From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id EB0B56B00A7 for ; Mon, 18 Jan 2010 20:58:20 -0500 (EST) Message-ID: <4B5510B1.9010202@zytor.com> Date: Mon, 18 Jan 2010 17:53:53 -0800 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [PATCH v3 04/12] Add "handle page fault" PV helper. References: <1262700774-1808-1-git-send-email-gleb@redhat.com> <1262700774-1808-5-git-send-email-gleb@redhat.com> <1263490267.4244.340.camel@laptop> <20100117144411.GI31692@redhat.com> <4B541D08.9040802@zytor.com> <20100118085022.GA30698@redhat.com> In-Reply-To: <20100118085022.GA30698@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Gleb Natapov Cc: Peter Zijlstra , kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, avi@redhat.com, mingo@elte.hu, tglx@linutronix.de, riel@redhat.com, cl@linux-foundation.org List-ID: On 01/18/2010 12:50 AM, Gleb Natapov wrote: > On Mon, Jan 18, 2010 at 12:34:16AM -0800, H. Peter Anvin wrote: >> On 01/17/2010 06:44 AM, Gleb Natapov wrote: >>> On Thu, Jan 14, 2010 at 06:31:07PM +0100, Peter Zijlstra wrote: >>>> On Tue, 2010-01-05 at 16:12 +0200, Gleb Natapov wrote: >>>>> Allow paravirtualized guest to do special handling for some page faults. >>>>> >>>>> The patch adds one 'if' to do_page_fault() function. The call is patched >>>>> out when running on physical HW. I ran kernbech on the kernel with and >>>>> without that additional 'if' and result were rawly the same: >>>> >>>> So why not program a different handler address for the #PF/#GP faults >>>> and avoid the if all together? >>> I would gladly use fault vector reserved by x86 architecture, but I am >>> not sure Intel will be happy about it. >>> >> >> That's what it's there for... see Peter Z.'s response. >> > Do you mean I can use one of exception vectors reserved by Intel > (20-31)? What Peter Z says is that I can register my own handler for > #PF and avoid the 'if' in non PV case as far as I understand him. > What I mean is that vector 14 is page faults -- that's what it is all about. Why on Earth do you need another vector? -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org