linux-kernel - Re: [PATCH] x86_32: Initialize the cr4 shadow on cpu init

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Message-ID: <20150227151901.5ddd3c74@gandalf.local.home>
Date:	Fri, 27 Feb 2015 15:19:01 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Peter Zijlstra (Intel)" <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH] x86_32: Initialize the cr4 shadow on cpu init

On Fri, 27 Feb 2015 11:53:39 -0800
Andy Lutomirski <luto@...capital.net> wrote:

> This is embarrassing.  I must have gotten lucky testing it.
> 

The thing is, it booted fine on all my tests. It wasn't until I did
hotplug where it crashed.

I'm not sure what's in CR4 when the CPU comes up, but perhaps zero is
fine to start out and the writes to CR4 update makes the shadow and reg
the same. It's when we hotplug that the two become out of sync.

Just my theory.

-- Steve
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