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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 2C2A6C43331 for ; Thu, 26 Mar 2020 13:41:21 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 EAB4D2076A for ; Thu, 26 Mar 2020 13:41:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cj8WK38s" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EAB4D2076A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:51926 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jHSl6-0003SN-2W for qemu-devel@archiver.kernel.org; Thu, 26 Mar 2020 09:41:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57529) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jHSkA-0002Gz-74 for qemu-devel@nongnu.org; Thu, 26 Mar 2020 09:40:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jHSk8-0001Hk-Kr for qemu-devel@nongnu.org; Thu, 26 Mar 2020 09:40:21 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:45324) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jHSk8-0001HN-CJ for qemu-devel@nongnu.org; Thu, 26 Mar 2020 09:40:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585230019; 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=rCYr0d62dAcG/vbDx3bXeo52O/ssg+gGu8HNGqy9AU4=; b=cj8WK38sLamqmGsyXEjyTmzw+TKvQvbu3KwJpyjHtOFmrLcKf01IbxiewEDQ4+3CqtMCE2 bJuvws8DWYrg74S4xZacnd1hMYqLg01Mtm7fWlsIirXi1NmJ6HuxFcnRwizTtd7x7nwKOp 92772yztiYjYLWFECiuT6q18eIIrvpo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-165-Zgm424a2NKysYI2MnWVQcw-1; Thu, 26 Mar 2020 09:40:18 -0400 X-MC-Unique: Zgm424a2NKysYI2MnWVQcw-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 062F1107B796; Thu, 26 Mar 2020 13:40:17 +0000 (UTC) Received: from localhost (unknown [10.40.208.76]) by smtp.corp.redhat.com (Postfix) with ESMTP id A556D5C1B0; Thu, 26 Mar 2020 13:40:10 +0000 (UTC) Date: Thu, 26 Mar 2020 14:40:08 +0100 From: Igor Mammedov To: "Michael S. Tsirkin" Subject: Re: acpi_pcihp_eject_slot() bug if passed 'slots == 0' Message-ID: <20200326144008.7511cdf5@redhat.com> In-Reply-To: <20200326092955-mutt-send-email-mst@kernel.org> References: <20200326142317.018c13e1@redhat.com> <20200326092535-mutt-send-email-mst@kernel.org> <20200326092955-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 216.205.24.74 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 26 Mar 2020 09:31:09 -0400 "Michael S. Tsirkin" wrote: > On Thu, Mar 26, 2020 at 09:28:27AM -0400, Michael S. Tsirkin wrote: > > On Thu, Mar 26, 2020 at 02:23:17PM +0100, Igor Mammedov wrote: > > > On Thu, 26 Mar 2020 11:52:36 +0000 > > > Peter Maydell wrote: > > > > > > > Hi; Coverity spots that if hw/acpi/pcihp.c:acpi_pcihp_eject_slot() > > > > is passed a zero 'slots' argument then ctz32(slots) will return 32, > > > > and then the code that does '1U << slot' is C undefined behaviour > > > > because it's an oversized shift. (This is CID 1421896.) > > > > > > > > Since the pci_write() function in this file can call > > > > acpi_pcihp_eject_slot() with an arbitrary value from the guest, > > > > I think we need to handle 'slots == 0' safely. But what should > > > > the behaviour be? > > > > > > it also uncovers a bug, where we are not able to eject slot 0 on bridge, > > > > > > And that is by design. A standard PCI SHPC register can support up to 31 > > hotpluggable slots. So we chose slot 0 as non hotpluggable. > > It's consistent across SHPC, PCI-E, so I made ACPI match. > > Sorry I was confused. It's a PCI thing, PCI-E does not have > slot numbers for downstream ports at all. Scratch that, it was mistake on my part where I tests with a change that masks 0 and wrongly at that. slot 0 on bridge can be removed just fine > > > You can't hot-add it either. > > > > > can be reproduced with: > > > > > > -enable-kvm -m 4G -device pci-bridge,chassis_nr=1 -global PIIX4_PM.acpi-pci-hotplug-with-bridge-support=on -device virtio-net-pci,bus=pci.1,addr=0,id=netdev12 > > > > > > (monitor) device_del netdev12 > > > (monitor) qtree # still shows the device > > > > > > reason is that acpi_pcihp_eject_slot() > > > if (PCI_SLOT(dev->devfn) == slot) { # doesn't match (0 != 32) > > > > > > so device is not deleted > > > > We should probably teach QEMU that some slots aren't hotpluggable > > even if device in it is hotpluggable in theory. But that is > > a separate issue. > > > > > > thanks > > > > -- PMM > > > > >