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=-3.6 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 CDCA9C433DB for ; Thu, 25 Mar 2021 01:53:31 +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 08BE8619E8 for ; Thu, 25 Mar 2021 01:53:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 08BE8619E8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:47104 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lPFBh-0002AB-Vh for qemu-devel@archiver.kernel.org; Wed, 24 Mar 2021 21:53:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52862) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lPFAp-00014Y-Oj; Wed, 24 Mar 2021 21:52:35 -0400 Received: from bilbo.ozlabs.org ([2401:3900:2:1::2]:50523 helo=ozlabs.org) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lPFAm-0007a7-S0; Wed, 24 Mar 2021 21:52:35 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 4F5Slt3Qf2z9sWX; Thu, 25 Mar 2021 12:52:26 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1616637146; bh=wqbuhJ6jHsElSix/fTSR2rOAX+XtGAGO1nJN4Fj/xUo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LewSEbf6ixLGHIZkeeMCf35r3U6EyG4kVTksZ+i1aivjbhho/Vhlxe/g7vXKfuf43 yQH15J7IQtPnQ9Pl2J4gC8xjg8vYb2yyiMUwTrH2EMDWRCwoRv9Q+BLhBFN2CghdHU zndU320sHvePfHhKeKF2+uIkNg+KGoJIZ9XcN/bg= Date: Thu, 25 Mar 2021 12:32:47 +1100 From: David Gibson To: Daniel Henrique Barboza Subject: Re: [PATCH 0/4] DEVICE_NOT_DELETED/DEVICE_UNPLUG_ERROR QAPI events Message-ID: References: <20210312200740.815014-1-danielhb413@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="qOOv7PlkpAyY/Pc7" Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=2401:3900:2:1::2; envelope-from=dgibson@ozlabs.org; helo=ozlabs.org X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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: armbru@redhat.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, groug@kaod.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --qOOv7PlkpAyY/Pc7 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Mar 24, 2021 at 04:09:59PM -0300, Daniel Henrique Barboza wrote: >=20 >=20 > On 3/23/21 10:40 PM, David Gibson wrote: > > On Tue, Mar 23, 2021 at 02:10:22PM -0300, Daniel Henrique Barboza wrote: > > >=20 > > >=20 > > > On 3/22/21 10:12 PM, David Gibson wrote: > > > > On Fri, Mar 12, 2021 at 05:07:36PM -0300, Daniel Henrique Barboza w= rote: > > > > > Hi, > > > > >=20 > > > > > This series adds 2 new QAPI events, DEVICE_NOT_DELETED and > > > > > DEVICE_UNPLUG_ERROR. They were (and are still being) discussed in= [1]. > > > > >=20 > > > > > Patches 1 and 3 are independent of the ppc patches and can be app= lied > > > > > separately. Patches 2 and 4 are based on David's ppc-for-6.0 bran= ch and > > > > > are dependent on the QAPI patches. > > > >=20 > > > > Implementation looks fine, but I think there's a bit more to discuss > > > > before we can apply. > > > >=20 > > > > I think it would make sense to re-order this and put UNPLUG_ERROR > > > > first. Its semantics are clearer, and I think there's a stronger c= ase > > > > for it. > > >=20 > > > Alright > > >=20 > > > >=20 > > > > I'm a bit less sold on DEVICE_NOT_DELETED, after consideration. Do= es > > > > it really tell the user/management anything useful beyond what > > > > receiving neither a DEVICE_DELETED nor a DEVICE_UNPLUG_ERROR