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 52FC6C433EF for ; Fri, 4 Feb 2022 11:57:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358511AbiBDL5Y (ORCPT ); Fri, 4 Feb 2022 06:57:24 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:56766 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230501AbiBDL5W (ORCPT ); Fri, 4 Feb 2022 06:57:22 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1643975842; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=I2DzmizRxymlu2fjBogBbGDUB/Xq+NvGxXpe5knoTEY=; b=gk1tXPv8cPApVyFFchhbOI12WlczWu8vS1bBcfhsFtAHIrujPv2mX53UmMpueSYoMfECbg DOcpqL4/bX8OZDSPA69V0/w/6ITC1XLSkFdJHJGBtSuQMuX1Dc6KcjBzIuq71TJhSsipcw pGGh3C7RUq7qwkzOAQOBB5TiANrAv+I= 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-639-uEoj1HErOwe7HQR6wLIpxA-1; Fri, 04 Feb 2022 06:57:20 -0500 X-MC-Unique: uEoj1HErOwe7HQR6wLIpxA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 71B34190B2A0; Fri, 4 Feb 2022 11:57:19 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id E77641081172; Fri, 4 Feb 2022 11:57:18 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: dmatlack@google.com, seanjc@google.com, vkuznets@redhat.com Subject: [PATCH 00/23] KVM: MMU: MMU role refactoring Date: Fri, 4 Feb 2022 06:56:55 -0500 Message-Id: <20220204115718.14934-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The TDP MMU has a performance regression compared to the legacy MMU when CR0 changes often. This was reported for the grsecurity kernel, which uses CR0.WP to implement kernel W^X. In that case, each change to CR0.WP unloads the MMU and causes a lot of unnecessary work. When running nested, this can even cause the L1 to hardly make progress, as the L0 hypervisor it is overwhelmed by the amount of MMU work that is needed. The root cause of the issue is that the "MMU role" in KVM is a mess that mixes the CPU setup (CR0/CR4/EFER, SMM, guest mode, etc.) and the shadow page table format. Whenever something is different between the MMU and the CPU, it is stored as an extra field in struct kvm_mmu---and for extra bonus complication, sometimes the same thing is stored in both the role and an extra field. So, this is the "no functional change intended" part of the changes required to fix the performance regression. It separates neatly the shadow page table format ("MMU role") from the guest page table format ("CPU role"), and removes the duplicate fields. The next step then is to avoid unloading the MMU as long as the MMU role stays the same. Please review! Paolo Paolo Bonzini (23): KVM: MMU: pass uses_nx directly to reset_shadow_zero_bits_mask KVM: MMU: nested EPT cannot be used in SMM KVM: MMU: remove valid from extended role KVM: MMU: constify uses of struct kvm_mmu_role_regs KVM: MMU: pull computation of kvm_mmu_role_regs to kvm_init_mmu KVM: MMU: load new PGD once nested two-dimensional paging is initialized KVM: MMU: remove kvm_mmu_calc_root_page_role KVM: MMU: rephrase unclear comment KVM: MMU: remove "bool base_only" arguments KVM: MMU: split cpu_role from mmu_role KVM: MMU: do not recompute root level from kvm_mmu_role_regs KVM: MMU: remove ept_ad field KVM: MMU: remove kvm_calc_shadow_root_page_role_common KVM: MMU: cleanup computation of MMU roles for two-dimensional paging KVM: MMU: cleanup computation of MMU roles for shadow paging KVM: MMU: remove extended bits from mmu_role KVM: MMU: remove redundant bits from extended role KVM: MMU: fetch shadow EFER.NX from MMU role KVM: MMU: simplify and/or inline computation of shadow MMU roles KVM: MMU: pull CPU role computation to kvm_init_mmu KVM: MMU: store shadow_root_level into mmu_role KVM: MMU: use cpu_role for root_level KVM: MMU: replace direct_map with mmu_role.direct arch/x86/include/asm/kvm_host.h | 13 +- arch/x86/kvm/mmu.h | 2 +- arch/x86/kvm/mmu/mmu.c | 408 ++++++++++++-------------------- arch/x86/kvm/mmu/mmu_audit.c | 6 +- arch/x86/kvm/mmu/paging_tmpl.h | 12 +- arch/86/kvm/mmu/tdp_mmu.c | 4 +- arch/x86/kvm/svm/svm.c | 2 +- arch/x86/kvm/vmx/vmx.c | 2 +- arch/x86/kvm/x86.c | 12 +- 10 files changed, 178 insertions(+), 284 deletions(-) -- 2.31.1