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 lists1p.gnu.org (lists1p.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 05514C98302 for ; Tue, 22 Sep 2026 19:02:16 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x95kX-0002zK-CF; Tue, 22 Sep 2026 15:01:54 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x95kF-0002yq-8e for qemu-devel@nongnu.org; Tue, 22 Sep 2026 15:01:35 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x95kD-00005d-9m for qemu-devel@nongnu.org; Tue, 22 Sep 2026 15:01:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1790103692; 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=25R/+DYYe9NVTz/221RNUqL0O9Z26fVitLzix/o2JNc=; b=I06hAOfZgtvRjXViMddmTRzIjXAkDUp7Ja6cBRcCvCU2LDWn9TH3yhCmJkaGAAXyBmk3Ev LRQvTVXNyO/Dv4k4DkkP7DMEA7rT8zKoI/Zl2tgxC3aPTUh5qlbINz9pcCvAAn7vrpwULL KM8W4/WAIP6t/Odclh4XTiirrC1waXo= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-148-uRD_KmgtPvayLor-LnTeHA-1; Tue, 22 Sep 2026 15:01:27 -0400 X-MC-Unique: uRD_KmgtPvayLor-LnTeHA-1 X-Mimecast-MFC-AGG-ID: uRD_KmgtPvayLor-LnTeHA_1790103686 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CAE391956061; Tue, 22 Sep 2026 19:01:25 +0000 (UTC) Received: from localhost (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id E7C981956041; Tue, 22 Sep 2026 19:01:24 +0000 (UTC) Date: Tue, 22 Sep 2026 15:01:23 -0400 From: Stefan Hajnoczi To: Niklas Cassel Cc: Kevin Wolf , John Snow , "Denis V. Lunev" , Hanna Reitz , "Michael S. Tsirkin" , Sam Li , Damien Le Moal , qemu-block@nongnu.org, qemu-devel@nongnu.org Subject: Re: [PATCH v6 07/15] hw/block: reject a zoned device that the block sizes cannot address Message-ID: <20260922190123.GC340123@fedora> References: <20260921142819.2916043-1-cassel@kernel.org> <20260921142819.2916043-8-cassel@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="N3WZIE0VQil76Fud" Content-Disposition: inline In-Reply-To: <20260921142819.2916043-8-cassel@kernel.org> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, 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: 2.1.29 Precedence: list List-Id: qemu development 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 --N3WZIE0VQil76Fud Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Sep 21, 2026 at 04:28:09PM +0200, Niklas Cassel wrote: > The write granularity that a frontend reports is derived from the logical > and the physical block size, which are properties of the device model, > while the granularity that the medium requires and the write pointers > that it holds belong to the backend. Nothing ties them together, and > where they disagree a guest is told about a device it cannot use. >=20 > A backend can require a coarser granularity than the block sizes express. > A 512e host managed disk has a logical block size of 512 and requires > writes to a sequential zone to be a multiple of 4096, so attaching it > with a finer physical block size reports a granularity that the disk will > not accept, and the guest is given a plain I/O error for a request that > it was told was valid. >=20 > The write pointers can disagree in the same way. They outlive any > particular use of the device, while the block sizes are chosen afresh > every time it is attached, so a zone written with logical_block_size=3D512 > leaves a write pointer that logical_block_size=3D4096 cannot address. A > zone report expresses it in 512 byte sectors, so the guest is told about > a position that does not fall on a logical block boundary, which it can > neither read nor write, and the zone can then only be recovered by > resetting it. The reverse is harmless: a pointer laid down with a larger > logical block size is still a multiple of a smaller one. >=20 > Check both at realize time, along with the zone size and the zone > capacity, and refuse to start otherwise. The write pointers are already > held in memory by the driver, so this costs no I/O. >=20 > The check uses blkconf_zone_write_granularity(), the same value that a > frontend reports to its guest and validates requests against, so the > three cannot disagree. >=20 > Signed-off-by: Niklas Cassel > --- > hw/block/block.c | 63 ++++++++++++++++++++++++++++++++++++++++ > hw/block/virtio-blk.c | 4 +++ > include/hw/block/block.h | 1 + > 3 files changed, 68 insertions(+) Reviewed-by: Stefan Hajnoczi --N3WZIE0VQil76Fud Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQEzBAEBCgAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmqy0IMACgkQnKSrs4Gr c8gEygf/UFVky70vY5U7+W7sZDaQ8Z9750eEJi7o9tz6F5DC8yxGK7WqLlCQQdSF 9wpxPsYZimaFA04odIQmV0NCKi3MUALRe/tadh/JOOM3gQUT2Xu09KPrZ35abtnK cXw0B0C01sOnT9lcj5REywaQkgdDKyvXwwqrb2NxddZ0Y4NveVvGzmXqj7AyHkRM KGZYuwACjuvHbkneqD23Q8Cu/eRFWunTWE2IB7WT/H3bDriRHhwQC26mxjvt3EJI PzJli4s5ccaRBw7esGCyM6l/PKJe9eP7pceYsbWvlQfjPrYR+J/c/vdMTF/gpl0K avohLMVSzYaoXVtrT7/2yCd9p2MoFw== =J8YB -----END PGP SIGNATURE----- --N3WZIE0VQil76Fud--