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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CA858C433EF for ; Wed, 23 Feb 2022 16:20:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242736AbiBWQVQ (ORCPT ); Wed, 23 Feb 2022 11:21:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242728AbiBWQVP (ORCPT ); Wed, 23 Feb 2022 11:21:15 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 9A8CCC55BC for ; Wed, 23 Feb 2022 08:20:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645633246; 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=TiO1yBPh8R5cpx6Ex6jDuaNR/N/orDWr7M4nBkkNmDQ=; b=J6AgSBXls+yLVWoCxJP9JwVk02y6ilbVbwHdap1LED4kzUCKJ4eB4+YDTLHPvz7ZzvA16x VyMHznbim5TwtbJDIXovCHbc0O0Rb0NYxNynU9QR45gR3E1PLfd+WC6RaAKGEBjG+uQrAy mnLSL0F3n8DlZYEQSOeQgGVjsIzxDGs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-442-KraB3RmFOe6YNaelxlfj1g-1; Wed, 23 Feb 2022 11:20:43 -0500 X-MC-Unique: KraB3RmFOe6YNaelxlfj1g-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 65E9AFC82; Wed, 23 Feb 2022 16:20:42 +0000 (UTC) Received: from starship (unknown [10.40.195.190]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0B2A29BEBD; Wed, 23 Feb 2022 16:20:40 +0000 (UTC) Message-ID: Subject: Re: [PATCH v2 10/18] KVM: x86/mmu: load new PGD after the shadow MMU is initialized From: Maxim Levitsky To: Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: seanjc@google.com Date: Wed, 23 Feb 2022 18:20:39 +0200 In-Reply-To: <20220217210340.312449-11-pbonzini@redhat.com> References: <20220217210340.312449-1-pbonzini@redhat.com> <20220217210340.312449-11-pbonzini@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2022-02-17 at 16:03 -0500, Paolo Bonzini wrote: > Now that __kvm_mmu_new_pgd does not look at the MMU's root_level and > shadow_root_level anymore, pull the PGD load after the initialization of > the shadow MMUs. Again, thanks a million for this! I once spend at least a hour figuring out why my kernel panics when I did a similiar change, only to figure out that __kvm_mmu_new_pgd needs to happen before mmu re-initialization. > > Besides being more intuitive, this enables future simplifications > and optimizations because it's not necessary anymore to compute the > role outside kvm_init_mmu. In particular, kvm_mmu_reset_context was not > attempting to use a cached PGD to avoid having to figure out the new role. > It will soon be able to follow what nested_{vmx,svm}_load_cr3 are doing, > and avoid unloading all the cached roots. > > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/mmu/mmu.c | 37 +++++++++++++++++-------------------- > arch/x86/kvm/svm/nested.c | 6 +++--- > arch/x86/kvm/vmx/nested.c | 6 +++--- > 3 files changed, 23 insertions(+), 26 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index da324a317000..906a9244ad28 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -4903,9 +4903,8 @@ void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0, > > new_role = kvm_calc_shadow_npt_root_page_role(vcpu, ®s); > > - __kvm_mmu_new_pgd(vcpu, nested_cr3, new_role.base); > - > shadow_mmu_init_context(vcpu, context, ®s, new_role); > + __kvm_mmu_new_pgd(vcpu, nested_cr3, new_role.base); > } > EXPORT_SYMBOL_GPL(kvm_init_shadow_npt_mmu); > > @@ -4943,27 +4942,25 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly, > kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty, > execonly, level); > > - __kvm_mmu_new_pgd(vcpu, new_eptp, new_role.base); > - > - if (new_role.as_u64 == context->mmu_role.as_u64) > - return; > - > - context->mmu_role.as_u64 = new_role.as_u64; > + if (new_role.as_u64 != context->mmu_role.as_u64) { > + context->mmu_role.as_u64 = new_role.as_u64; > > - context->shadow_root_level = level; > + context->shadow_root_level = level; > > - context->ept_ad = accessed_dirty; > - context->page_fault = ept_page_fault; > - context->gva_to_gpa = ept_gva_to_gpa; > - context->sync_page = ept_sync_page; > - context->invlpg = ept_invlpg; > - context->root_level = level; > - context->direct_map = false; > + context->ept_ad = accessed_dirty; > + context->page_fault = ept_page_fault; > + context->gva_to_gpa = ept_gva_to_gpa; > + context->sync_page = ept_sync_page; > + context->invlpg = ept_invlpg; > + context->root_level = level; > + context->direct_map = false; > + update_permission_bitmask(context, true); > + context->pkru_mask = 0; > + reset_rsvds_bits_mask_ept(vcpu, context, execonly, huge_page_level); > + reset_ept_shadow_zero_bits_mask(context, execonly); > + } > > - update_permission_bitmask(context, true); > - context->pkru_mask = 0; > - reset_rsvds_bits_mask_ept(vcpu, context, execonly, huge_page_level); > - reset_ept_shadow_zero_bits_mask(context, execonly); > + __kvm_mmu_new_pgd(vcpu, new_eptp, new_role.base); > } > EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu); > > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c > index f284e61451c8..96bab464967f 100644 > --- a/arch/x86/kvm/svm/nested.c > +++ b/arch/x86/kvm/svm/nested.c > @@ -492,14 +492,14 @@ static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, > CC(!load_pdptrs(vcpu, cr3))) > return -EINVAL; > > - if (!nested_npt) > - kvm_mmu_new_pgd(vcpu, cr3); > - > vcpu->arch.cr3 = cr3; > > /* Re-initialize the MMU, e.g. to pick up CR4 MMU role changes. */ > kvm_init_mmu(vcpu); > > + if (!nested_npt) > + kvm_mmu_new_pgd(vcpu, cr3); > + > return 0; > } > > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > index b7bc634d35e2..1dfe23963a9e 100644 > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -1126,15 +1126,15 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, > return -EINVAL; > } > > - if (!nested_ept) > - kvm_mmu_new_pgd(vcpu, cr3); > - > vcpu->arch.cr3 = cr3; > kvm_register_mark_dirty(vcpu, VCPU_EXREG_CR3); > > /* Re-initialize the MMU, e.g. to pick up CR4 MMU role changes. */ > kvm_init_mmu(vcpu); > > + if (!nested_ept) > + kvm_mmu_new_pgd(vcpu, cr3); > + > return 0; > } > Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky