From patchwork Fri Jan 6 01:12:48 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 39867 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:4e01:0:0:0:0:0 with SMTP id p1csp577094wrt; Thu, 5 Jan 2023 17:16:21 -0800 (PST) X-Google-Smtp-Source: AMrXdXscfq3lmvUIALZxpE6I+mJ9z6rvEl9KYE4cvgV6dQZkd1eOKlIm1+u8aBaHtkpIOgBcmBgb X-Received: by 2002:a05:6402:249a:b0:45c:834b:f287 with SMTP id q26-20020a056402249a00b0045c834bf287mr47016714eda.4.1672967781201; Thu, 05 Jan 2023 17:16:21 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1672967781; cv=none; d=google.com; s=arc-20160816; b=RbTgwA+Kc+SNv/kfNNuJp2xXf8gRpEEL7mjdH08zUTsKkpOsCa8SVA7QEpycQbTGq8 wyKc0+FdHcV7dTi6zVdkoKsGYHqAcoFc4NuAvRl1egQ2mSpnE0LB/lQDYOwcGcqXfjZX hC7rVS3aHVXG7EZ7IUq1sFiGk0V0h8FDKEbyZvguBcDbAu9yam5oUy73g9MOQs6LyAiV 1MCF8x1WcO4kQafOlCybDaFT5M8gRfwwS5u+XfbgkMLXI1IajlUTJb58eOkBwwVIQGEw MDRYtTmif+wba6CO4B+YUX1wE5+NaJe/kJg966s3G9/wIkS2aFghdGOT2RKeeG98mhVc 3Y8g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:reply-to:dkim-signature; bh=+aYaKFD5zMoXFl3Mrpqz5yT+Tj9hEBdwhn1YhcxYDeU=; b=fgc5LopkOgn310HSFcOsk3u4d92x6P84LDxUgZJ0QzHu+zrU4NdmrQk1huo+Kjsxlk KXSCxSd755HT4WYB4CX9D+iCYS+aAs50zjSVyek2TsAIn8lRmxQYfc+zG3VITAkzx3Gb bRMFtl+fvYbXzKazAgyHFNro11pYdD1UZGJQmJgJCxJs25kxv++SaxXqjlB469usxBmg 4IeGF1Owmk8MKROS45BH2cBLuQiE8MU7Iupe+5104wBNQBxB9ZzShckLqSeQ39bRuUV2 Kl4XC6bHovKKbrXwwFm2dKLYzG2aea+PKuajd6365JPUDeBJAd4saPwPdPVY4Wm6Grdw /Neg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=sVrsJnqL; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id v1-20020a056402348100b004511d552be3si39128466edc.4.2023.01.05.17.15.57; Thu, 05 Jan 2023 17:16:21 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=sVrsJnqL; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230477AbjAFBOp (ORCPT + 99 others); Thu, 5 Jan 2023 20:14:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236864AbjAFBNl (ORCPT ); Thu, 5 Jan 2023 20:13:41 -0500 Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09CFA72D1A for ; Thu, 5 Jan 2023 17:13:40 -0800 (PST) Received: by mail-pg1-x549.google.com with SMTP id s76-20020a632c4f000000b0049ceb0f185eso209927pgs.7 for ; Thu, 05 Jan 2023 17:13:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=+aYaKFD5zMoXFl3Mrpqz5yT+Tj9hEBdwhn1YhcxYDeU=; b=sVrsJnqLgRkQyST7umHC5BB4qxL1l41vI7qq4E+/x2fYGDtl5AblzcCHBALLb9sRU2 ri/9ceRv5yQOzb3I+MmQ3K1QAJGXYtF1Y4wKvQgdg92ouBF5eFn7dTG1dhyfPIaqfNya TtWAEjejrgGg4APj5FxYfagDJ/CSY7RVZ3U4SuZnL+FCbmpn1Z0CShem1/ETEBsadwyt q2k7WmsXJhirwxtI6qS8NTr7kOKbg63MA7fFnTq0fgXqguYnYjo331l4d5XiadWpW5Ye 8DaMyvexx2ci4k40Bay6fKvVXBqel9Gu10bgBFLXHp4mCFYpcUuvkphUhvN6nqw7lctd sOqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=+aYaKFD5zMoXFl3Mrpqz5yT+Tj9hEBdwhn1YhcxYDeU=; b=Nqke4zypgPJpU7Ewvju31NALpKMJVkN2s6PqI76X7LBROo5ZBf1booc3ZDM8PAkVMx VTndwR2ZuqKjRVeefuWk9zYdvKaYM7b8XKZUJZHf1J4I2CTcIFgZ9+Glr3kUCZXasj9g gZOOJnUauvIouCegJFmwajXtK1CJXH41qXfjijYmOuci9eRzEvDORZIFVewI80AwoILE