From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: with kerenl 2.6.27, CONFIG_KVM_GUEST does not work Date: Sat, 11 Oct 2008 15:04:36 -0300 Message-ID: <20081011180436.GA13387@dmt.cnet> References: <519a8b110810100911j2e8229a2mf86f770b724a1bc3@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org To: xming , Avi Kivity Return-path: Received: from mx2.redhat.com ([66.187.237.31]:52206 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932591AbYJKSFv (ORCPT ); Sat, 11 Oct 2008 14:05:51 -0400 Content-Disposition: inline In-Reply-To: <519a8b110810100911j2e8229a2mf86f770b724a1bc3@mail.gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: On Fri, Oct 10, 2008 at 06:11:08PM +0200, xming wrote: > Kernel 2.6.27 + kvm-76 on the host really gives some performance boost here. > but: > > When running 2.6.27 compiled with CONFIG_KVM_GUEST=y in the guest, the guest > won't start, lot's of segfaults (in the guest) especially udev initializations. > > unset CONFIG_KVM_GUEST=y, then the guest runs fine Does the attached work for you? Avi, do you have thoughts on how to proceed with pvmmu? Using hypercalls instead of faults can still be beneficial (for the first write before page goes out of sync, or for non-leaf tables which currently don't go oos). But at the current state pvmmu should be slower in most loads. Perhaps disable it? KVM: MMU: sync root on paravirt TLB flush The pvmmu TLB flush handler should request a root sync, similarly to a native read-write CR3. Signed-off-by: Marcelo Tosatti diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 79cb4a9..7e70e97 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2747,6 +2747,7 @@ static int kvm_pv_mmu_write(struct kvm_vcpu *vcpu, static int kvm_pv_mmu_flush_tlb(struct kvm_vcpu *vcpu) { kvm_x86_ops->tlb_flush(vcpu); + set_bit(KVM_REQ_MMU_SYNC, &vcpu->requests); return 1; }