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 X-Spam-Level: X-Spam-Status: No, score=-12.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C987C2B9F4 for ; Tue, 22 Jun 2021 19:35:52 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 106036113E for ; Tue, 22 Jun 2021 19:35:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 106036113E Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=citrix.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.146067.268697 (Exim 4.92) (envelope-from ) id 1lvmBI-0005T8-BD; Tue, 22 Jun 2021 19:35:32 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 146067.268697; Tue, 22 Jun 2021 19:35:32 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lvmBI-0005T1-7Y; Tue, 22 Jun 2021 19:35:32 +0000 Received: by outflank-mailman (input) for mailman id 146067; Tue, 22 Jun 2021 19:35:31 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lvmBH-0005Sv-85 for xen-devel@lists.xenproject.org; Tue, 22 Jun 2021 19:35:31 +0000 Received: from esa6.hc3370-68.iphmx.com (unknown [216.71.155.175]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id bdaeebac-cc0c-4144-9ecd-3d2f657fa5cc; Tue, 22 Jun 2021 19:35:29 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: bdaeebac-cc0c-4144-9ecd-3d2f657fa5cc DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1624390528; h=to:cc:references:from:subject:message-id:date: in-reply-to:content-transfer-encoding:mime-version; bh=UxgAPpj3Bju409mglp5pUiFnbpcpj17y4j6EuXBk8ZY=; b=JR2KOG/bJWqC0I+rCixfl1XId5lNEWcm/wjBbTfQhRT80Hjk4qLW+n8U 0nQF/g85gU/9XMIzaopZMc8nw+16wVPjDlUAtm46NwI4psoq+Stx6KmxN lFPi49896RXKodMe375ic2oJsVinTkct1h6YbnfwMqnV+PSD9O7Zb8tVl Y=; Authentication-Results: esa6.hc3370-68.iphmx.com; dkim=pass (signature verified) header.i=@citrix.onmicrosoft.com IronPort-SDR: snSCV/BtX0JFjoKmblLr2umn3XiSiFDmCjovm2Hcv+gCgcWbhgdJjRuz+u76NEWq+LDEecnBI1 arFCyTuBHNDXbcRxZ+6Uu6LZho7dqgQhK3Y/OXX6atoiQID+WYv9COvV+2l5GhomKrg62EGnLH ofUyQ5fDogDg+kAzyYn7SD8k2FSBqal22BXWhJ06IxNJgElM16xlZIZt5H29m/F1FMJuna8cQF iqkfY0B+l6RQoHBMB+vdYam0FARL8ofC8ZYXYI8Jk61EzYwTrPEujWQFNwK9+jZzP56GHkVU/g 3ZE= X-SBRS: 5.1 X-MesageID: 46787766 X-Ironport-Server: esa6.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED IronPort-HdrOrdr: A9a23:LpnRLqiY9iI54JcxnInN8GdxRXBQXh4ji2hC6mlwRA09TyX5ra 2TdZUgpHrJYVMqMk3I9uruBEDtex3hHP1OkOss1NWZPDUO0VHARO1fBOPZqAEIcBeOldK1u5 0AT0B/YueAd2STj6zBkXSF+wBL+qj6zEiq792usEuEVWtRGsVdB58SMHfiLqVxLjM2YqYRJd 6nyedsgSGvQngTZtTTPAh/YwCSz+e78q4PeHQ9dmca1DU= X-IronPort-AV: E=Sophos;i="5.83,292,1616472000"; d="scan'208";a="46787766" ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=VRuDmQGGiwolNgS1tvThDaMYzM4IFz/J4uhkRR1tgfJ962O4FDnQH3LYww7PPh/R9tCxK2MYRuyUycqMEnWHm91ZL9HHaCnL4ZYZMHRZ6XxGl3RfguOGUjCml025ua4vzGK9BsWj9jxAeqnrJGU1tbPK/7oxVSdJQl4zabZArwadof+rp3g3Ri+ZuI+ER84LffIqzvXolKyCReePbyAWFmGRBtSlLp6e0Ccd54g1DliN9hEsCpCFOHP5PwyxafgaB6mbvQbm4Ut6GjjG8RtdxRie/txotOXwCh+WhvbPqqCTWNm9DbS/oXpYMzyuesngfIIzmVj15GRgjNp6mbP7iA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=UxgAPpj3Bju409mglp5pUiFnbpcpj17y4j6EuXBk8ZY=; b=JTRc/y6qnzTZ6p/KRfxXVYot6UQ9VjuwPpM06/zXjfz5e2w/bhCGp8+nNdQYyke3l4uXLMJTwuGiIWjYns1h02VcmBSt1+6wmz2O26QxRJ0XjbTRcUFIum1YJ+fuHXgdhd/09HyaV5lsNkpNuas/9e8LIhFcexdoH2GpFvZzcvXvlWLH3uAl8fRQRT7ZwIdxuZij/0bxZWET8VVn7pqBCQjSMpRJYa5c9MQhQWFkxUzJzgEKZL+0DVG4ReHSywQmpynHV9/2C32EuepKSWPUB9om0KJsdluIUNoUK7fk+zZKplBAjCMD4eRzAeow7FLdLVk+jc0lGffJn4VAnPC9GQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=citrix.com; dmarc=pass action=none header.from=citrix.com; dkim=pass header.d=citrix.