From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Hansen <dave.hansen@intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linuxfoundation.org>,
x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>,
David Woodhouse <dwmw@amazon.co.uk>,
Tim Chen <tim.c.chen@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Andi Kleen <ak@linux.intel.com>,
Greg KH <gregkh@linuxfoundation.org>,
Andy Lutomirski <luto@kernel.org>,
Arjan Van De Ven <arjan.van.de.ven@intel.com>,
Borislav Petkov <bp@suse.de>, "Raj, Ashok" <ashok.raj@intel.com>
Subject: Re: [patch RFC 1/5] x86/CPU: Sync CPU feature flags late
Date: Wed, 10 Jan 2018 02:44:02 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1801100242550.2200@nanos> (raw)
In-Reply-To: <f70ea6ad-d563-5f60-2657-0551249a70e6@intel.com>
On Tue, 9 Jan 2018, Dave Hansen wrote:
> On 01/09/2018 05:06 PM, Thomas Gleixner wrote:
> > This is for the case where we need to set feature flags late, like, for
> > example, after late microcode patch has been loaded which has enabled
> > new CPUID bits.
> >
> > This has no effect on alternatives patching.
>
> In other words, if you use late microcode loading for getting IBRS, you
> don't get ALTERNATIVE patching and its benefits?
>
> I'll also profess some microcode ignorance here. Is "late microcode
> patching" *all* of the stuff we do from the OS, or do we have early and
> late Linux loading in addition to what the BIOS can do?
IBRS wont use alternatives for that and various other reasons. It has to be
static key based so we can patch it late
Thanks,
tglx
next prev parent reply other threads:[~2018-01-10 1:44 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-10 1:06 [patch RFC 0/5] x86/spectre_v2: Initial integration of IBRS into the spectre_v2 mechanics Thomas Gleixner
2018-01-10 1:06 ` [patch RFC 1/5] x86/CPU: Sync CPU feature flags late Thomas Gleixner
2018-01-10 1:37 ` Dave Hansen
2018-01-10 1:39 ` Van De Ven, Arjan
2018-01-10 1:47 ` Thomas Gleixner
2018-01-10 2:57 ` Andy Lutomirski
2018-01-10 11:02 ` Thomas Gleixner
2018-01-10 1:44 ` Thomas Gleixner [this message]
2018-01-10 6:20 ` Ingo Molnar
2018-01-10 11:33 ` Borislav Petkov
2018-01-10 12:38 ` Thomas Gleixner
2018-01-10 1:06 ` [patch RFC 2/5] x86/spectre: Simplify spectre code a bit Thomas Gleixner
2018-01-10 6:22 ` Ingo Molnar
2018-01-10 1:06 ` [patch RFC 3/5] x86/spectre: Prepare for IBRS selection Thomas Gleixner
2018-01-10 1:51 ` Dave Hansen
2018-01-10 1:06 ` [patch RFC 4/5] x86/cpufeatures: Detect Speculation control feature Thomas Gleixner
2018-01-10 6:32 ` Ingo Molnar
2018-01-10 11:06 ` Thomas Gleixner
2018-01-10 1:06 ` [patch RFC 5/5] x86/speculation: Add basic speculation control code Thomas Gleixner
2018-01-10 2:02 ` Dave Hansen
2018-01-10 4:11 ` Justin Forbes
2018-01-10 9:22 ` Peter Zijlstra
2018-01-10 9:27 ` David Woodhouse
2018-01-10 10:03 ` Peter Zijlstra
2018-01-10 11:22 ` David Woodhouse
2018-01-10 11:41 ` Thomas Gleixner
2018-01-10 11:45 ` Peter Zijlstra
2018-01-10 11:54 ` Andrea Arcangeli
2018-01-10 11:58 ` David Woodhouse
2018-01-10 12:01 ` Andrea Arcangeli
2018-01-10 12:07 ` Andrea Arcangeli
2018-01-10 12:12 ` David Woodhouse
2018-01-10 12:20 ` Andrea Arcangeli
2018-01-10 12:27 ` Andrea Arcangeli
2018-01-10 13:42 ` Van De Ven, Arjan
2018-01-10 12:09 ` David Woodhouse
2018-01-10 12:17 ` Andrea Arcangeli
2018-01-10 12:29 ` David Woodhouse
2018-01-10 12:41 ` Andrea Arcangeli
2018-01-10 12:47 ` Jiri Kosina
2018-01-10 12:51 ` David Woodhouse
2018-01-10 13:02 ` Andrea Arcangeli
2018-01-10 13:05 ` Andrea Arcangeli
2018-01-10 13:10 ` Andrea Arcangeli
2018-01-10 13:12 ` Andrea Arcangeli
2018-01-10 12:57 ` Andrea Arcangeli
2018-01-10 13:07 ` David Woodhouse
2018-01-10 13:45 ` Van De Ven, Arjan
2018-01-10 13:52 ` Andrea Arcangeli
2018-01-10 13:53 ` Van De Ven, Arjan
2018-01-10 21:35 ` Tim Chen
2018-01-10 22:13 ` Andrea Arcangeli
2018-01-10 13:46 ` Thomas Gleixner
2018-01-10 13:51 ` Van De Ven, Arjan
2018-01-10 13:53 ` Thomas Gleixner
2018-01-10 13:58 ` David Woodhouse
2018-01-10 14:10 ` Andrea Arcangeli
2018-01-10 14:14 ` Van De Ven, Arjan
2018-01-10 14:59 ` Dave Hansen
2018-01-10 15:13 ` Andrea Arcangeli
2018-01-10 15:24 ` David Woodhouse
2018-01-10 15:47 ` Andrea Arcangeli
2018-01-10 15:56 ` David Woodhouse
2018-01-10 13:10 ` Jiri Kosina
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