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a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734011114; 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: in-reply-to:in-reply-to:references:references; bh=FgrIAgtzIrtHJdpkYfPPWSVKe6gR+OdzkpR3IyZST3E=; b=eMsKf6oGhaoxDQzsb20+ETr1kF0pamywjOwK+Q3hNGowK44uYQLZu0MKDUMMB3yCUdKZ72 lpAVRnkKeL5bBBWnR258J3KKPsar+smASXK6hYnkooZN2ErKZF91yOuLhMJW/3KOch3IQo Kz4KPv85X8da1gQJuY+bw6EllDF/CUw= X-MC-Unique: 4CHZiw8WP8Kzxhj8lfT8zg-1 X-Mimecast-MFC-AGG-ID: 4CHZiw8WP8Kzxhj8lfT8zg From: Vitaly Kuznetsov <vkuznets@redhat.com> To: qemu-devel@nongnu.org, Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>, qemu-block@nongnu.org Cc: Eric Blake <eblake@redhat.com>, Philippe Mathieu-Daude <philmd@linaro.org> Subject: [PATCH v4 1/2] vpc: Split off vpc_ignore_current_size() helper Date: Thu, 12 Dec 2024 14:45:03 +0100 Message-ID: <20241212134504.1983757-2-vkuznets@redhat.com> In-Reply-To: <20241212134504.1983757-1-vkuznets@redhat.com> References: <20241212134504.1983757-1-vkuznets@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" In preparation to making changes to the logic deciding whether CHS or 'current_size' need to be used in determining the image size, split off vpc_ignore_current_size() helper. No functional change intended. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Philippe Mathieu-Daud=C3=A9 <philmd@linaro.org> --- block/vpc.c | 67 +++++++++++++++++++++++++++++------------------------ 1 file changed, 37 insertions(+), 30 deletions(-) diff --git a/block/vpc.c b/block/vpc.c index d95a204612b7..fb0ded1c4344 100644 --- a/block/vpc.c +++ b/block/vpc.c @@ -216,6 +216,41 @@ static void vpc_parse_options(BlockDriverState *bs, Qe= muOpts *opts, } } =20 +/* + * 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. + */ +static bool vpc_ignore_current_size(VHDFooter *footer) +{ + return !!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)); +} + static int vpc_open(BlockDriverState *bs, QDict *options, int flags, Error **errp) { @@ -304,36 +339,8 @@ static int vpc_open(BlockDriverState *bs, QDict *optio= ns, int flags, bs->total_sectors =3D (int64_t) be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl; =20 - /* 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 meth= od: - * 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. Otherwis= e, - * 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 =3D (!!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_ch= s; + /* Use CHS or current_size to determine the image size. */ + use_chs =3D vpc_ignore_current_size(footer) || s->force_use_chs; =20 if (!use_chs || bs->total_sectors =3D=3D VHD_MAX_GEOMETRY || s->force_= use_sz) { bs->total_sectors =3D be64_to_cpu(footer->current_size) / --=20 2.47.0 From nobody Sat May 10 20:55:32 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; 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a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734011121; 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: in-reply-to:in-reply-to:references:references; bh=81cVUqQuOeY7z2nPcKsGnCBnf66r+iuJcrd9VyY4oB4=; b=EtmDYhW0Y7oUSMJFVrm2cB6lYW1ci7cJadgxJjh7k+OyzQhIjRHUNbsWLGFes9PUNzwyA0 cb+TY6DgxFE7f0Ws/7VfC7+THaV3xyCLL6yYeHawhEPDQPF9AUEX1ye62lbWvKi4HZOScc iaoURoqPEmHQ+eOoozhARE2btpSKXPM= X-MC-Unique: bKXjqWweP0W4JssFiaa84A-1 X-Mimecast-MFC-AGG-ID: bKXjqWweP0W4JssFiaa84A From: Vitaly Kuznetsov <vkuznets@redhat.com> To: qemu-devel@nongnu.org, Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>, qemu-block@nongnu.org Cc: Eric Blake <eblake@redhat.com>, Philippe Mathieu-Daude <philmd@linaro.org> Subject: [PATCH v4 2/2] vpc: Read images exported from Azure correctly Date: Thu, 12 Dec 2024 14:45:04 +0100 Message-ID: <20241212134504.1983757-3-vkuznets@redhat.com> In-Reply-To: <20241212134504.1983757-1-vkuznets@redhat.com> References: <20241212134504.1983757-1-vkuznets@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" 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 <vkuznets@redhat.com> --- block/vpc.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/block/vpc.c b/block/vpc.c index fb0ded1c4344..a5f626baf04a 100644 --- a/block/vpc.c +++ b/block/vpc.c @@ -237,6 +237,7 @@ static void vpc_parse_options(BlockDriverState *bs, Qem= uOpts *opts, * '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 @@ -244,11 +245,8 @@ static void vpc_parse_options(BlockDriverState *bs, Qe= muOpts *opts, */ static bool vpc_ignore_current_size(VHDFooter *footer) { - return !!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)); + return !strncmp(footer->creator_app, "vpc ", 4) || + !strncmp(footer->creator_app, "qemu", 4); } =20 static int vpc_open(BlockDriverState *bs, QDict *options, int flags, --=20 2.47.0