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, 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 D3E95C433F5 for ; Thu, 16 Sep 2021 18:56:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B7F6960E08 for ; Thu, 16 Sep 2021 18:56:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343782AbhIPS6A (ORCPT ); Thu, 16 Sep 2021 14:58:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51676 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245671AbhIPS5a (ORCPT ); Thu, 16 Sep 2021 14:57:30 -0400 Received: from mail-qv1-xf4a.google.com (mail-qv1-xf4a.google.com [IPv6:2607:f8b0:4864:20::f4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A13AC04A159 for ; Thu, 16 Sep 2021 11:15:49 -0700 (PDT) Received: by mail-qv1-xf4a.google.com with SMTP id r18-20020a056214069200b0037a291a6081so63338396qvz.18 for ; Thu, 16 Sep 2021 11:15:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=kz3OtxRFyvuoMc+GBdo3WelMyguFcbw6nvQK4NKbTKo=; b=WGjrebjRTcERQwIM8hSLM7Nl5SVAOazwDndoUi9mjyNGkCx02qOHis4a1hPszhq0yW Hpks5WNyxwB/kMmupaieFv3feod8Wdj0B75fYzVvYKmlfFMCSpPeDxRIS+Aa/ODBqSIE hpy6lg5Dx2K7qebKQQ13Fn6X7I55PjoakM4zKMArOaD14HZ/KFbrRTx+vhAhJBeFR4YI rJ04K4maFwajOHK2c7o8CmX2izEPYvVchseyrggB+NJRzs7hghKXo7nPzRWu4qIPajs7 vIDtLSVoJTB9QMBi2AJIevhOF/EgVIob83DLDBKfYj2DEaTzF1zs3va4+qd8WE3NeXba uxKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=kz3OtxRFyvuoMc+GBdo3WelMyguFcbw6nvQK4NKbTKo=; b=kfSX7ESuB9H/eQgb2hcbWUKFPGQfpnfScrOB8KmQewVrBhNp/F4PLWtW/W5JOa/axM Wo42CrGQmPfuyT3qDAkHA3jSEQ9UtSevYw8lBwFq0v0na/k/sjWsz1tFDnOGbIkZEaOM eMJ8gU20AmopyRyl1TI/zdlO2BGLO0wyoefFIf1EntthTwbXv1oortTmpJUr2R5cRIpS CTcn9MQG9Io9vbCzbKCMw7cYF2wRJQNTNy0LUz3Nvacyi8qO029pqu8KGwitJ4HX0rZB RemFlO3lyCOnvGrgbNjve/iKTt7m+m4qC26rjphkf66QxK7DZIlTinViKdlN17lhYUi1 BMCQ== X-Gm-Message-State: AOAM530TMu1sg4Y7BxEqBwB4rr3jOZc3PW4Z4lWsbH+TStxh+FtPTb54 eCilPwsC0nwcHGWyvfHRb5aoAMFNYb4trBOcF/UxljrWWZP5i2wOnr5i/HBMTaw5aUg88m7BspV GvcSXc4tQN25zoE+rHqdS5hm9melrVjP9QTNPVtunLQaEOhOGtHQ7LexeNw== X-Google-Smtp-Source: ABdhPJxkIq2pjE4hQkHq1iuBeO8+WA+QPDKfz8Iecr8PSvZkKcaqo8w22TSP1+JhIpwxYCAaCvA+D8YErlY= X-Received: from oupton.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:404]) (user=oupton job=sendgmr) by 2002:a25:1345:: with SMTP id 66mr8429706ybt.502.1631816148619; Thu, 16 Sep 2021 11:15:48 -0700 (PDT) Date: Thu, 16 Sep 2021 18:15:37 +0000 In-Reply-To: <20210916181538.968978-1-oupton@google.com> Message-Id: <20210916181538.968978-7-oupton@google.com> Mime-Version: 1.0 References: <20210916181538.968978-1-oupton@google.com> X-Mailer: git-send-email 2.33.0.464.g1972c5931b-goog Subject: [PATCH v8 6/7] KVM: x86: Refactor tsc synchronization code From: Oliver Upton To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Cc: Paolo Bonzini , Sean Christopherson , Marc Zyngier , Peter Shier , Jim Mattson , David Matlack , Ricardo Koller , Jing Zhang , Raghavendra Rao Anata , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, Andrew Jones , Will Deacon , Catalin Marinas , Oliver Upton Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Refactor kvm_synchronize_tsc to make a new function that allows callers to specify TSC parameters (offset, value, nanoseconds, etc.) explicitly for the sake of participating in TSC synchronization. Signed-off-by: Oliver Upton --- arch/x86/kvm/x86.c | 100 ++++++++++++++++++++++++++------------------- 1 file changed, 58 insertions(+), 42 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 29156c49cd11..1ea65bb2e74d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2447,13 +2447,68 @@ static inline bool kvm_check_tsc_unstable(void) return check_tsc_unstable(); } +/* + * Infers attempts to synchronize the guest's tsc from host