From nobody Sun Oct 5 21:15:27 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1542248017360890.9507162299815; Wed, 14 Nov 2018 18:13:37 -0800 (PST) Received: from localhost ([::1]:35655 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gN7A0-0001rz-84 for importer@patchew.org; Wed, 14 Nov 2018 21:13:36 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53616) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gN70m-0002LG-S1 for qemu-devel@nongnu.org; Wed, 14 Nov 2018 21:04:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gN70l-0005h0-JF for qemu-devel@nongnu.org; Wed, 14 Nov 2018 21:04:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55002) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gN70e-0005dG-9f; Wed, 14 Nov 2018 21:03:58 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7FA4489ADB; Thu, 15 Nov 2018 02:03:54 +0000 (UTC) Received: from red.redhat.com (ovpn-123-32.rdu2.redhat.com [10.10.123.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id F1EE960BF6; Thu, 15 Nov 2018 02:03:50 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Date: Wed, 14 Nov 2018 20:03:26 -0600 Message-Id: <20181115020334.1189829-6-eblake@redhat.com> In-Reply-To: <20181115020334.1189829-1-eblake@redhat.com> References: <20181115020334.1189829-1-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Thu, 15 Nov 2018 02:03:54 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2 05/13] block: Switch to 64-bit bl.max_transfer X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, Fam Zheng , Stefan Hajnoczi , qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" This change has no semantic impact: all drivers either leave the value at 0 (no inherent 32-bit limit is still translated into fragmentation below 2G; see the previous patch for that audit), or set it to a value less than 2G. However, switching to a larger type and enforcing the 2G cap at the block layer makes it easier to audit specific drivers for their robustness to larger sizing, by letting them specify a value larger than INT_MAX if they have been audited to be 64-bit clean. Signed-off-by: Eric Blake --- include/block/block_int.h | 8 +++++--- block/io.c | 7 +++++++ 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/include/block/block_int.h b/include/block/block_int.h index f605622216d..b19d94dac5f 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -549,9 +549,11 @@ typedef struct BlockLimits { /* Maximal transfer length in bytes. Need not be power of 2, but * must be multiple of opt_transfer and bl.request_alignment, or 0 - * for no 32-bit limit. For now, anything larger than INT_MAX is - * clamped down. */ - uint32_t max_transfer; + * for no 32-bit limit. The block layer fragments all actions + * below 2G, so setting this value to anything larger than INT_MAX + * implies that the driver has been audited for 64-bit + * cleanness. */ + uint64_t max_transfer; /* memory alignment, in bytes so that no bounce buffer is needed */ size_t min_mem_alignment; diff --git a/block/io.c b/block/io.c index 39d4e7a3ae1..4911a1123eb 100644 --- a/block/io.c +++ b/block/io.c @@ -159,6 +159,13 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error *= *errp) if (drv->bdrv_refresh_limits) { drv->bdrv_refresh_limits(bs, errp); } + + /* Clamp max_transfer to 2G */ + if (bs->bl.max_transfer > UINT32_MAX) { + bs->bl.max_transfer =3D QEMU_ALIGN_DOWN(BDRV_REQUEST_MAX_BYTES, + MAX(bs->bl.opt_transfer, + bs->bl.request_alignment= )); + } } /** --=20 2.17.2