From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA52DC4360C for ; Thu, 26 Sep 2019 21:43:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA249222C2 for ; Thu, 26 Sep 2019 21:43:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726322AbfIZVnF (ORCPT ); Thu, 26 Sep 2019 17:43:05 -0400 Received: from mga07.intel.com ([134.134.136.100]:8270 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725955AbfIZVnE (ORCPT ); Thu, 26 Sep 2019 17:43:04 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Sep 2019 14:43:03 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,553,1559545200"; d="scan'208";a="192958531" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.41]) by orsmga003.jf.intel.com with ESMTP; 26 Sep 2019 14:43:03 -0700 From: Sean Christopherson To: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Reto Buerki Subject: [PATCH 2/2] KVM: VMX: Skip GUEST_CR3 VMREAD+VMWRITE if the VMCS is up-to-date Date: Thu, 26 Sep 2019 14:43:02 -0700 Message-Id: <20190926214302.21990-3-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190926214302.21990-1-sean.j.christopherson@intel.com> References: <20190926214302.21990-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Skip the VMWRITE to update GUEST_CR3 if CR3 is not available, i.e. has not been read from the VMCS since the last VM-Enter. If vcpu->arch.cr3 is stale, kvm_read_cr3(vcpu) will refresh vcpu->arch.cr3 from the VMCS, meaning KVM will do a VMREAD and then VMWRITE the value it just pulled from the VMCS. Note, this is a purely theoretical change, no instances of skipping the VMREAD+VMWRITE have been observed with this change. Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/vmx.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index b530950a9c2b..6de09f60edf3 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -3003,10 +3003,12 @@ void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) if (is_guest_mode(vcpu)) skip_cr3 = true; - else if (enable_unrestricted_guest || is_paging(vcpu)) - guest_cr3 = kvm_read_cr3(vcpu); - else + else if (!enable_unrestricted_guest && !is_paging(vcpu)) guest_cr3 = to_kvm_vmx(kvm)->ept_identity_map_addr; + else if (test_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail)) + guest_cr3 = vcpu->arch.cr3; + else + skip_cr3 = true; /* vmcs01.GUEST_CR3 is up-to-date. */ ept_load_pdptrs(vcpu); } -- 2.22.0