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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 91BA3C43387 for ; Wed, 19 Dec 2018 16:25:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D79420869 for ; Wed, 19 Dec 2018 16:25:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729721AbeLSQZS (ORCPT ); Wed, 19 Dec 2018 11:25:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38494 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727790AbeLSQZR (ORCPT ); Wed, 19 Dec 2018 11:25:17 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AF26F7AEB1; Wed, 19 Dec 2018 16:25:17 +0000 (UTC) Received: from vitty.brq.redhat.com (unknown [10.43.2.155]) by smtp.corp.redhat.com (Postfix) with ESMTP id 24E01171F3; Wed, 19 Dec 2018 16:25:15 +0000 (UTC) From: Vitaly Kuznetsov To: kvm@vger.kernel.org Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , linux-kernel@vger.kernel.org, Tom Lendacky , Joerg Roedel Subject: [PATCH] KVM: x86: nSVM: fix switch to guest mmu Date: Wed, 19 Dec 2018 17:25:14 +0100 Message-Id: <20181219162514.30453-1-vkuznets@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 19 Dec 2018 16:25:17 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Recent optimizations in MMU code broke nested SVM with NPT in L1 completely: when we do nested_svm_{,un}init_mmu_context() we want to switch from TDP MMU to shadow MMU, both init_kvm_tdp_mmu() and kvm_init_shadow_mmu() check if re-configuration is needed by looking at cache source data. The data, however, doesn't change - it's only the type of the MMU which changes. We end up not re-initializing guest MMU as shadow and everything goes off the rails. The issue could have been fixed by putting MMU type into extended MMU role but this is not really needed. We can just split root and guest MMUs the exact same way we did for nVMX, their types never change in the lifetime of a vCPU. There is still room for improvement: currently, we reset all MMU roots when switching from L1 to L2 and back and this is not needed. Fixes: 7dcd57552008 ("x86/kvm/mmu: check if tdp/shadow MMU reconfiguration is needed") Signed-off-by: Vitaly Kuznetsov --- arch/x86/kvm/svm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index b78c691adea2..38821b0b78da 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -2923,6 +2923,8 @@ static void nested_svm_inject_npf_exit(struct kvm_vcpu *vcpu, static void nested_svm_init_mmu_context(struct kvm_vcpu *vcpu) { WARN_ON(mmu_is_nested(vcpu)); + + vcpu->arch.mmu = &vcpu->arch.guest_mmu; kvm_init_shadow_mmu(vcpu); vcpu->arch.mmu->set_cr3 = nested_svm_set_tdp_cr3; vcpu->arch.mmu->get_cr3 = nested_svm_get_tdp_cr3; @@ -2935,6 +2937,7 @@ static void nested_svm_init_mmu_context(struct kvm_vcpu *vcpu) static void nested_svm_uninit_mmu_context(struct kvm_vcpu *vcpu) { + vcpu->arch.mmu = &vcpu->arch.root_mmu; vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; } @@ -3444,7 +3447,6 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa, svm->vcpu.arch.hflags &= ~HF_HIF_MASK; if (nested_vmcb->control.nested_ctl & SVM_NESTED_CTL_NP_ENABLE) { - kvm_mmu_unload(&svm->vcpu); svm->nested.nested_cr3 = nested_vmcb->control.nested_cr3; nested_svm_init_mmu_context(&svm->vcpu); } -- 2.19.2