writes. Sets the + * offset for the vcpu and tracks the TSC matching generation that the vcpu + * participates in. + */ +static void __kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 offset, u64 tsc, + u64 ns, bool matched) +{ + struct kvm *kvm = vcpu->kvm; + bool already_matched; + + lockdep_assert_held(&kvm->arch.tsc_write_lock); + + already_matched = + (vcpu->arch.this_tsc_generation == kvm->arch.cur_tsc_generation); + + /* + * We also track th most recent recorded KHZ, write and time to + * allow the matching interval to be extended at each write. + */ + kvm->arch.last_tsc_nsec = ns; + kvm->arch.last_tsc_write = tsc; + kvm->arch.last_tsc_khz = vcpu->arch.virtual_tsc_khz; + + vcpu->arch.last_guest_tsc = tsc; + + /* Keep track of which generation this VCPU has synchronized to */ + vcpu->arch.this_tsc_generation = kvm->arch.cur_tsc_generation; + vcpu->arch.this_tsc_nsec = kvm->arch.cur_tsc_nsec; + vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write; + + kvm_vcpu_write_tsc_offset(vcpu, offset); + + if (!matched) { + /* + * We split periods of matched TSC writes into generations. + * For each generation, we track the original measured + * nanosecond time, offset, and write, so if TSCs are in + * sync, we can match exact offset, and if not, we can match + * exact software computation in compute_guest_tsc() + * + * These values are tracked in kvm->arch.cur_xxx variables. + */ + kvm->arch.cur_tsc_generation++; + kvm->arch.cur_tsc_nsec = ns; + kvm->arch.cur_tsc_write = tsc; + kvm->arch.cur_tsc_offset = offset; + + kvm->arch.nr_vcpus_matched_tsc = 0; + } else if (!already_matched) { + kvm->arch.nr_vcpus_matched_tsc++; + } + + kvm_track_tsc_matching(vcpu); +} + static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data) { struct kvm *kvm = vcpu->kvm; u64 offset, ns, elapsed; unsigned long flags; - bool matched; - bool already_matched; + bool matched = false; bool synchronizing = false; raw_spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags); @@ -2499,48 +2554,9 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data) offset = kvm_compute_l1_tsc_offset(vcpu, data); } matched = true; - already_matched = (vcpu->arch.this_tsc_generation == kvm->arch.cur_tsc_generation); - } else { - /* - * We split periods of matched TSC writes into generations. - * For each generation, we track the original measured - * nanosecond time, offset, and write, so if TSCs are in - * sync, we can match exact offset, and if not, we can match - * exact software computation in compute_guest_tsc() - * - * These values are tracked in kvm->arch.cur_xxx variables. - */ - kvm->arch.cur_tsc_generation++; - kvm->arch.cur_tsc_nsec = ns; - kvm->arch.cur_tsc_write = data; - kvm->arch.cur_tsc_offset = offset; - matched = false; } - /* - * We also track th most recent recorded KHZ, write and time to - * allow the matching interval to be extended at each write. - */ - kvm->arch.last_tsc_nsec = ns; - kvm->arch.last_tsc_write = data; - kvm->arch.last_tsc_khz = vcpu->arch.virtual_tsc_khz; - - vcpu->arch.last_guest_tsc = data; - - /* Keep track of which generation this VCPU has synchronized to */ - vcpu->arch.this_tsc_generation = kvm->arch.cur_tsc_generation; - vcpu->arch.this_tsc_nsec = kvm->arch.cur_tsc_nsec; - vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write; - - kvm_vcpu_write_tsc_offset(vcpu, offset); - - if (!matched) { - kvm->arch.nr_vcpus_matched_tsc = 0; - } else if (!already_matched) { - kvm->arch.nr_vcpus_matched_tsc++; - } - - kvm_track_tsc_matching(vcpu); + __kvm_synchronize_tsc(vcpu, offset, data, ns, matched); raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); } -- 2.33.0.309.g3052b89438-goog