From: Peter Zijlstra <peterz@infradead.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Greg KH <gregkh@linuxfoundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Andi Kleen <ak@linux.intel.com>,
Arjan Van De Ven <arjan.van.de.ven@intel.com>,
David Woodhouse <dwmw@amazon.co.uk>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/8] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature
Date: Mon, 8 Jan 2018 13:47:07 +0100 [thread overview]
Message-ID: <20180108124707.GH32035@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <d7413d40-7581-a994-5185-9f11c014cb0f@intel.com>
On Fri, Jan 05, 2018 at 07:12:12PM -0800, Dave Hansen wrote:
> On 01/05/2018 06:12 PM, Tim Chen wrote:
> > .macro ENABLE_IBRS
> > - ALTERNATIVE "jmp .Lskip_\@", "", X86_FEATURE_SPEC_CTRL
> > + testl $1, dynamic_ibrs
> > + jz .Lskip_\@
>
> There was an earlier suggestion to use STATIC_JUMP_IF_... here. That's
Yes, and thanks for Cc'ing me... :/
> a good suggestion, but we encountered some issues with it either
> crashing the kernel at boot or not properly turning on/off.
>
> We would love to do that minor really soon, but we figured everyone
> would rather see this version than wait for us to debug such a minor tweak.
Its not minor, you need that LFENCE without it. Which makes the whole
thing unconditionally expensive, which sucks.
next prev parent reply other threads:[~2018-01-08 12:47 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-06 2:12 [PATCH v2 0/8] IBRS patch series Tim Chen
2018-01-06 2:12 ` [PATCH v2 1/8] x86/feature: Detect the x86 IBRS feature to control Speculation Tim Chen
2018-01-06 12:56 ` Borislav Petkov
2018-01-07 17:14 ` Tim Chen
2018-01-07 18:31 ` Borislav Petkov
2018-01-09 18:13 ` Dave Hansen
2018-01-09 18:55 ` Borislav Petkov
2018-01-08 16:14 ` Paolo Bonzini
2018-01-09 10:39 ` Paolo Bonzini
2018-01-09 17:53 ` Tim Chen
2018-01-09 17:58 ` Paolo Bonzini
2018-01-09 22:59 ` Tim Chen
2018-01-18 23:28 ` Andy Lutomirski
2018-01-06 2:12 ` [PATCH v2 2/8] x86/enter: MACROS to set/clear IBRS Tim Chen
2018-01-07 12:03 ` Borislav Petkov
2018-01-07 17:12 ` Tim Chen
2018-01-07 18:44 ` Borislav Petkov
2018-01-08 22:24 ` Tim Chen
2018-01-06 2:12 ` [PATCH v2 3/8] x86/enter: Use IBRS on syscall and interrupts Tim Chen
2018-01-07 19:27 ` Borislav Petkov
2018-01-06 2:12 ` [PATCH v2 4/8] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature Tim Chen
2018-01-06 3:12 ` Dave Hansen
2018-01-08 12:47 ` Peter Zijlstra [this message]
2018-01-08 16:14 ` Peter Zijlstra
2018-01-08 17:28 ` Tim Chen
2018-01-08 17:42 ` Peter Zijlstra
2018-01-08 19:34 ` Woodhouse, David
2018-01-08 19:52 ` Lu, Hongjiu
2018-01-09 10:40 ` Thomas Gleixner
2018-01-09 17:55 ` Tim Chen
2018-01-09 18:13 ` David Woodhouse
2018-01-09 20:31 ` Tim Chen
2018-01-27 13:59 ` Konrad Rzeszutek Wilk
2018-01-27 14:26 ` David Woodhouse
2018-01-06 8:54 ` Greg KH
2018-01-06 18:10 ` Tim Chen
2018-01-06 21:25 ` Konrad Rzeszutek Wilk
2018-01-07 8:20 ` Greg KH
2018-01-06 14:41 ` Konrad Rzeszutek Wilk
2018-01-06 17:33 ` Dave Hansen
2018-01-06 17:41 ` Van De Ven, Arjan
2018-01-06 19:22 ` Dave Hansen
2018-01-06 19:47 ` Thomas Gleixner
2018-01-06 21:32 ` Konrad Rzeszutek Wilk
2018-01-06 21:34 ` Van De Ven, Arjan
2018-01-06 21:41 ` Konrad Rzeszutek Wilk
2018-01-06 21:44 ` Van De Ven, Arjan
2018-01-06 21:39 ` Thomas Gleixner
2018-01-06 21:46 ` Is: Linus, name for 'spectre' variable. Was:Re: " Konrad Rzeszutek Wilk
2018-01-06 18:23 ` Tim Chen
2018-01-06 18:20 ` Tim Chen
2018-01-08 15:08 ` Peter Zijlstra
2018-01-08 15:29 ` Van De Ven, Arjan
2018-01-08 17:02 ` Tim Chen
2018-01-08 15:11 ` Peter Zijlstra
2018-01-08 15:15 ` Peter Zijlstra
2018-01-08 15:53 ` Peter Zijlstra
2018-01-09 0:29 ` Borislav Petkov
2018-01-09 18:05 ` Tim Chen
2018-01-06 2:12 ` [PATCH v2 5/8] x86/idle: Disable IBRS entering idle and enable it on wakeup Tim Chen
2018-01-06 2:12 ` [PATCH v2 6/8] x86/microcode: Recheck IBRS features on microcode reload Tim Chen
2018-01-06 12:09 ` Woodhouse, David
2018-01-09 0:34 ` Borislav Petkov
2018-01-06 2:12 ` [PATCH v2 7/8] x86: Do not use dynamic IBRS if retpoline is enabled Tim Chen
2018-01-06 2:12 ` [PATCH v2 8/8] x86: Use IBRS for firmware update path Tim Chen
2018-01-06 8:55 ` Greg KH
2018-01-06 8:57 ` Greg KH
2018-01-06 6:43 ` [PATCH v2 0/8] IBRS patch series Tim Chen
2018-01-06 12:00 ` Woodhouse, David
2018-01-06 12:11 ` Woodhouse, David
-- strict thread matches above, loose matches on Subject: below --
2018-01-08 17:43 [PATCH v2 4/8] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature Alexey Dobriyan
2018-01-08 18:30 ` Andrea Arcangeli
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