does? > > >=20 > > >=20 > > > It informs that the hotunplug operation exceed the timeout that QEMU > > > internals considers adequate, but QEMU can't assert that it was caused > > > by an error or an unexpected delay. The end result is that the device > > > is not going to be deleted from QMP, so DEVICE_NOT_DELETED. > >=20 > > Is it, though? I mean, it is with this implementation for papr: > > because we clear the unplug_requested flag, even if the guest later > > tries to complete the unplug, it will fail. > >=20 > > But if I understand what Markus was saying correctly, that might not > > be possible for all hotplug systems. I believe Markus was suggesting > > that DEVICE_NOT_DELETED could just mean that we haven't deleted the > > device yet, but it could still happen later. > >=20 > > And in that case, I'm not yet sold on the value of a message that > > essentially just means "Ayup, still dunno what's happening, sorry". > >=20 > > > Perhaps we should just be straightforward and create a DEVICE_UNPLUG_= TIMEOUT > > > event. > >=20 > > Hm... what if we added a "reason" field to UNPLUG_ERROR. That could > > be "guest rejected hotplug", or something more specific, in the rare > > case that the guest has a way of signalling something more specific, > > or "timeout" - but the later *only* to be sent in cases where on the > > timeout we're able to block any later completion of the unplug (as we > > can on papr). >=20 > I believe that's already covered by the existing API: >=20 >=20 > +# @DEVICE_UNPLUG_ERROR: > +# > +# Emitted when a device hot unplug error occurs. > +# > +# @device: device name > +# > +# @msg: Informative message Oh, sorry, I missed that > The 'informative message' would be the reason the event occurred. In patch > 4/4, for the memory hotunplug refused by the guest, it is being set as: >=20 > qapi_error =3D g_strdup_printf("Memory hotunplug rejected by the gue= st " > "for device %s", dev->id); > qapi_event_send_device_unplug_error(dev->id, qapi_error); >=20 >=20 >=20 > We could use the same DEVICE_UNPLUG_ERROR event in the CPU hotunplug time= out > case (currently on patch 2/4) by just changing 'msg', e.g.: >=20 >=20 > qapi_error =3D g_strdup_printf("CPU hotunplug timeout for device %s"= , dev->id); > qapi_event_send_device_unplug_error(dev->id, qapi_error); I think that makes sense for the cases on papr. Less sure about the cases Markus has mentioned. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --qOOv7PlkpAyY/Pc7 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAmBb6DwACgkQbDjKyiDZ s5IimRAAmgdQk2S0HGsspow4QrrjjM1dC38Mv7nYwppbP6P26OYaWlePHUu3l4uJ q1t9dnpqqUC0FHYIg8/CsAj6ivjjyqwFJFovq7kPR/hIUIgvdfZ7IrbSOE2Zfkpq sQI73T/HJ8YRo0zMXSMgHqN760YMeNXB0LyltEXBRyIQw342ceJabS2wG/nsEhR3 DvDtTbVS8x2dJRSiBWYe3pd6r2yCKrTT10u7yN8agq5sQdAMkNUNhtgSI43TW42f 37QUtQdIrktMLVX2cr7Ejo6ziYwyxlYwXnzO8ssk0vlSHpCvL6nDyuYTdXZfqhOW t859aaF+D5yQOzHMFXC4sHsxj6VG+gYPqtoT+Hinu9BtUj+jXnIrpE8HGc8Lu8cy EAYKiTsPAGyTRYMP6RjRov8BEuxy9c7WjIbx9Z/WEvp+mXzks4PKEWYjt2wZY5P4 NfqIrGSnmnsiwqXooS5hDCtRKlVz2eRp5QcKKjvH4tbRJBtijAaZUNSqLoCbX4+/ WNjEMRIkQies+VJmJ7HBJjwwG1eklBF1pvSjBeL0gayHRtzStTeZQgLQWVn3m8tX hETrxGvIhstE8uAvEGUtDr4T2CsnDu51ueptv4gGC7CYX+P1nJhuNwHTok85+Qb5 vQAZQnEYizWIKnkDHuvzaNG2ZwPHv6W7I0c8jM07TdPDHPgJ41M= =IaKU -----END PGP SIGNATURE----- --qOOv7PlkpAyY/Pc7--