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=-12.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 861DDC4332E for ; Tue, 2 Mar 2021 15:47:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DE4060295 for ; Tue, 2 Mar 2021 15:47:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1575797AbhCBPoT (ORCPT ); Tue, 2 Mar 2021 10:44:19 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:51708 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350913AbhCBM7E (ORCPT ); Tue, 2 Mar 2021 07:59:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614689795; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=M9fL7n3Tv5twMpsBGgac3V/MmjGJOrbN2fKp4Wp/lhk=; b=R5gAe6uues6+PEcUr3UwZPxiyBWtbbTyHbwIQVhrIejSLcFpnA/YKwvKXV01/7VdVfSz9u +5400peLiY+Pje+RdA4qkO5mkjelEsPlxsTyPX9Q9RllTnoP5FAbA3JfVAl2mwBcpcjVZX i3m4NGWd+6PaRkHHo3rHpu9a20R+dbk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-561-oaeMdRUFPTC5FrLTLYTNBQ-1; Tue, 02 Mar 2021 07:56:33 -0500 X-MC-Unique: oaeMdRUFPTC5FrLTLYTNBQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6DD501E570; Tue, 2 Mar 2021 12:56:32 +0000 (UTC) Received: from localhost.localdomain (ovpn-114-4.rdu2.redhat.com [10.10.114.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D3EC060BFA; Tue, 2 Mar 2021 12:56:31 +0000 (UTC) Subject: Re: [PATCH] KVM: nSVM: Optimize L12 to L2 vmcb.save copies To: Sean Christopherson Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com, vkuznets@redhat.com, wei.huang2@amd.com References: <20210301200844.2000-1-cavery@redhat.com> From: Cathy Avery Message-ID: <9c7e4dec-2181-1720-5981-3ae25c5bb0d9@redhat.com> Date: Tue, 2 Mar 2021 07:56:31 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/1/21 7:59 PM, Sean Christopherson wrote: > 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? I was going to tackle CR in a follow up patch. I should have mentioned that but it makes sense to go ahead and do it now. > >> - 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. I 'll take a look at CR2 as well. Thanks for the feedback, Cathy > >> + >> 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 >>