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=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 77D2DC433DB for ; Tue, 2 Mar 2021 15:56:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30AC364E7C for ; Tue, 2 Mar 2021 15:56:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1577740AbhCBPx7 (ORCPT ); Tue, 2 Mar 2021 10:53:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344316AbhCBBAb (ORCPT ); Mon, 1 Mar 2021 20:00:31 -0500 Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AEA16C061756 for ; Mon, 1 Mar 2021 16:59:50 -0800 (PST) Received: by mail-pj1-x1031.google.com with SMTP id c19so760928pjq.3 for ; Mon, 01 Mar 2021 16:59:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=0GR2I3eJe2UtIfAfosihtW3UQR7rmpxULTI4sriWpkE=; b=YWheDAR6u6jQ+x+YoZGmL6mYfI1Sw94IDVOxSguz9c47Jb+lwwWG7XuzCWymPqMgc4 wU9/uVt4DRkOdLZh3Z4B0BXd/NIecGPqsdqhBPYuVpaq6Hk3N8crCcRjMx1+Q1l7b/mq cwL4NFdo6ZWK4jq7JJZzFe1wdl3og4IumYeLlOJwXWAdE6h+ejJYOGrYLIjtPGiC2k5y RT+d5jTYJ9K4P6sjBtypb+d22oVF7tsBcgm/TaNADp5LdxnPmStOVsgCyg5MSh5rRarv Ybj/+7aJ5cujNzfoq023tyXUu6dESanahaj3cp89dLEd5hemfs9aUAUfsKQs5SiFHZzP d4gA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=0GR2I3eJe2UtIfAfosihtW3UQR7rmpxULTI4sriWpkE=; b=bwldfKm1P6dLIoet2U0+5n6N8uWfHD1TESM2CdAxNob8ZV4CD0d/wagMfcNf8ed/Ff LZLgTasm7LDZQ7bSDmx7dagpelROEJ7Y+0vtA8N+syyXRFWdnxvcgJbbyTFuVkFVGIlu Oc04NgEP92lObgdb+lseHU4vrKIQotWNg3e+iwpM4tOeiQkujPIZ2i8vlkBm51K/YIOV uWFRuV0MaiepghE9mgfvy00X8khAQFopGCP+goQEPuYtHnhck9xQV7p0dB12mmBehcgf 07Mici7mXxgeYZM7rFaLLaiix0ZVVR8abHLgBeLmuiYMW1tbqnQKcp6ryRJUkUuiSyyO d5lA== X-Gm-Message-State: AOAM530CkcfwivjPlmrTdi660p/likosdzT9tPZw18NkYvDNt+nMxHAA Wr7lq4mb0Dj9Tc5xtDhTi2N7Wg== X-Google-Smtp-Source: ABdhPJyQzP0940A7uVbKhp2s258qwAJB1kkcUlLzBHi9Sb2uTk5T4Tf5cZXaC9basCljEDUNSpleNg== X-Received: by 2002:a17:902:8342:b029:e1:1465:4bf0 with SMTP id z2-20020a1709028342b02900e114654bf0mr1319395pln.76.1614646790066; Mon, 01 Mar 2021 16:59:50 -0800 (PST) Received: from google.com ([2620:15c:f:10:5d06:6d3c:7b9:20c9]) by smtp.gmail.com with ESMTPSA id z16sm17076140pgj.51.2021.03.01.16.59.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Mar 2021 16:59:49 -0800 (PST) Date: Mon, 1 Mar 2021 16:59:43 -0800 From: Sean Christopherson To: Cathy Avery Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com, vkuznets@redhat.com, wei.huang2@amd.com Subject: Re: [PATCH] KVM: nSVM: Optimize L12 to L2 vmcb.save copies Message-ID: References: <20210301200844.2000-1-cavery@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210301200844.2000-1-cavery@redhat.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Mar 01, 2021, Cathy Avery wrote: > kvm_set_rflags(&svm->vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED); > svm_set_efer(&svm->vcpu, vmcb12->save.efer); > svm_set_cr0(&svm->vcpu, vmcb12->save.cr0); > svm_set_cr4(&svm->vcpu, vmcb12->save.cr4); Why not utilize VMCB_CR? > - svm->vcpu.arch.cr2 = vmcb12->save.cr2; > + svm->vmcb->save.cr2 = svm->vcpu.arch.cr2 = vmcb12->save.cr2; Same question for VMCB_CR2. Also, isn't writing svm->vmcb->save.cr2 unnecessary since svm_vcpu_run() unconditionally writes it? Alternatively, it shouldn't be too much work to add proper dirty tracking for CR2. VMX has to write the real CR2 every time because there's no VMCS field, but I assume can avoid the write and dirty update on the majority of VMRUNs. > + > kvm_rax_write(&svm->vcpu, vmcb12->save.rax); > kvm_rsp_write(&svm->vcpu, vmcb12->save.rsp); > kvm_rip_write(&svm->vcpu, vmcb12->save.rip); > > /* In case we don't even reach vcpu_run, the fields are not updated */ > - svm->vmcb->save.cr2 = svm->vcpu.arch.cr2; > svm->vmcb->save.rax = vmcb12->save.rax; > svm->vmcb->save.rsp = vmcb12->save.rsp; > svm->vmcb->save.rip = vmcb12->save.rip; > > - svm->vmcb->save.dr7 = vmcb12->save.dr7 | DR7_FIXED_1; > - svm->vcpu.arch.dr6 = vmcb12->save.dr6 | DR6_ACTIVE_LOW; > - vmcb_mark_dirty(svm->vmcb, VMCB_DR); > + /* These bits will be set properly on the first execution when new_vmc12 is true */ > + if (unlikely(new_vmcb12 || vmcb_is_dirty(vmcb12, VMCB_DR))) { > + svm->vmcb->save.dr7 = vmcb12->save.dr7 | DR7_FIXED_1; > + svm->vcpu.arch.dr6 = vmcb12->save.dr6 | DR6_ACTIVE_LOW; > + vmcb_mark_dirty(svm->vmcb, VMCB_DR); > + } > } > > static void nested_vmcb02_prepare_control(struct vcpu_svm *svm) > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 54610270f66a..9761a7ca8100 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -1232,6 +1232,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu) > svm->asid = 0; > > svm->nested.vmcb12_gpa = 0; > + svm->nested.last_vmcb12_gpa = 0; We should use INVALID_PAGE, '0' is a legal physical address and could theoretically get a false negative on the "new_vmcb12" check. > vcpu->arch.hflags = 0; > > if (!kvm_pause_in_guest(vcpu->kvm)) { > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > index fbbb26dd0f73..911868d4584c 100644 > --- a/arch/x86/kvm/svm/svm.h > +++ b/arch/x86/kvm/svm/svm.h > @@ -93,6 +93,7 @@ struct svm_nested_state { > u64 hsave_msr; > u64 vm_cr_msr; > u64 vmcb12_gpa; > + u64 last_vmcb12_gpa; > > /* These are the merged vectors */ > u32 *msrpm; > @@ -247,6 +248,11 @@ static inline void vmcb_mark_dirty(struct vmcb *vmcb, int bit) > vmcb->control.clean &= ~(1 << bit); > } > > +static inline bool vmcb_is_dirty(struct vmcb *vmcb, int bit) > +{ > + return !test_bit(bit, (unsigned long *)&vmcb->control.clean); > +} > + > static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu) > { > return container_of(vcpu, struct vcpu_svm, vcpu); > -- > 2.26.2 >