From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 03/15] KVM: x86: avoid unnecessarily guest page table walking Date: Thu, 09 Jun 2011 09:59:42 +0300 Message-ID: <4DF06F5E.9070608@redhat.com> References: <4DEE205E.8000601@cn.fujitsu.com> <4DEE20CA.90206@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , LKML , KVM To: Xiao Guangrong Return-path: Received: from mx1.redhat.com ([209.132.183.28]:5932 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752329Ab1FIG7u (ORCPT ); Thu, 9 Jun 2011 02:59:50 -0400 In-Reply-To: <4DEE20CA.90206@cn.fujitsu.com> Sender: kvm-owner@vger.kernel.org List-ID: On 06/07/2011 03:59 PM, Xiao Guangrong wrote: > We already get the guest physical address, so use it to read guest data > directly to avoid walking guest page table again > > Signed-off-by: Xiao Guangrong > --- > arch/x86/kvm/x86.c | 3 +-- > 1 files changed, 1 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 694538a..8be9ff6 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3930,8 +3930,7 @@ static int emulator_read_emulated(struct x86_emulate_ctxt *ctxt, > if ((gpa& PAGE_MASK) == APIC_DEFAULT_PHYS_BASE) > goto mmio; > > - if (kvm_read_guest_virt(ctxt, addr, val, bytes, exception) > - == X86EMUL_CONTINUE) > + if (!kvm_read_guest(vcpu->kvm, gpa, val, bytes)) > return X86EMUL_CONTINUE; This breaks is addr/bytes spans a page boundary. (the current code is also broken, but only for mmio; the new code is broken for ram as well). We need a gva_to_gpa() that returns a range of pages. -- error compiling committee.c: too many arguments to function