From patchwork Mon Aug 16 00:11:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Upton X-Patchwork-Id: 12437451 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=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 2D79EC4338F for ; Mon, 16 Aug 2021 00:15:02 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E3D9A6137D for ; Mon, 16 Aug 2021 00:15:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E3D9A6137D Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:References: Mime-Version:Message-Id:In-Reply-To:Date:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=v7pWGrPGWF5jSDX45s7cqH2QCqYcijm4GbkYfOqOisQ=; b=lBIszEBalwjPpzeHsHXsT/gfCF tgUR61Zpo+do0cg8L+hxrGU1cLiuMHc5ZIQQneY5A0HzfonXWM9JVtHxm5qST655R08fMhKvwwA71 qJ7vDVGjkpl7ws0GnpJBK0rgD9vFMYdB4A+nlNv45Zs4Ovy3Y4OtKWATv4wd3ocI4UBcbgcgEumNX aXtvF6CYsnxIDAHC7Y8/iLz87lGVJ2upVWPZ94LY3QCay3yarGH8kEbSrJ+de/MdksdygsiSC5UFQ hOb4A0rJXdtF6OE9L57UiqBIqA0zEMooTU3jMQZgKqsxugl4SdMlCC1/OancQBsvy0H0NX4EjcsBx +02Gn9+A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mFQF2-00FlFX-AL; Mon, 16 Aug 2021 00:12:36 +0000 Received: from mail-yb1-xb49.google.com ([2607:f8b0:4864:20::b49]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mFQE9-00Fl7x-2Z for linux-arm-kernel@lists.infradead.org; Mon, 16 Aug 2021 00:11:42 +0000 Received: by mail-yb1-xb49.google.com with SMTP id i32-20020a25b2200000b02904ed415d9d84so15005824ybj.0 for ; Sun, 15 Aug 2021 17:11:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=Dz4OQO7fko2xnm4bF9gtGHyuF6byVH0iKDoKQ9+K0Hk=; b=nG02hDlOtRC4KMB166Vy/WGh+WM1WqWLqoL9SZhFphHrdt7+VGLAwmWCuohkTHG09W qutphgh99ADbQ04rhvA8LKDsAP+PLuBGZVfX6CsIlwTBHn6j1ge13dmrDOQc/smYQfij KPWPWRIVRlB3EriEo/xoctVVzJUObu/x7xovD9XeuNYhRk6uYKiZw+BV5pFtGdV9a4tc nvsgIvqHBuviNCQWPM8HO56W+tOa30KchZXhGEeUXYEC/ZDclh79E9PPgJx/+wcbJCHb /w6w1lECCO5Ja8sYwFNhywkGt3KmcdRiSDJcb6AlSJRaOymWy44wwnqT4ZcbZ+U1s16l nAag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=Dz4OQO7fko2xnm4bF9gtGHyuF6byVH0iKDoKQ9+K0Hk=; b=MKSCw5ZdWXnIL6JkC2sTjK/39lKvk6fgRdv5gBsusMuFQQTP7lk6kGU7agWGqIM1Ya FKXJGxA71kutPNey7V85XAho6IAD44qq5146q//B2U3vYR4oAPSZfC7zPgMyvgwYkGPs ZuQIh9Bdnyq+RElnfyiYv1tq9O9EOreHs91lLGbjVhOCN9ol7B3lSgMmx0baSHPLQ+mG YaiLC2C+lIURfcCebPk8iYqdhPHv7koUa0cUVVFxd5nnXGBQQjEl1nMgb0jeiNzvJmSg 9+/YyAjqqCmisk2hZaLWIHS1o9fNqAtXUuf0pkNwxbi2F09Hmu4L9ZNTULrISzTW+mDG V4Bw== X-Gm-Message-State: AOAM530By3dT5MWdrrADk9FyhT6nKeYCT3CBIIJRA/qkWZWBK8WcLOLH C6ppQZm693UG1Y1j1UAvr//X0OciEhc= X-Google-Smtp-Source: ABdhPJz9cl6CBqtVJqMeLgOBubeEV1ZIVpCy0Cv8/HD8GcR/AFOkA5Fnz9sYJeChQ3DsMEpVB1XuZCGCFoc= X-Received: from oupton.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:404]) (user=oupton job=sendgmr) by 2002:a25:41ce:: with SMTP id o197mr18562489yba.365.1629072699675; Sun, 15 Aug 2021 17:11:39 -0700 (PDT) Date: Mon, 16 Aug 2021 00:11:29 +0000 In-Reply-To: <20210816001130.3059564-1-oupton@google.com> Message-Id: <20210816001130.3059564-6-oupton@google.com> Mime-Version: 1.0 References: <20210816001130.3059564-1-oupton@google.com> X-Mailer: git-send-email 2.33.0.rc1.237.g0d66db33f3-goog Subject: [PATCH v7 5/6] 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210815_171141_183279_696F1D7F X-CRM114-Status: GOOD ( 15.41 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 | 105 ++++++++++++++++++++++++++------------------- 1 file changed, 61 insertions(+), 44 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index f1434cd388b9..9d0445527dad 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2447,13 +2447,71 @@ 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 track the 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; + + spin_lock(&kvm->arch.pvclock_gtod_sync_lock); + kvm->arch.nr_vcpus_matched_tsc = 0; + } else if (!already_matched) { + spin_lock(&kvm->arch.pvclock_gtod_sync_lock); + kvm->arch.nr_vcpus_matched_tsc++; + } + + kvm_track_tsc_matching(vcpu); + spin_unlock(&kvm->arch.pvclock_gtod_sync_lock); +} + 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); @@ -2499,50 +2557,9 @@ 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); - - spin_lock_irqsave(&kvm->arch.pvclock_gtod_sync_lock, flags); - if (!matched) { - kvm->arch.nr_vcpus_matched_tsc = 0; - } else if (!already_matched) { - kvm->arch.nr_vcpus_matched_tsc++; - } - - kvm_track_tsc_matching(vcpu); - spin_unlock_irqrestore(&kvm->arch.pvclock_gtod_sync_lock, flags); + __kvm_synchronize_tsc(vcpu, offset, data, ns, matched); raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); }