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 13:24:28 +0200
Message-ID: <20101109112428.GQ9036@redhat.com>
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Cc: Avi Kivity <avi@redhat.com>, kvm@vger.kernel.org
To: lidong chen <chen.lidong.kernel@gmail.com>
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On Tue, Nov 09, 2010 at 06:24:06PM +0800, lidong chen wrote:
> the version of guest os is 2.6.16.60-0.21-bigsmp.
>=20
> the virtio driver we use from RHEL5.5.
>=20
This guest does not support MSI.

> 2010/11/9 Gleb Natapov <gleb@redhat.com>:
> > On Tue, Nov 09, 2010 at 05:04:15PM +0800, lidong chen wrote:
> >> how to configure virtio to use MSI? I didn't found out it.
> >> thanks.
> >>
> > It looks like it should be enabled by default. What is you guest?
> >
> >> 2010/11/9 Gleb Natapov <gleb@redhat.com>:
> >> > 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 t=
han
> >> >> 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 no=
rmal?
> >> >> I add the printk in function tdp_page_fault below.
> >> >> =9A =9A =9A =9A pfn =3D gfn_to_pfn(vcpu->kvm, gfn);
> >> >> =9A =9A =9A =9A if (is_error_pfn(pfn)) {
> >> >> =9A =9A =9A =9A =9A =9A =9A =9A kvm_release_pfn_clean(pfn);
> >> >> =9A =9A =9A =9A =9A =9A =9A =9A if( printk_ratelimit() ) {
> >> >> =9A =9A =9A =9A =9A =9A =9A =9A =9A =9A =9A =9A printk(KERN_EME=
RG "error gpa is %ld\n", gpa);
> >> >> =9A =9A =9A =9A =9A =9A =9A =9A }
> >> >> =9A =9A =9A =9A =9A =9A =9A =9A return is_fault_pfn(pfn) ? -EFA=
ULT : 1;
> >> >> =9A =9A =9A =9A }
> >> >>
> >> >> 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.
> >> >
> >> > --
> >> > =9A =9A =9A =9A =9A =9A =9A =9A =9A =9A =9A =9AGleb.
> >> >
> >
> > --
> > =9A =9A =9A =9A =9A =9A =9A =9A =9A =9A =9A =9AGleb.
> >

--
			Gleb.