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 Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0E6C4C433FE for ; Thu, 9 Dec 2021 16:03:53 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 9A52E4121B; Thu, 9 Dec 2021 16:03:53 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 5MssuM_UdF3W; Thu, 9 Dec 2021 16:03:52 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp2.osuosl.org (Postfix) with ESMTPS id 0CEDE41210; Thu, 9 Dec 2021 16:03:51 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id D7BEEC001E; Thu, 9 Dec 2021 16:03:51 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [IPv6:2605:bc80:3010::138]) by lists.linuxfoundation.org (Postfix) with ESMTP id E0341C0012 for ; Thu, 9 Dec 2021 16:03:50 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id CEFCA80F8C for ; Thu, 9 Dec 2021 16:03:50 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp1.osuosl.org (amavisd-new); dkim=pass (1024-bit key) header.d=redhat.com Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id op5PNGjZF2Y4 for ; Thu, 9 Dec 2021 16:03:50 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by smtp1.osuosl.org (Postfix) with ESMTPS id 152B280F82 for ; Thu, 9 Dec 2021 16:03:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639065828; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=88wBNbW8beVEscjJxOr5QDERAx5Xra/tbkHKBTuW1TQ=; b=BRNS2RgzQCSvnoDz+dQdeu07N8LZJuD1LVmosrH/HCdqpoCVeld5VSy1mX/JQ6HIOQoHQP tJ877I+dtilHJsn0MjRRAwbx7pY/pmOV/MDplxwLMS6onXjTLpemosnv9s9Pww7WBJnYEl C1an6mlM1NM+j6AriAfjbNGB7yJmblo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-28-Yh2kklBbPKGEB2Q_VM82HA-1; Thu, 09 Dec 2021 11:03:45 -0500 X-MC-Unique: Yh2kklBbPKGEB2Q_VM82HA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6F65A101796A; Thu, 9 Dec 2021 16:03:44 +0000 (UTC) Received: from starship (unknown [10.40.192.24]) by smtp.corp.redhat.com (Postfix) with ESMTP id 57B326B8EA; Thu, 9 Dec 2021 16:03:41 +0000 (UTC) Message-ID: <84b493880aecfed52bed62714df77497c46af2ef.camel@redhat.com> Subject: Re: [PATCH v3 00/26] KVM: x86: Halt and APICv overhaul From: Maxim Levitsky To: Sean Christopherson Date: Thu, 09 Dec 2021 18:03:39 +0200 In-Reply-To: References: <20211208015236.1616697-1-seanjc@google.com> <39c885fc6455dd0aa2f8643e725422851430f9ec.camel@redhat.com> <8c6c38f3cc201e42629c3b8e5cf8cdb251c9ea8d.camel@redhat.com> <3bf8d500-0c1e-92dd-20c8-c3c231d2cbed@redhat.com> <346f5a5e93077ba20188a9b0e67bb3a44e2cad48.camel@redhat.com> User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Cc: Wanpeng Li , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Paolo Bonzini , Vitaly Kuznetsov , Jim Mattson X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Thu, 2021-12-09 at 15:45 +0000, Sean Christopherson wrote: > On Thu, Dec 09, 2021, Maxim Levitsky wrote: > > On Thu, 2021-12-09 at 15:29 +0100, Paolo Bonzini wrote: > > > On 12/9/21 01:02, Sean Christopherson wrote: > > > > RDX, a.k.a. ir_data is NULL. This check in svm_ir_list_add() > > > > > > > > if (pi->ir_data && (pi->prev_ga_tag != 0)) { > > > > > > > > implies pi->ir_data can be NULL, but neither avic_update_iommu_vcpu_affinity() > > > > nor amd_iommu_update_ga() check ir->data for NULL. > > > > > > > > amd_ir_set_vcpu_affinity() returns "success" without clearing pi.is_guest_mode > > > > > > > > /* Note: > > > > * This device has never been set up for guest mode. > > > > * we should not modify the IRTE > > > > */ > > > > if (!dev_data || !dev_data->use_vapic) > > > > return 0; > > > > > > > > so it's plausible svm_ir_list_add() could add to the list with a NULL pi->ir_data. > > > > > > > > But none of the relevant code has seen any meaningful changes since 5.15, so odds > > > > are good I broke something :-/ > > > > Doesn't reproduce here yet even with my iommu changes :-( > > Oh well. > > Hmm, which suggests it could be an existing corner case. Could very very be! Next Sunday I'll lean the AMD iommu code a bit closer, and see if I can spot more bugs in it. Best regards, Maxim Levitsky > > Based on the above, this seems prudent and correct: > > @@ -747,7 +754,7 @@ static int svm_ir_list_add(struct vcpu_svm *svm, struct amd_iommu_pi_data *pi) > * so we need to check here if it's already been * added > * to the ir_list. > */ > - if (pi->ir_data && (pi->prev_ga_tag != 0)) { > + if (pi->prev_ga_tag != 0) { > struct kvm *kvm = svm->vcpu.kvm; > u32 vcpu_id = AVIC_GATAG_TO_VCPUID(pi->prev_ga_tag); > struct kvm_vcpu *prev_vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id); > @@ -877,7 +884,7 @@ int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq, > * we can reference to them directly when we update vcpu > * scheduling information in IOMMU irte. > */ > - if (!ret && pi.is_guest_mode) > + if (!ret && pi.is_guest_mode && pi.ir_data) > svm_ir_list_add(svm, &pi); > } else { > /* Use legacy mode in IRTE */ > @@ -898,7 +905,7 @@ int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq, > * was cached. If so, we need to clean up the per-vcpu > * ir_list. > */ > - if (!ret && pi.prev_ga_tag) { > + if (!ret && pi.prev_ga_tag && !WARN_ON(!pi.ir_data)) { > int id = AVIC_GATAG_TO_VCPUID(pi.prev_ga_tag); > struct kvm_vcpu *vcpu; > > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu