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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 9E70DC43460 for ; Wed, 5 May 2021 00:27:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77E1C610A6 for ; Wed, 5 May 2021 00:27:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231561AbhEEA2w (ORCPT ); Tue, 4 May 2021 20:28:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50370 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231430AbhEEA2s (ORCPT ); Tue, 4 May 2021 20:28:48 -0400 Received: from mail-qt1-x84a.google.com (mail-qt1-x84a.google.com [IPv6:2607:f8b0:4864:20::84a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7BFFEC061574 for ; Tue, 4 May 2021 17:27:52 -0700 (PDT) Received: by mail-qt1-x84a.google.com with SMTP id j3-20020ac874c30000b02901bab5879d6aso15615qtr.0 for ; Tue, 04 May 2021 17:27:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=h6JK13NBo79kgeijdsl/XACOJNOEDrS1vfGEPF8K2m8=; b=bBMrJre9BppTYU+GNRG3AcJK4VcCnP4ndqYIZ8cIXc32UMWnproV0PttLueCPJWppp dQSldY9G967LvyULabNPnmEWAqas6yiX9nbNlQAfmWg8r6t4p7ePRYdocTxAqdTbTWBo 20T/G6U3OGPS1QzpTGiCLd+QmPhMzcCtydAtQSs0Ugkv/A5Jf0uUe/icOGrwI7NuU4wD xHVMDxkwnbFaN64wTsUdO96MwFCSGiGxCEAN4DuSVCC/hTyjNTG6NrH83Q4El5cH6Dg8 qVOchLPYlWuRSDzaOs5Q6h2TCoO/wh2R3Ahw6Wvg3kj6M5w/OGpQ/sArpJ/zs3G9WCad fPvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=h6JK13NBo79kgeijdsl/XACOJNOEDrS1vfGEPF8K2m8=; b=EiLqQJrlT15s+95rPGMhQOQbzTRqVVMsnD6ntOwhKj74j1fCGibpBfC4lZTuFEODwt lLhvlr3M43xIj8a+xiCXO5jmP3TdSay5FD6ns6xUhLf6JIIXAk8spK/LyaRMTGeBUr/o zJG4VvSIGl0fpWhM785sf1xM5U1376Ceg1CqVFmqhhmSjOgnohZnHecfoXM6BL9xP2Sr hn4qZO926nduhy4pdQS8szNBHCiP/rGsAfkxHjqKMBTZHgWEgck+0u02MfosTxdwqkVu QrxpSrmvDhO5+jQhZdPppOt01TQHTVQSw46EJKgD1EGUPSgqP8SUHOPS4Y/YFkF3Isyb y5cA== X-Gm-Message-State: AOAM533SspOv8iPag+HqOUP183bMYApfygjeOlK2cqnQhw7pVKwxTLtH VCDgFeZZTuUXpE89gZcYPHmnimRZkYA= X-Google-Smtp-Source: ABdhPJxJ5Unb+wl1eR7T9l6AUF3aTSlpN9ha81MhtYYIDOPBCITlWA/zy0GMOZIoJvZaLCdxoYkHfwvRWl8= X-Received: from seanjc798194.pdx.corp.google.com ([2620:15c:f:10:df57:48cb:ea33:a156]) (user=seanjc job=sendgmr) by 2002:ad4:5588:: with SMTP id e8mr28253896qvx.10.1620174471714; Tue, 04 May 2021 17:27:51 -0700 (PDT) Reply-To: Sean Christopherson Date: Tue, 4 May 2021 17:27:30 -0700 In-Reply-To: <20210505002735.1684165-1-seanjc@google.com> Message-Id: <20210505002735.1684165-4-seanjc@google.com> Mime-Version: 1.0 References: <20210505002735.1684165-1-seanjc@google.com> X-Mailer: git-send-email 2.31.1.527.g47e6f16901-goog Subject: [PATCH v4 3/8] KVM: x86: Defer vtime accounting 'til after IRQ handling From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Michael Tokarev , Christian Borntraeger , Frederic Weisbecker Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wanpeng Li Defer the call to account guest time until after servicing any IRQ(s) that happened in the guest or immediately after VM-Exit. Tick-based accounting of vCPU time relies on PF_VCPU being set when the tick IRQ handler runs, and IRQs are blocked throughout the main sequence of vcpu_enter_guest(), including the call into vendor code to actually enter and exit the guest. This fixes a bug[*] where reported guest time remains '0', even when running an infinite loop in the guest. [*] https://bugzilla.kernel.org/show_bug.cgi?id=209831 Fixes: 87fa7f3e98a131 ("x86/kvm: Move context tracking where it belongs") Cc: Thomas Gleixner Cc: Sean Christopherson Cc: Michael Tokarev Cc: stable@vger.kernel.org#v5.9-rc1+ Suggested-by: Thomas Gleixner Signed-off-by: Wanpeng Li Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/svm.c | 6 +++--- arch/x86/kvm/vmx/vmx.c | 6 +++--- arch/x86/kvm/x86.c | 9 +++++++++ 3 files changed, 15 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index a7271f31df47..7dd63545526b 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3753,15 +3753,15 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu) * have them in state 'on' as recorded before entering guest mode. * Same as enter_from_user_mode(). * - * guest_exit_irqoff() restores host context and reinstates RCU if - * enabled and required. + * context_tracking_guest_exit() restores host context and reinstates + * RCU if enabled and required. * * 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. */ lockdep_hardirqs_off(CALLER_ADDR0); - guest_exit_irqoff(); + context_tracking_guest_exit(); instrumentation_begin(); trace_hardirqs_off_finish(); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 10b610fc7bbc..8425827068c3 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6701,15 +6701,15 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu, * have them in state 'on' as recorded before entering guest mode. * Same as enter_from_user_mode(). * - * guest_exit_irqoff() restores host context and reinstates RCU if - * enabled and required. + * context_tracking_guest_exit() restores host context and reinstates + * RCU if enabled and required. * * 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. */ lockdep_hardirqs_off(CALLER_ADDR0); - guest_exit_irqoff(); + context_tracking_guest_exit(); instrumentation_begin(); trace_hardirqs_off_finish(); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3bf52ba5f2bb..40e958617405 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9367,6 +9367,15 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) local_irq_disable(); kvm_after_interrupt(vcpu); + /* + * Wait until after servicing IRQs to account guest time so that any + * ticks that occurred while running the guest are properly accounted + * to the guest. Waiting until IRQs are enabled degrades the accuracy + * of accounting via context tracking, but the loss of accuracy is + * acceptable for all known use cases. + */ + vtime_account_guest_exit(); + if (lapic_in_kernel(vcpu)) { s64 delta = vcpu->arch.apic->lapic_timer.advance_expire_delta; if (delta != S64_MIN) { -- 2.31.1.527.g47e6f16901-goog