From: "Jan Beulich" <jbeulich@novell.com>
To: "Joerg Roedel" <joro@8bytes.org>
Cc: <mingo@elte.hu>, "Andi Kleen" <andi@firstfloor.org>,
<tglx@linutronix.de>, <linux-kernel@vger.kernel.org>,
<hpa@zytor.com>
Subject: Re: [PATCH] i386: improve double fault handling
Date: Thu, 24 Jul 2008 08:08:15 +0100 [thread overview]
Message-ID: <4888467F.76E4.0078.0@novell.com> (raw)
In-Reply-To: <20080723214320.GC13662@8bytes.org>
>>> Joerg Roedel <joro@8bytes.org> 23.07.08 23:43 >>>
>On Fri, Jul 18, 2008 at 01:30:42PM +0100, Jan Beulich wrote:
>> Make the double fault handler use CPU-specific stacks. Add some
>> abstraction to simplify future change of other exception handlers to go
>> through task gates.
>
>What is the benefit of exception handlers going through task gates?
>Hardware task switches are not very well supported in virtualization
>(e.g. its has issues in KVM and is also not in Xen for a long time).
The main goal is to get to a different stack. While at present this is done
only for the double fault, I think generally NMI and MCE should also do
so, as they may be caused by a stack access (see x86-64, which runs
them on IST stacks), and hence continuing to run on that same stack
may not allow the exception to be handled.
Jan
next prev parent reply other threads:[~2008-07-24 7:07 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-18 12:30 [PATCH] i386: improve double fault handling Jan Beulich
2008-07-18 23:24 ` H. Peter Anvin
2008-07-21 8:54 ` Jan Beulich
2008-07-21 11:05 ` Ingo Molnar
2008-07-22 10:13 ` Jan Beulich
2008-07-28 13:42 ` Ingo Molnar
2008-07-28 13:45 ` H. Peter Anvin
2008-07-28 13:59 ` Jan Beulich
2008-07-28 14:02 ` H. Peter Anvin
2008-07-28 16:28 ` Ingo Molnar
2008-07-28 22:00 ` Chuck Ebbert
2008-07-31 10:46 ` Ingo Molnar
2008-07-23 21:43 ` Joerg Roedel
2008-07-24 7:08 ` Jan Beulich [this message]
2008-07-24 13:24 ` H. Peter Anvin
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