From patchwork Sat Oct 9 02:12:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 12546939 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E52F2C4332F for ; Sat, 9 Oct 2021 02:16:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF11760F51 for ; Sat, 9 Oct 2021 02:16:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244650AbhJICSa (ORCPT ); Fri, 8 Oct 2021 22:18:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38360 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244317AbhJICSD (ORCPT ); Fri, 8 Oct 2021 22:18:03 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32225C06135B for ; Fri, 8 Oct 2021 19:14:11 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id t7-20020a258387000000b005b6d7220c79so14966719ybk.16 for ; Fri, 08 Oct 2021 19:14:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=6xwGp+yCPRNZeLMFXXBjBMcyDDhJc3kOdh7+GdwoBtU=; b=O3uyycCB0m4rETPo/2EXg7KzDS0Kxxd5QSMOgN5++pIlRXIKx8d0yrsAd7IRsknDXU jfPpfSaBpR+vzVZLfe2k/aYazJeb1V2OYVJeM9zHGQGZhxYlUVKxD+cBCI62fGJRZVEl yp3sVQ08Q330CkbJTchqmDuBifPyeL6Ww3QjU3eQOha0KDm0IBJuDzOMnyesSyo+q+I/ lJ8xG8ZB8d3AYNpLPtB4eWA/pyqYaGmh5tBZ/8rId9AshkSUfwuM0AAs41HY+kSD+IsV W4/ngk/MxUvX4B342qXh08T69yL8VAymitYL9u6x/enfR2SkDRVs3Yd1g27SdUPXsZPn 0GRA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=6xwGp+yCPRNZeLMFXXBjBMcyDDhJc3kOdh7+GdwoBtU=; b=dmfNI0RuLF5nG6bYS+3u+9PwAyURqurZLCjDxDm9S7bMrUBiitmQPqpOrsfOtLXfmP pjK/jFEBkF8/Veh/MjhJ6roZwj5dQjYucIzHuphWFm8GaoZAb6kiBNcRyofYvbGYP0tQ XwdqzBiTcgb5efowRGbXVdw8t1y+pAgdf+iOFMbrJEY8nI11bg1Ml+HKtVImOkcbt7Jv 2dM0h76Omxb+uHd1IvvM78k/PC6FKunnP5WuxELg0ODn5rfzC/mYYj8SUJMPmCnJCGF6 jX9b/cGCurQ5xI6PTp0uSJNTVkbBV9w5r5Z+UVqjznzCtv4K24jrxo/euueY4I5LLQ2Z g/4A== X-Gm-Message-State: AOAM532K0mZjA4Mu+XibvONZ2UzNQ2h5cJxhiLcmVVu84B3xqRxlWeWu kizwAfI6PcHc0oMnZcis8LCq8uBZg5U= X-Google-Smtp-Source: ABdhPJxGMQ2uf1Tp63zXiZ9a6+eAt9/mXxTl51gnqbi9PaWar+CNyJX66rPwqvsO9Gv4EvKTMkdMfFkjiGQ= X-Received: from seanjc798194.pdx.corp.google.com ([2620:15c:90:200:e39b:6333:b001:cb]) (user=seanjc job=sendgmr) by 2002:a05:6902:154f:: with SMTP id r15mr8259463ybu.379.1633745650411; Fri, 08 Oct 2021 19:14:10 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 8 Oct 2021 19:12:29 -0700 In-Reply-To: <20211009021236.4122790-1-seanjc@google.com> Message-Id: <20211009021236.4122790-37-seanjc@google.com> Mime-Version: 1.0 References: <20211009021236.4122790-1-seanjc@google.com> X-Mailer: git-send-email 2.33.0.882.g93a45727a2-goog Subject: [PATCH v2 36/43] KVM: SVM: Don't bother checking for "running" AVIC when kicking for IPIs From: Sean Christopherson To: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Paul Mackerras , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Paolo Bonzini Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Atish Patra , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , Oliver Upton , Jing Zhang Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Drop the avic_vcpu_is_running() check when waking vCPUs in response to a VM-Exit due to incomplete IPI delivery. The check isn't wrong per se, but it's not 100% accurate in the sense that it doesn't guarantee that the vCPU was one of the vCPUs that didn't receive the IPI. The check isn't required for correctness as blocking == !running in this context. From a performance perspective, waking a live task is not expensive as the only moderately costly operation is a locked operation to temporarily disable preemption. And if that is indeed a performance issue, kvm_vcpu_is_blocking() would be a better check than poking into the AVIC. Signed-off-by: Sean Christopherson Reviewed-by: Maxim Levitsky --- arch/x86/kvm/svm/avic.c | 15 +++++++++------ arch/x86/kvm/svm/svm.h | 11 ----------- 2 files changed, 9 insertions(+), 17 deletions(-) diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index cbf02e7e20d0..b43b05610ade 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -295,13 +295,16 @@ static void avic_kick_target_vcpus(struct kvm *kvm, struct kvm_lapic *source, struct kvm_vcpu *vcpu; int i; + /* + * Wake any target vCPUs that are blocking, i.e. waiting for a wake + * event. There's no need to signal doorbells, as hardware has handled + * vCPUs that were in guest at the time of the IPI, and vCPUs that have + * since entered the guest will have processed pending IRQs at VMRUN. + */ kvm_for_each_vcpu(i, vcpu, kvm) { - bool m = kvm_apic_match_dest(vcpu, source, - icrl & APIC_SHORT_MASK, - GET_APIC_DEST_FIELD(icrh), - icrl & APIC_DEST_MASK); - - if (m && !avic_vcpu_is_running(vcpu)) + if (kvm_apic_match_dest(vcpu, source, icrl & APIC_SHORT_MASK, + GET_APIC_DEST_FIELD(icrh), + icrl & APIC_DEST_MASK)) kvm_vcpu_wake_up(vcpu); } } diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 0d7bbe548ac3..7f5b01bbee29 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -509,17 +509,6 @@ extern struct kvm_x86_nested_ops svm_nested_ops; #define VMCB_AVIC_APIC_BAR_MASK 0xFFFFFFFFFF000ULL -static inline bool avic_vcpu_is_running(struct kvm_vcpu *vcpu) -{ - struct vcpu_svm *svm = to_svm(vcpu); - u64 *entry = svm->avic_physical_id_cache; - - if (!entry) - return false; - - return (READ_ONCE(*entry) & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK); -} - int avic_ga_log_notifier(u32 ga_tag); void avic_vm_destroy(struct kvm *kvm); int avic_vm_init(struct kvm *kvm);