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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 2C392C433E1 for ; Wed, 22 Jul 2020 16:19:37 +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 E8D0A20771 for ; Wed, 22 Jul 2020 16:19:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Tb3U5v63" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E8D0A20771 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]:49184 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jyHSy-0005nU-7R for qemu-devel@archiver.kernel.org; Wed, 22 Jul 2020 12:19:36 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33842) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jyHR1-0003hz-2s for qemu-devel@nongnu.org; Wed, 22 Jul 2020 12:17:35 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:26419 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jyHQy-00044T-IO for qemu-devel@nongnu.org; Wed, 22 Jul 2020 12:17:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595434650; 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; bh=6MLqu9HsFjL05pldt1yhj0jp24i4tPcl9tEGZ0+OWiM=; b=Tb3U5v63ghX4Fp6SArc+zRQ6N0EMxpzD6gjzagJgZTh2RfLzlMQ1e4w46jZ2AxY+USVAp5 Y+eL0iBvp9LQ35VF3u2e04aJfZyK7rHOAbiLI0jSTOqQ4wITbbIuoPxIkanUt53wilQj3U Hx59rBk61T7CD5098PL9bmXqoK+gYtc= 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-37-caDdXhmdPLOLJOATltBzaA-1; Wed, 22 Jul 2020 12:17:28 -0400 X-MC-Unique: caDdXhmdPLOLJOATltBzaA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6CDFB8005B0; Wed, 22 Jul 2020 16:17:27 +0000 (UTC) Received: from starship.redhat.com (unknown [10.35.206.82]) by smtp.corp.redhat.com (Postfix) with ESMTP id 57BD474F58; Wed, 22 Jul 2020 16:17:23 +0000 (UTC) From: Maxim Levitsky To: qemu-devel@nongnu.org Subject: [PATCH 0/1] RFC: pcie: parital fix for missing unplug events Date: Wed, 22 Jul 2020 19:17:21 +0300 Message-Id: <20200722161722.51416-1-mlevitsk@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mlevitsk@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=207.211.31.81; envelope-from=mlevitsk@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/21 23:34:34 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Maxim Levitsky , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" As described in bugzilla #1854264 it is possible to plug=0D a pcie device and then unplug it before the guest notices=0D (has time to process the attention button press)=0D =0D To partially fix this issue, detect and refuse the hotunplug event.=0D =0D There are other ways to fix this, which is why I am sending this as RFC:=0D =0D 1. Queue/remember the unplug event and fire it (press the attention button = again),=0D when the guest clears its pending status.=0D According to the spec this should cancel the hotplug event in the guest=0D if done within 5 seconds (and I think that guest actually should wait 5 sec= onds=0D after attention button is pressed before plugging in the device too to be s= trictly=0D up to the spec)=0D =0D 2. Detect that device isn't yet powered on by the guest (for example=0D checking the bus master bit) or check that attention button is still=0D pressed and in this case just unplug the device immediately.=0D =0D Best regards,=0D =09Maxim Levitsky=0D =0D Maxim Levitsky (1):=0D pci/pcie: refuse another hotplug/unplug event if attention button is=0D pending=0D =0D hw/pci/pcie.c | 11 +++++++++++=0D 1 file changed, 11 insertions(+)=0D =0D --=20=0D 2.26.2=0D =0D