Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753314Ab0DLIe4 (ORCPT ); Mon, 12 Apr 2010 04:34:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55009 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752889Ab0DLIez (ORCPT ); Mon, 12 Apr 2010 04:34:55 -0400 Message-ID: <4BC2DB27.7060005@redhat.com> Date: Mon, 12 Apr 2010 11:34:47 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Thunderbird/3.0.4 MIME-Version: 1.0 To: Xiao Guangrong CC: Marcelo Tosatti , KVM list , LKML Subject: Re: [PATCH 4/6] KVM MMU: optimize for writing cr4 References: <4BC2D2E2.1030604@cn.fujitsu.com> <4BC2D3E0.8070602@cn.fujitsu.com> In-Reply-To: <4BC2D3E0.8070602@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1482 Lines: 49 On 04/12/2010 11:03 AM, Xiao Guangrong wrote: > Usually, OS changes CR4.PGE bit to flush all global page, under this > case, no need reset mmu and just flush tlb > > Signed-off-by: Xiao Guangrong > --- > arch/x86/kvm/x86.c | 9 +++++++++ > 1 files changed, 9 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index fd5c3d3..2aaa6fb 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -463,6 +463,15 @@ void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) > unsigned long old_cr4 = kvm_read_cr4(vcpu); > unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE; > > + if (cr4 == old_cr4) > + return; > + > + if ((cr4 ^ old_cr4) == X86_CR4_PGE) { > + kvm_mmu_sync_roots(vcpu); > + kvm_mmu_flush_tlb(vcpu); > + return; > + } > + > if (cr4& CR4_RESERVED_BITS) { > kvm_inject_gp(vcpu, 0); > return; > Later we have: > kvm_x86_ops->set_cr4(vcpu, cr4); > vcpu->arch.cr4 = cr4; > vcpu->arch.mmu.base_role.cr4_pge = (cr4 & X86_CR4_PGE) && > !tdp_enabled; All of which depend on cr4. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/