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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 1AB75D116F1 for ; Mon, 1 Dec 2025 15:03:11 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vQ5Q0-0005tg-6m; Mon, 01 Dec 2025 10:02:24 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vQ5Pu-0005t4-7b for qemu-devel@nongnu.org; Mon, 01 Dec 2025 10:02:18 -0500 Received: from fra-out-008.esa.eu-central-1.outbound.mail-perimeter.amazon.com ([35.158.23.94]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vQ5Ps-0007AK-L5 for qemu-devel@nongnu.org; Mon, 01 Dec 2025 10:02:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.es; i=@amazon.es; q=dns/txt; s=amazoncorp2; t=1764601336; x=1796137336; h=message-id:from:to:cc:date:in-reply-to:references: content-transfer-encoding:mime-version:subject; bh=G2Z6L/cGrX6dkkxT/efBGobLCUv8I8U4zeLwHCLNZ6E=; b=EvHaAOCOrFiuJG8dOP4Zqv/tYzIlYZV4zGbzsI6Eb54IwMQXCKQHh+tT /TRA28pIhKp+5ojXgGJgqTQBmG2gQkrxFCyvxBnNh6WC13XD0sUbm8HU5 9AxGNWGLV98I3CVlRrGei5bMs9a3Hn6L/XBUtRWGz/AOZHsQIExzRMo6e crajbj1koY8Mq6xH70P2TpJTsCX/jww1OjkaP+lQ2tmZnk1vtrNAjrGCx HxcIM1TtIw38D3BM/rbOehdU1iBOgnmShasDSs9UER52yKC7/VQlAZjyz Dl9ZGoGaj9n/9Xa0cetpBPuJoE2PaipuRfaD2qxbyzpGI8uVEzVSPsTx5 g==; X-CSE-ConnectionGUID: lzdX0k8bSS6n99PeigtYxA== X-CSE-MsgGUID: EYZvUwXNQqOzOQOeraz9/A== X-IronPort-AV: E=Sophos;i="6.20,241,1758585600"; d="scan'208";a="6066050" Subject: Re: [RFC PATCH 3/4] hw/acpi: add VM generation counter field to VMClock Received: from ip-10-6-6-97.eu-central-1.compute.internal (HELO smtpout.naws.eu-central-1.prod.farcaster.email.amazon.dev) ([10.6.6.97]) by internal-fra-out-008.esa.eu-central-1.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Dec 2025 15:01:58 +0000 Received: from EX19MTAEUB002.ant.amazon.com [54.240.197.232:18877] by smtpin.naws.eu-central-1.prod.farcaster.email.amazon.dev [10.0.31.35:2525] with esmtp (Farcaster) id cfbf6f4a-9006-4153-86da-d61aad585e20; Mon, 1 Dec 2025 15:01:57 +0000 (UTC) X-Farcaster-Flow-ID: cfbf6f4a-9006-4153-86da-d61aad585e20 Received: from EX19D012EUA001.ant.amazon.com (10.252.50.122) by EX19MTAEUB002.ant.amazon.com (10.252.51.59) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.29; Mon, 1 Dec 2025 15:01:57 +0000 Received: from [127.0.0.1] (10.13.181.70) by EX19D012EUA001.ant.amazon.com (10.252.50.122) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.29; Mon, 1 Dec 2025 15:01:53 +0000 Message-ID: <843dc13c2dbb2b1f0bd622fe90e388e3e0752b92.camel@amazon.es> From: Babis Chalios To: "Daniel P. =?ISO-8859-1?Q?Berrang=E9?=" , "David Woodhouse" CC: "mst@redhat.com" , "imammedo@redhat.com" , "cohuck@redhat.com" , "pbonzini@redhat.com" , "qemu-devel@nongnu.org" , "Graf (AWS), Alexander" , "mzxreary@0pointer.de" Date: Mon, 1 Dec 2025 16:01:49 +0100 In-Reply-To: References: <20251201125023.18344-1-bchalios@amazon.es> <20251201125023.18344-5-bchalios@amazon.es> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.4-0ubuntu2 MIME-Version: 1.0 X-Originating-IP: [10.13.181.70] X-ClientProxiedBy: EX19D045UWA001.ant.amazon.com (10.13.139.83) To EX19D012EUA001.ant.amazon.com (10.252.50.122) Received-SPF: pass client-ip=35.158.23.94; envelope-from=prvs=423f6341f=bchalios@amazon.es; helo=fra-out-008.esa.eu-central-1.outbound.mail-perimeter.amazon.com 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_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, T_SPF_PERMERROR=0.01, UNPARSEABLE_RELAY=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, 2025-12-01 at 14:41 +0000, Daniel P. Berrang=C3=A9 wrote: > On Mon, Dec 01, 2025 at 02:29:57PM +0000, David Woodhouse wrote: > > On Mon, 2025-12-01 at 14:12 +0000, Daniel P. Berrang=C3=A9 wrote: > > > From QEMU's POV, live migration and snapshots > > > are indistiguishable operations, both using the same > > > functionaility. > > >=20 > > > eg > > > =C2=A0 $ qemu-system-x86_64 -monitor stdio -device vmclock > > > =C2=A0 (qemu) migrate file:snapshot.img > > >=20 > > > and > > >=20 > > > =C2=A0 $ qemu-system-x86_64 -monitor stdio -device vmclock -incoming > > > file:snapshot.img > > >=20 > > >=20 > > > and we can't check the QEMU migration target being "file:" and > > > mgmt > > > apps can use the "fd:" protocol to pass in a pre-opened target > > > which can > > > be a socket or pipe or file. > >=20 > > What triggers the vmgenid to actually get updated for a snapshot? > > That's the condition we're after, isn't it? >=20 > I don't quiet understand the sequences, but libvirt is involved in > setting > guid=3Dnnnn as an arg to -device vmgenid when it spawns QEMU. This > means > libvirt has control over when it is changed or not. >=20 That's a shame :( Maybe we could do the same as VMGenID then. Make vm_generation_counter something that the user can set when creating the device (same as VMGenID's GUID). WDYT David? Cheers, Babis