yLaEK+gj/ORcOx1iy9xpjfK7tiRLjVqO0d1nON0TeJPQkdP8SlbKR2UEWoK6y4CryM6m L+s8HBCLgdOh1c3OZx1KIvPsvxLGTdTWv5eM0zJqc9m2CzmRbGyLfj7q+uaMjY68tkyj H68A== X-Gm-Message-State: AFqh2krVkufRW0+BJ/VHjm+cUKrzV0lcPkejp3Vyw2uTA0pVmaNLN6zW c1Paeh3ZOYIgeDjyFLPiIqG5R3D+gUI= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a62:1c4d:0:b0:581:1898:93ae with SMTP id c74-20020a621c4d000000b00581189893aemr2945460pfc.51.1672967619557; Thu, 05 Jan 2023 17:13:39 -0800 (PST) Reply-To: Sean Christopherson Date: Fri, 6 Jan 2023 01:12:48 +0000 In-Reply-To: <20230106011306.85230-1-seanjc@google.com> Mime-Version: 1.0 References: <20230106011306.85230-1-seanjc@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230106011306.85230-16-seanjc@google.com> Subject: [PATCH v5 15/33] KVM: SVM: Document that vCPU ID == APIC ID in AVIC kick fastpatch From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Alejandro Jimenez , Maxim Levitsky , Suravee Suthikulpanit , Li RongQing , Greg Edwards X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1754233864286684883?= X-GMAIL-MSGID: =?utf-8?q?1754233864286684883?= Document that AVIC is inhibited if any vCPU's APIC ID diverges from its vCPU ID, i.e. that there's no need to check for a destination match in the AVIC kick fast path. Opportunistically tweak comments to remove "guest bug", as that suggests KVM is punting on error handling, which is not the case. Targeting a non-existent vCPU or no vCPUs _may_ be a guest software bug, but whether or not it's a guest bug is irrelevant. Such behavior is architecturally legal and thus needs to faithfully emulated by KVM (and it is). Signed-off-by: Sean Christopherson Reviewed-by: Maxim Levitsky --- arch/x86/kvm/svm/avic.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index e4b5f8b14882..eb2ad5b54877 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -368,8 +368,8 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source cluster = (dest >> 4) << 2; } + /* Nothing to do if there are no destinations in the cluster. */ if (unlikely(!bitmap)) - /* guest bug: nobody to send the logical interrupt to */ return 0; if (!is_power_of_2(bitmap)) @@ -397,7 +397,7 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source if (WARN_ON_ONCE(index != logid_index)) return -EINVAL; - /* guest bug: non existing/reserved logical destination */ + /* Nothing to do if the logical destination is invalid. */ if (unlikely(!(logid_entry & AVIC_LOGICAL_ID_ENTRY_VALID_MASK))) return 0; @@ -406,9 +406,13 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source } } + /* + * KVM inhibits AVIC if any vCPU ID diverges from the vCPUs APIC ID, + * i.e. APIC ID == vCPU ID. Once again, nothing to do if the target + * vCPU doesn't exist. + */ target_vcpu = kvm_get_vcpu_by_id(kvm, l1_physical_id); if (unlikely(!target_vcpu)) - /* guest bug: non existing vCPU is a target of this IPI*/ return 0; target_vcpu->arch.apic->irr_pending = true;