people who maintain tools which utilize the affected
>    interfaces Cc'ed on submission.

The cover letter has references to mail correspondence with maintainers
of these tools that are affected by this change. Each of those exchanges
goes over what FSGSBASE does and answers any specific questions those
maintainers had.

If you want it out of the cover letter and into one of the patches I'd
be happy to do that. If you want me to go chase down another userspace
which we might be breaking just let me know which.

I didn't want to have them on the Cc line as they have already acked
this change from their end and I wanted to avoid additional noise. I'll
be happy to add them back to the next spin of this.

>  - Made sure that the cleanups I did when merging them initially have
>    been picked up. I'm not going to waste another couple of days on
>    this mess just to revert it because it hadn't seen any serious
>    testing in development.

Based on your revert
(https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=x86/cpu&id=049331f277fef1c3f2527c2c9afa1d285e9a1247)
I believe that we have all the relevant patches in the series.

I'll also add here that several groups at Microsoft have been running
workloads that heavily exercise the functionality added by this patch.
I'd say that it has gotten a solid round of testing for the past few
months.

-- 
Thanks,
Sasha

  reply	other threads:[~2020-04-26  2:52 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-04 18:15 Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 01/17] x86/ptrace: Prevent ptrace from clearing the FS/GS selector Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 02/17] selftests/x86/fsgsbase: Test GS selector on ptracer-induced GS base write Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 03/17] x86/cpu: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 04/17] x86/entry/64: Clean up paranoid exit Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 05/17] x86/entry/64: Switch CR3 before SWAPGS in paranoid entry Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 06/17] x86/entry/64: Introduce the FIND_PERCPU_BASE macro Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 07/17] x86/entry/64: Handle FSGSBASE enabled paranoid entry/exit Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 08/17] x86/entry/64: Document GSBASE handling in the paranoid path Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 09/17] x86/fsgsbase/64: Add intrinsics for FSGSBASE instructions Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 10/17] x86/fsgsbase/64: Enable FSGSBASE instructions in helper functions Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 11/17] x86/fsgsbase/64: Use FSGSBASE in switch_to() if available Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 12/17] x86/fsgsbase/64: Use FSGSBASE instructions on thread copy and ptrace Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 13/17] x86/speculation/swapgs: Check FSGSBASE in enabling SWAPGS mitigation Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 14/17] selftests/x86/fsgsbase: Test ptracer-induced GS base write with FSGSBASE Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 15/17] x86/fsgsbase/64: Enable FSGSBASE on 64bit by default and add a chicken bit Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 16/17] x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 17/17] Documentation/x86/64: Add documentation for GS/FS addressing mode Chang S. Bae
2019-10-04 22:54   ` Randy Dunlap
2019-11-15 18:29 ` [PATCH v9 00/17] Enable FSGSBASE instructions Thomas Gleixner
2019-11-15 19:12   ` Andi Kleen
2019-11-29 14:56     ` Metzger, Markus T
2019-11-29 16:51       ` Andy Lutomirski
2019-12-02  8:23         ` Metzger, Markus T
2019-12-04 20:20           ` Andy Lutomirski
2019-12-10  8:27             ` Metzger, Markus T
2020-02-24 18:02             ` Bae, Chang Seok
2020-04-13 20:03               ` Sasha Levin
2020-04-14  0:32                 ` Andi Kleen
2020-04-17 13:30                   ` Sasha Levin
2020-04-17 15:52                     ` Andy Lutomirski
2020-04-20 14:13                       ` Andi Kleen
2020-04-20 17:14                         ` Thomas Gleixner
2020-04-21 16:06                           ` Sasha Levin
2020-04-21 16:49                             ` Andy Lutomirski
2020-04-21 20:02                               ` Andi Kleen
2020-04-21 17:15                             ` Bae, Chang Seok
2020-04-21 19:56                             ` Andi Kleen
2020-04-21 20:21                               ` Andy Lutomirski
2020-04-21 20:51                                 ` Sasha Levin
2020-04-22 23:00                                   ` Andy Lutomirski
2020-04-23  4:08                                     ` Sasha Levin
2020-04-25 22:39                                       ` Thomas Gleixner
2020-04-26  2:52                                         ` Sasha Levin [this message]
2020-04-26 10:04                                           ` Thomas Gleixner
2020-04-14 15:47                 ` Bae, Chang Seok

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