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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 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 AA815C2D0A3 for ; Mon, 26 Oct 2020 06:40:40 +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 0052022247 for ; Mon, 26 Oct 2020 06:40:39 +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="LqzhyBMJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0052022247 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]:42888 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kWwBL-0000rl-1D for qemu-devel@archiver.kernel.org; Mon, 26 Oct 2020 02:40:39 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54638) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kWw9z-0000Fa-Jg for qemu-devel@nongnu.org; Mon, 26 Oct 2020 02:39:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46576) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kWw9u-00058A-V5 for qemu-devel@nongnu.org; Mon, 26 Oct 2020 02:39:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603694349; 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: in-reply-to:in-reply-to:references:references; bh=6zHz96WNFkifywiq6D57QNzvgzD89m27/d1O1VEDojY=; b=LqzhyBMJmI9Y2HvWn5ztOuTQG+LXv3JqL1nu2PdXOat7R4qLX1AwevsKRHiU8VbQOydoyn T1gG+N49nDF8VKjIR346eIbkR+TWgvcIp7j/HSV8yo33Fi77uIxy6UzYEyBbTakv/oK8dA f0LSc13a4POrvWByY+BmpZ2UQq3/wxw= Received: from mail-pf1-f200.google.com (mail-pf1-f200.google.com [209.85.210.200]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-131-P3ko9pUdMzilnk7kNopKSQ-1; Mon, 26 Oct 2020 02:39:07 -0400 X-MC-Unique: P3ko9pUdMzilnk7kNopKSQ-1 Received: by mail-pf1-f200.google.com with SMTP id 203so2059429pfx.10 for ; Sun, 25 Oct 2020 23:39:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version; bh=6zHz96WNFkifywiq6D57QNzvgzD89m27/d1O1VEDojY=; b=M4mUhHXswww0y3ZKa1q7sWqKhnLZF3WPmqhXRT63W8ePpeGEv88htXE61sKZNvsfU7 SLoXZzvfTBiqVNjqoBuoQZDXKfMd/jIJqGeEH5/ZVPyFfLYDMeN/ruhG6s9Lomm02EzD pYLzqihG/YxE059AFB4p6klul9H3ld7SOu3osFL4Ap1Ajn/emkg4ll6ST1FxMqrDbmvU CgHAT38C+iXcsfhbZ1edJOtco6i7V0M0ln44Rd/hhSfkPLs1uVyCAjxwrwRgRF9c4IOt NGorq8hykFhEwBsMt4ELtkVXkpOkPJTKtRAFSfERyyT5tq7QUqDQMpsH8p10Akie4cVS hNFw== X-Gm-Message-State: AOAM531h5vzDzpwvghleM+49xR2mDH8nTtH9NNPHle/Ah5R9sBUhRDc9 iJfzAOqJ7SUhXcc0UaBY+sU3tyjD3jy2bss2Z5V5vzBX68aMpKQDWANwhIb/np6KpvIHDjB8ITR nK5rk/gbMRs2hPHM= X-Received: by 2002:a63:9a41:: with SMTP id e1mr12222644pgo.371.1603694346049; Sun, 25 Oct 2020 23:39:06 -0700 (PDT) X-Google-Smtp-Source: ABdhPJw/ES6CLPeKWUWZ+ZCHgMyMrbTFjt3jBiDhSYQn0qCz9OV/xm1Wj6w2dyrlYrQQF+SEyudKkQ== X-Received: by 2002:a63:9a41:: with SMTP id e1mr12222631pgo.371.1603694345762; Sun, 25 Oct 2020 23:39:05 -0700 (PDT) Received: from yekko.fritz.box ([2001:4479:e200:1100:3c24:4d96:ea81:be55]) by smtp.gmail.com with ESMTPSA id b20sm10459547pft.55.2020.10.25.23.39.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Oct 2020 23:39:05 -0700 (PDT) Date: Mon, 26 Oct 2020 17:38:57 +1100 From: David Gibson To: Igor Mammedov Subject: Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready Message-ID: <20201026173857.414878fb@yekko.fritz.box> In-Reply-To: <20201023192755.1845b060@redhat.com> References: <20201022080354-mutt-send-email-mst@kernel.org> <20201022235632.7f69ddc9@yekko.fritz.box> <20201022100028-mutt-send-email-mst@kernel.org> <20201022102857-mutt-send-email-mst@kernel.org> <20201022110016-mutt-send-email-mst@kernel.org> <20201023144901.5bd908a1@yekko.fritz.box> <20201023115029-mutt-send-email-mst@kernel.org> <20201023192755.1845b060@redhat.com> X-Mailer: