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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 7CA8FC433DF for ; Tue, 19 May 2020 21:13:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 603A7207D4 for ; Tue, 19 May 2020 21:13:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727983AbgESVNe (ORCPT ); Tue, 19 May 2020 17:13:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727803AbgESVNa (ORCPT ); Tue, 19 May 2020 17:13:30 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CCF26C08C5C0; Tue, 19 May 2020 14:13:29 -0700 (PDT) Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jb9Y4-0001wu-6B; Tue, 19 May 2020 23:13:16 +0200 Received: from nanos.tec.linutronix.de (localhost [IPv6:::1]) by nanos.tec.linutronix.de (Postfix) with ESMTP id B14A2100D00; Tue, 19 May 2020 23:13:15 +0200 (CEST) Message-Id: <20200519211224.286191418@linutronix.de> User-Agent: quilt/0.65 Date: Tue, 19 May 2020 22:31:29 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Paolo Bonzini , kvm@vger.kernel.org, Alexandre Chartre , Peter Zijlstra , Juergen Gross , Tom Lendacky Subject: [patch 1/7] x86/kvm: Move context tracking where it belongs References: <20200519203128.773151484@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Context tracking for KVM happens way too early in the vcpu_run() code. Anything after guest_enter_irqoff() and before guest_exit_irqoff() cannot use RCU and should also be not instrumented. The current way of doing this covers way too much code. Move it closer to the actual vmenter/exit code. Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Acked-by: Peter Zijlstra Acked-by: Paolo Bonzini Link: https://lkml.kernel.org/r/20200505134341.379326289@linutronix.de diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 4e9cd2a73ad0..40242e0af20d 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3389,6 +3389,14 @@ static fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) */ x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl); + /* + * Tell context tracking that this CPU is about to enter guest + * mode. This has to be after x86_spec_ctrl_set_guest() because + * that can take locks (lockdep needs RCU) and calls into world and + * some more. + */ + guest_enter_irqoff(); + __svm_vcpu_run(svm->vmcb_pa, (unsigned long *)&svm->vcpu.arch.regs); #ifdef CONFIG_X86_64 @@ -3399,6 +3407,14 @@ static fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) loadsegment(gs, svm->host.gs); #endif #endif + /* + * Tell context tracking that this CPU is back. + * + * This needs to be done before the below as native_read_msr() + * contains a tracepoint and x86_spec_ctrl_restore_host() calls + * into world and some more. + */ + guest_exit_irqoff(); /* * We do not use IBRS in the kernel. If this vCPU has used the diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 6a03c27ff314..ad0159f68ce4 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6724,6 +6724,11 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu) */ x86_spec_ctrl_set_guest(vmx->spec_ctrl, 0); + /* + * Tell context tracking that this CPU is about to enter guest mode. + */ + guest_enter_irqoff(); + /* L1D Flush includes CPU buffer clear to mitigate MDS */ if (static_branch_unlikely(&vmx_l1d_should_flush)) vmx_l1d_flush(vcpu); @@ -6739,6 +6744,11 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu) vcpu->arch.cr2 = read_cr2(); /* + * Tell context tracking that this CPU is back. + */ + guest_exit_irqoff(); + + /* * We do not use IBRS in the kernel. If this vCPU has used the * SPEC_CTRL MSR it may have left it on; save the value and * turn it off. This is much more efficient than blindly adding diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 471fccf7f850..28663a6688d1 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8438,7 +8438,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) } trace_kvm_entry(vcpu->vcpu_id); - guest_enter_irqoff(); fpregs_assert_state_consistent(); if (test_thread_flag(TIF_NEED_FPU_LOAD)) @@ -8500,7 +8499,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) local_irq_disable(); kvm_after_interrupt(vcpu); - guest_exit_irqoff(); if (lapic_in_kernel(vcpu)) { s64 delta = vcpu->arch.apic->lapic_timer.advance_expire_delta; if (delta != S64_MIN) {