From: Borislav Petkov <bp@alien8.de>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Fenghua Yu <fenghua.yu@intel.com>, Ingo Molnar <mingo@redhat.com>,
H Peter Anvin <hpa@zytor.com>, Ashok Raj <ashok.raj@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Michael Chan <michael.chan@broadcom.com>,
Ravi V Shankar <ravi.v.shankar@intel.com>,
Ricardo Neri <ricardo.neri@intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>
Subject: Re: [PATCH v3 08/10] x86/setcpuid: Add kernel option setcpuid
Date: Tue, 5 Feb 2019 07:18:01 +0100 [thread overview]
Message-ID: <20190205061801.GC21801@zn.tnic> (raw)
In-Reply-To: <722af610-da30-2318-9ddd-d991238ce334@intel.com>
On Mon, Feb 04, 2019 at 03:24:23PM -0800, Dave Hansen wrote:
> Actually, there's one part of all this that I forgot. Will split lock
> detection be enumerated _widely_?
You never know what users will do. The moment it gets out, it better be
designed properly, along with the chicken bits.
> IOW, will my laptop in 5 years enumerate support for it?
Don't tell me this is going to be another MPX fiasco :-\
Or is this something along the lines of "let's see whether it takes off
and if yes, we'll commit to it or otherwise remove it and not even waste
a CPUID leaf"?
> If so, we surely don't want to enable this everyhwhere: it will break
> old apps. Doesn't that mean that we need both feature detection and
> another separate bit for folks to opt-in?
Well, if it breaks old apps, it probably needs to be opt-in anyway.
And for that you don't need setcpuid either - you simply boot with
"split_lock_ac" or whatever and the kernel pokes that MSR_TEST_CTL or
whatever else it needs to detect in hw for split lock and sets the
X86_FEATURE bits if detection is successful.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2019-02-05 6:18 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-02 5:14 [PATCH v3 00/10] x86/split_lock: Enable #AC exception for split locked accesses Fenghua Yu
2019-02-02 5:14 ` [PATCH v3 01/10] x86/common: Align cpu_caps_cleared and cpu_caps_set to unsigned long Fenghua Yu
2019-02-02 5:14 ` [PATCH v3 02/10] drivers/net/b44: Align pwol_mask to unsigned long for better performance Fenghua Yu
2019-02-02 5:14 ` [PATCH v3 03/10] wlcore: Align reg_ch_conf_pending and tmp_ch_bitmap " Fenghua Yu
2019-02-02 5:14 ` [PATCH v3 04/10] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access Fenghua Yu
2019-02-02 5:14 ` [PATCH v3 05/10] x86/clearcpuid: Support multiple clearcpuid options Fenghua Yu
2019-02-02 5:14 ` [PATCH v3 06/10] x86/clearcpuid: Support feature flag string in kernel option clearcpuid Fenghua Yu
2019-02-02 5:14 ` [PATCH v3 07/10] Change document for " Fenghua Yu
2019-02-02 5:14 ` [PATCH v3 08/10] x86/setcpuid: Add kernel option setcpuid Fenghua Yu
2019-02-04 17:49 ` Thomas Gleixner
2019-02-04 19:05 ` Dave Hansen
2019-02-04 19:57 ` Borislav Petkov
2019-02-04 20:46 ` Dave Hansen
2019-02-04 21:40 ` Borislav Petkov
2019-02-04 22:14 ` Fenghua Yu
2019-02-05 6:10 ` Borislav Petkov
2019-02-04 23:24 ` Dave Hansen
2019-02-05 6:18 ` Borislav Petkov [this message]
2019-02-05 16:46 ` Dave Hansen
2019-02-05 17:09 ` Peter Zijlstra
2019-02-05 8:57 ` Peter Zijlstra
2019-02-05 13:15 ` Peter Zijlstra
2019-02-05 8:48 ` Peter Zijlstra
2019-02-05 15:19 ` Dave Hansen
2019-02-05 15:43 ` Borislav Petkov
2019-02-05 18:26 ` Fenghua Yu
2019-02-05 17:04 ` Peter Zijlstra
2019-02-10 19:20 ` Thomas Gleixner
2019-02-11 19:16 ` Fenghua Yu
2019-02-12 13:37 ` Peter Zijlstra
2019-02-12 13:51 ` Thomas Gleixner
2019-02-12 16:48 ` Peter Zijlstra
2019-02-12 16:50 ` Dave Hansen
2019-02-12 17:52 ` Yu, Fenghua
2019-02-04 21:09 ` Fenghua Yu
2019-02-05 8:51 ` Peter Zijlstra
2019-02-05 15:21 ` Dave Hansen
2019-02-05 15:34 ` Peter Zijlstra
2019-02-02 5:14 ` [PATCH v3 09/10] x86/split_lock: Define #AC for split lock feature Fenghua Yu
2019-02-04 18:41 ` Dave Hansen
2019-02-04 18:45 ` Fenghua Yu
2019-02-04 19:00 ` Dave Hansen
2019-02-04 19:03 ` Fenghua Yu
2019-02-02 5:14 ` [PATCH v3 10/10] x86/split_lock: Handle #AC exception for split lock Fenghua Yu
2019-02-04 11:00 ` kbuild test robot
2019-02-04 14:43 ` kbuild test robot
2019-02-11 10:53 ` Ingo Molnar
2019-02-11 18:10 ` Fenghua Yu
2019-02-13 8:14 ` Ingo Molnar
2019-02-13 14:37 ` Yu, Fenghua
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