From: "H. Peter Anvin" <hpa@zytor.com>
To: Kees Cook <kees.cook@canonical.com>
Cc: linux-kernel@vger.kernel.org, Len Brown <len.brown@intel.com>,
Pavel Machek <pavel@ucw.cz>, "Rafael J. Wysocki" <rjw@sisk.pl>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Pekka Enberg <penberg@cs.helsinki.fi>,
Brian Gerst <brgerst@gmail.com>,
Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH] x86: add missing verify_cpu to 32bit wakeup
Date: Fri, 01 Jul 2011 14:26:27 -0700 [thread overview]
Message-ID: <4E0E3B83.3000403@zytor.com> (raw)
In-Reply-To: <20110701211943.GA7042@outflux.net>
On 07/01/2011 02:19 PM, Kees Cook wrote:
> Some BIOSes will reset the Intel XD_DISABLE MSR bit when resuming from S3,
> which can interact poorly with ebba638ae723d8a8fc2f7abce5ec18b688b791d7.
> In 32bit PAE mode, this can lead to a fault when EFER is restored by
> the kernel wakeup routines, due to it setting the NX bit for a CPU
> that (thanks to the BIOS reset) now incorrectly thinks it lacks the NX
> feature. 64bit wakeup already handled this through its common call path
> that would hit verify_cpu(). 32bit has a separate path for restoring
> CPU state on S3 wakeup, and needed to call verify_cpu() to handle this
> situation.
For S3, we should save/restore MISC_ENABLE instead... in fact, we
already save it, we just restore it too late.
-hpa
next prev parent reply other threads:[~2011-07-01 21:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-01 21:19 [PATCH] x86: add missing verify_cpu to 32bit wakeup Kees Cook
2011-07-01 21:26 ` H. Peter Anvin [this message]
2011-07-01 22:36 ` Kees Cook
2011-07-01 23:07 ` H. Peter Anvin
2011-07-03 12:15 ` Pavel Machek
2011-07-03 19:15 ` Kees Cook
2011-07-03 21:25 ` H. Peter Anvin
2011-07-03 21:34 ` Pavel Machek
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