From patchwork Thu Dec 12 12:25:12 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vitaly Kuznetsov X-Patchwork-Id: 13905138 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 6C3ADE77180 for ; Thu, 12 Dec 2024 12:26:09 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tLiG3-0002OB-Tt; Thu, 12 Dec 2024 07:25:31 -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 1tLiG0-0002NJ-Nx for qemu-devel@nongnu.org; Thu, 12 Dec 2024 07:25:30 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tLiFx-0002iA-D8 for qemu-devel@nongnu.org; Thu, 12 Dec 2024 07:25:28 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734006319; 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=AjGgD+MJ/PyoAb90y0Ao1Ic/UOIyMLqM/fFKOy4FyAQ=; b=ZFBJYV277+N+LwTtGMy7TNZhN9L56dbdYFQ12AiFLCVTkqmPTrIMfR+MX1nDyZy9w7Jv+h Lc50eJ0HDI/Q8hcToWkHFZF1+TcwIwOdd/aOAGLFT9bwWf7Ec4RTpe0z6oPgerBlG1KVmn 9Ne/6eV/1Ma3oiipmyz3MQPTGdS2gr4= 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-85-70eNxFPKO-CNJJSk4r1r_w-1; Thu, 12 Dec 2024 07:25:16 -0500 X-MC-Unique: 70eNxFPKO-CNJJSk4r1r_w-1 X-Mimecast-MFC-AGG-ID: 70eNxFPKO-CNJJSk4r1r_w Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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 850E21955F3E; Thu, 12 Dec 2024 12:25:15 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.45.225.198]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 895851956052; Thu, 12 Dec 2024 12:25:13 +0000 (UTC) From: Vitaly Kuznetsov To: qemu-devel@nongnu.org, Kevin Wolf , Hanna Reitz , qemu-block@nongnu.org Cc: Eric Blake Subject: [PATCH v3] vpc: Read images exported from Azure correctly Date: Thu, 12 Dec 2024 13:25:12 +0100 Message-ID: <20241212122512.1974242-1-vkuznets@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=vkuznets@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.496, 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_H2=-0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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 It was found that 'qemu-nbd' is not able to work with some disk images exported from Azure. Looking at the 512b footer (which contains VPC metadata): 00000000 63 6f 6e 65 63 74 69 78 00 00 00 02 00 01 00 00 |conectix........| 00000010 ff ff ff ff ff ff ff ff 2e c7 9b 96 77 61 00 00 |............wa..| 00000020 00 07 00 00 57 69 32 6b 00 00 00 01 40 00 00 00 |....Wi2k....@...| 00000030 00 00 00 01 40 00 00 00 28 a2 10 3f 00 00 00 02 |....@...(..?....| 00000040 ff ff e7 47 8c 54 df 94 bd 35 71 4c 94 5f e5 44 |...G.T...5qL._.D| 00000050 44 53 92 1a 00 00 00 00 00 00 00 00 00 00 00 00 |DS..............| 00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| we can see that Azure uses a different 'Creator application' -- 'wa\0\0' (offset 0x1c, likely reads as 'Windows Azure') and QEMU uses this field to determine how it can get image size. Apparently, Azure uses 'new' method, just like Hyper-V. Overall, it seems that only VPC and old QEMUs need to be ignored as all new creator apps seem to have reliable current_size. Invert the logic and make 'current_size' method the default to avoid adding every new creator app to the list. Signed-off-by: Vitaly Kuznetsov --- Changes since v1/v2: invert the logic and make 'vpc' and 'qemu' use CHS while defaulting to current_size. --- block/vpc.c | 65 ++++++++++++++++++++++++++++------------------------- 1 file changed, 35 insertions(+), 30 deletions(-) diff --git a/block/vpc.c b/block/vpc.c index d95a204612b7..e22d4bfe3fc1 100644 --- a/block/vpc.c +++ b/block/vpc.c @@ -216,6 +216,39 @@ static void vpc_parse_options(BlockDriverState *bs, QemuOpts *opts, } } +/* + * Microsoft Virtual PC and Microsoft Hyper-V produce and read + * VHD image sizes differently. VPC will rely on CHS geometry, + * while Hyper-V and disk2vhd use the size specified in the footer. + * + * We use a couple of approaches to try and determine the correct method: + * look at the Creator App field, and look for images that have CHS + * geometry that is the maximum value. + * + * If the CHS geometry is the maximum CHS geometry, then we assume that + * the size is the footer->current_size to avoid truncation. Otherwise, + * we follow the table based on footer->creator_app: + * + * Currently known creator apps: + * 'vpc ' : CHS Virtual PC (uses disk geometry) + * 'qemu' : CHS QEMU (uses disk geometry) + * 'qem2' : current_size QEMU (uses current_size) + * 'win ' : current_size Hyper-V + * 'd2v ' : current_size Disk2vhd + * 'tap\0' : current_size XenServer + * 'CTXS' : current_size XenConverter + * 'wa\0\0': current_size Azure + * + * The user can override the table values via drive options, however + * even with an override we will still use current_size for images + * that have CHS geometry of the maximum size. + */ +static bool vpc_ignore_current_size(VHDFooter *footer) +{ + return !strncmp(footer->creator_app, "vpc ", 4) || + !strncmp(footer->creator_app, "qemu", 4); +} + static int vpc_open(BlockDriverState *bs, QDict *options, int flags, Error **errp) { @@ -304,36 +337,8 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags, bs->total_sectors = (int64_t) be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl; - /* Microsoft Virtual PC and Microsoft Hyper-V produce and read - * VHD image sizes differently. VPC will rely on CHS geometry, - * while Hyper-V and disk2vhd use the size specified in the footer. - * - * We use a couple of approaches to try and determine the correct method: - * look at the Creator App field, and look for images that have CHS - * geometry that is the maximum value. - * - * If the CHS geometry is the maximum CHS geometry, then we assume that - * the size is the footer->current_size to avoid truncation. Otherwise, - * we follow the table based on footer->creator_app: - * - * Known creator apps: - * 'vpc ' : CHS Virtual PC (uses disk geometry) - * 'qemu' : CHS QEMU (uses disk geometry) - * 'qem2' : current_size QEMU (uses current_size) - * 'win ' : current_size Hyper-V - * 'd2v ' : current_size Disk2vhd - * 'tap\0' : current_size XenServer - * 'CTXS' : current_size XenConverter - * - * The user can override the table values via drive options, however - * even with an override we will still use current_size for images - * that have CHS geometry of the maximum size. - */ - use_chs = (!!strncmp(footer->creator_app, "win ", 4) && - !!strncmp(footer->creator_app, "qem2", 4) && - !!strncmp(footer->creator_app, "d2v ", 4) && - !!strncmp(footer->creator_app, "CTXS", 4) && - !!memcmp(footer->creator_app, "tap", 4)) || s->force_use_chs; + /* Use CHS or current_size to determine the image size */ + use_chs = vpc_ignore_current_size(footer) || s->force_use_chs; if (!use_chs || bs->total_sectors == VHD_MAX_GEOMETRY || s->force_use_sz) { bs->total_sectors = be64_to_cpu(footer->current_size) /