From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 752AE6B0089 for ; Fri, 8 Oct 2010 12:11:15 -0400 (EDT) Date: Fri, 8 Oct 2010 13:07:49 -0300 From: Marcelo Tosatti Subject: Re: [PATCH v6 03/12] Retry fault before vmentry Message-ID: <20101008160749.GA31315@amt.cnet> References: <1286207794-16120-1-git-send-email-gleb@redhat.com> <1286207794-16120-4-git-send-email-gleb@redhat.com> <20101005155409.GB28955@amt.cnet> <20101006110704.GW11145@redhat.com> <20101006142050.GA31423@amt.cnet> <20101007184457.GA8354@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101007184457.GA8354@redhat.com> Sender: owner-linux-mm@kvack.org To: Gleb Natapov Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, avi@redhat.com, mingo@elte.hu, a.p.zijlstra@chello.nl, tglx@linutronix.de, hpa@zytor.com, riel@redhat.com, cl@linux-foundation.org List-ID: On Thu, Oct 07, 2010 at 08:44:57PM +0200, Gleb Natapov wrote: > On Wed, Oct 06, 2010 at 11:20:50AM -0300, Marcelo Tosatti wrote: > > On Wed, Oct 06, 2010 at 01:07:04PM +0200, Gleb Natapov wrote: > > > > Can't you set a bit in vcpu->requests instead, and handle it in "out:" > > > > at the end of vcpu_enter_guest? > > > > > > > > To have a single entry point for pagefaults, after vmexit handling. > > > Jumping to "out:" will skip vmexit handling anyway, so we will not reuse > > > same call site anyway. I don't see yet why the way you propose will have > > > an advantage. > > > > What i meant was to call pagefault handler after vmexit handling. > > > > Because the way it is in your patch now, with pre pagefault on entry, > > one has to make an effort to verify ordering wrt other events on entry > > processing. > > > What events do you have in mind? TLB flushing, event injection, etc. > > With pre pagefault after vmexit, its more natural. > > > I do not see non-ugly way to pass information that is needed to perform > the prefault to the place you want me to put it. We can skip guest entry > in case prefault was done which will have the same effect as your > proposal, but I want to have a good reason to do so since otherwise we > will just do more work for nothing on guest entry. The reason is that it becomes similar to normal pagefault handling. I don't have a specific bug to give you as example. > > > Does that make sense? > > -- > Gleb. -- 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