From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: Why so many vm exits caused by ept violation
Date: Tue, 9 Nov 2010 09:45:50 +0200
Message-ID: <20101109074550.GH9036@redhat.com>
References: <AANLkTin9MtnVsZJ2Zi7QmBB0_Z=rH8d0C-XdNuqzNsC4@mail.gmail.com>
 <4CD802AA.3040302@redhat.com>
 <AANLkTinO7ZMMoYKt-8eMHf9sWHO5FM4L60P46sKNVs1Y@mail.gmail.com>
 <AANLkTim1Yb6Gd8j1rwyKMO1RcWHaX7TK6Hhf7Wt5cast@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Avi Kivity <avi@redhat.com>, kvm@vger.kernel.org
To: lidong chen <chen.lidong.kernel@gmail.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mx1.redhat.com ([209.132.183.28]:42888 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752518Ab0KIHpw (ORCPT <rfc822;kvm@vger.kernel.org>);
	Tue, 9 Nov 2010 02:45:52 -0500
Content-Disposition: inline
In-Reply-To: <AANLkTim1Yb6Gd8j1rwyKMO1RcWHaX7TK6Hhf7Wt5cast@mail.gmail.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On Tue, Nov 09, 2010 at 03:37:44PM +0800, lidong chen wrote:
> sorry,i take mistake,
> 
> the ept violation is not caused by 2M hugepages, but caused by e1000
> emulated by qemu.
> I test uesd 2M hugepages and virio, the performance is better than
> e1000. but is still worse than xen. I will continue to find out other
> reason.
> 
> 
> 
> so, there are two question:
> 1.why have so many ept violation when used e1000?
> 
> 
> 2.when used virtio, there ara also such error happen.is this normal?
> I add the printk in function tdp_page_fault below.
>         pfn = gfn_to_pfn(vcpu->kvm, gfn);
>         if (is_error_pfn(pfn)) {
>                 kvm_release_pfn_clean(pfn);
>                 if( printk_ratelimit() ) {
>                         printk(KERN_EMERG "error gpa is %ld\n", gpa);
>                 }
>                 return is_fault_pfn(pfn) ? -EFAULT : 1;
>         }
> 
> and result is:
> [root@rhel6-kvm1 ~]# dmesg -c
> __ratelimit: 387 callbacks suppressed
> error gpa is 4273995776
> error gpa is 4273995776
> error gpa is 4273995776
> error gpa is 4273995776
> error gpa is 4273995776
> 
You should really print this in hex :) This is 0xfec00000 AKA
IOAPIC. Try to configure virtio to use MSI.

--
			Gleb.