Claws Mail 3.17.7 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgibson@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; boundary="Sig_/DMid0c9XUYQHHdsPQ_bsUnR"; protocol="application/pgp-signature"; micalg=pgp-sha256 Received-SPF: pass client-ip=216.205.24.124; envelope-from=dgibson@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/26 02:39:09 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H4=-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: Libvirt Mailing List , Julia Suvorova , qemu devel list , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --Sig_/DMid0c9XUYQHHdsPQ_bsUnR Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Fri, 23 Oct 2020 19:27:55 +0200 Igor Mammedov wrote: > On Fri, 23 Oct 2020 11:54:40 -0400 > "Michael S. Tsirkin" wrote: >=20 > [...] =20 > [...] =20 > [...] =20 > [...] =20 > >=20 > > Rather than adding_device_allowed, something like "query slot" > > might be helpful for debugging. That would help user figure out > > e.g. why isn't device visible without any races. =20 >=20 > Would be new command useful tough? What we end up is broken guest > (if I read commit message right) and a user who has no idea if=20 > device_add was successful or not. > So what user should do in this case > - wait till it explodes? > - can user remove it or it would be stuck there forever? > - poll slot before hotplug, manually? >=20 > (if this is the case then failing device_add cleanly doesn't sound bad, > it looks similar to another error we have "/* Check if hot-plug is disabl= ed on the slot */" > in pcie_cap_slot_pre_plug_cb) >=20 > CCing libvirt, as it concerns not only QEMU. >=20 > [...] =20 > [...] =20 > >=20 > > I think we want QEMU management interface to be reasonably > > abstract and agnostic if possible. Pushing knowledge of hardware > > detail to management will just lead to pain IMHO. > > We supported device_add which practically never fails for years, =20 >=20 > For CPUs and RAM, device_add can fail so maybe management is also > prepared to handle errors on PCI hotplug path. There can be unarguable reasons for PCI hotplug to fail as well (attempting to plug to a bus that can't support it for one). The difference here is that it's a failure that we expect to be transitory. --=20 David Gibson Principal Software Engineer, Virtualization, Red Hat --Sig_/DMid0c9XUYQHHdsPQ_bsUnR Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAl+WbwEACgkQbDjKyiDZ s5L0/BAA1nt3jQRIK/RTUUAOKvQp/WJLu+lf+8qqGrrqJcZ26wLHIW0TwbwTYcEp 6kDF8yxMBQ9eSAULw4f12QebhynYieQb4FnHakmUW65neLBFu0fFwK9AIBEayCMx YPvL5lFxsXi5TSWARfvSKvNkETh0tSWnzNbzKJXPZvnaP2P712sXcFawbGGm7+bi dlT19tvTYNkYi61V0HH8POmrv2J15tYkTon/H4G3Q8RnCA8ZemNbRX9U7myHxTkE W4JbZUA7Ouc7AoQH9YrD9hyGHJuXxfbS+YIRsm3fuuqNNAhkDR8+v4YKbhR8rQVj c13zIfTprx09Uas2x4bROQtu03PyHQBvGK+43BRzBkxXYx3lDVdxQi74mrPxIfAz 7AK//NcEfHhReAzfCMWd0shmNiXmNVsVbtTD2LucfeX/zPLH/vr41J67G1qeAbYd 1Ye58cZFl3HJqp9ouXgJpHsvn4XAzTcW/nWx4NoLWjJmV99km3MQb5sNX3sFNkTX e+ZIUsOEgL6YI8v2bRMK1urrJRyvL1pmqZy3mvoYMV6qhZ/SanSVTkug87yuzOZD LdyXppGYdVcvlixZtJcxw9ANZhHw/LUGQ8CKsV4XPh2hEeaLf3XNWkCTaETOsij3 Dos8w/RYV8w4KuRY4ky97UELKPK1V2xlRKvWMtIB36m8J21M3mw= =TeJt -----END PGP SIGNATURE----- --Sig_/DMid0c9XUYQHHdsPQ_bsUnR--