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.onmicrosoft.com; s=selector2-citrix-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=UxgAPpj3Bju409mglp5pUiFnbpcpj17y4j6EuXBk8ZY=; b=vrNUiKzS6fJJuQY9rOmxgIAFWwYBRNvYwKewDihH/McaDTR7ZaDA7w2jCtXGa3jzI85dMXYDxhbIxLDFfdm4CVUDc9MB4vgspxvileS1fERRux5zFXEeD6+iAz+hWdb5XhpWDVvw1Z0ZajnUZUsyeWagXgdeYt9YSh+q+AOAqEU= To: Jan Beulich , "xen-devel@lists.xenproject.org" CC: Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Ian Jackson , Juergen Gross References: <6c532607-c2a3-d0ab-e4e5-428f85f4a045@suse.com> From: Andrew Cooper Subject: Re: [PATCH v2 4/6] libxc: use multicall for memory-op on Linux (and Solaris) Message-ID: <215dccb1-602b-20dd-2298-84ce11a797b7@citrix.com> Date: Tue, 22 Jun 2021 20:35:18 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-GB X-ClientProxiedBy: LO2P265CA0497.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:13a::22) To BYAPR03MB3623.namprd03.prod.outlook.com (2603:10b6:a02:aa::12) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 44ad89ca-4f6a-4612-75f6-08d935b4e1d4 X-MS-TrafficTypeDiagnostic: BYAPR03MB3670: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:8273; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR03MB3623.namprd03.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(376002)(136003)(396003)(346002)(366004)(39860400002)(5660300002)(86362001)(110136005)(316002)(31696002)(478600001)(54906003)(186003)(16526019)(53546011)(26005)(16576012)(2616005)(66556008)(66476007)(4326008)(956004)(2906002)(36756003)(66946007)(8936002)(38100700002)(31686004)(8676002)(6666004)(6486002)(45980500001)(43740500002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?UC9HMVdjanpWbFJxNFA5K3I3M0FZVS9pVWVZK3NGMDNqdDFxZk10VUtoQ2ZB?= =?utf-8?B?ekJKaDB1VzdUVXRCNW5vRG1uTE1JdmhlS29QVzM2dUdmQVBDTXpPOHhIWEVK?= =?utf-8?B?cFpDRTA2eDlBSWlXRmpmNzA4UUh1YjJURFdkd1lyaS9VcW5QdnJWbjdjUXpK?= =?utf-8?B?MXh6UmYzTDk4VnN5Um12ZzNOdnVqSXBqWk5KbTQ1eWJSVHZIZmF2QnJIWWZq?= =?utf-8?B?K2dRL0FCdFdGWUhDbDNZMkY0ZnFRMm02VW1uM1RpNXVXWWV0Unl2ZlkvT2xO?= =?utf-8?B?QyszZS9KWDVQbU5ocUxxb2dwQnI5U0ZpU2tRRTFPMldRb05vbjNudzFhSW80?= =?utf-8?B?ZmRBd04yZTZXY2N1cDE1cjFwTm5CSnhPNEdGMlNOSkxCRWtucFJ6ZTRXZkhM?= =?utf-8?B?QkVLZ25TOXB6Q3Nid1pNbWFVUUxMRDN3TUdKWjdCM2Q0NkNZdDc5NStxRHly?= =?utf-8?B?UXhTQWhsejVVZXBvR3NkZHExdjF1OXE0TFF6MVZmY2xEN2dlSDFMUzFwa2Iv?= =?utf-8?B?R1hMZ1dLa0VTQXREWWhVeU56SnV2MEpya2FCR2dXcjhWNG5Bc1BWYjBWT2VW?= =?utf-8?B?S0lTZm5vOWdvK0NaQzlmdDdrOTlQdHNHMXJOK1E3SnpQT1VuTFhRVmpieHRw?= =?utf-8?B?a3dkUXdLaHgybXdLVHJBUWtEUk43NmxnaFlwbE9qWTZRYkJVbU5WVHlwMEhK?= =?utf-8?B?bGRNMVk2ZjIvQW4rTzJJREtGd3R5dHl4M3lGWXNUVmI2aUtOdEh6ZjQ0MDgv?= =?utf-8?B?OVRHUWRCOXd2WG42ZzRxNkZkVlNOMjlvWlBjNDZpdjlYR0hDdWJSYmJlNE9L?= =?utf-8?B?cEJOeW9lNGRLVnJLNE9hYmNmeHpZekxSVXE3NTRUNHZOLzRaSGRteld4cHV6?= =?utf-8?B?N1R6OFBzWThWUWJaeW4xenI2U0syVmFDZXBIRU41WSs4RkNVem80RHh3cGU3?= =?utf-8?B?UkFvRGxQR24rQWJJVFk3MTZ5ODdaOFVrSlorV0d0RjVUYk9IRW5NTXFQeWhr?= =?utf-8?B?Q1JqN2ducnFyZmR3OVIvb25UQndHVG1jSmZFQ2lTemNKRCtIdVF4T0IwNndI?= =?utf-8?B?eFArQnMrS2diZjlKWjNpbkxKbTNKRFRYUlB4OHBxenRBSWlidElYcHhVUC9I?= =?utf-8?B?ZkJDVVk1M1hZSDlVaHlFS3lwOUI4REErV3N2Um9tbG1mSnc4dnBzWlBZYWVN?= =?utf-8?B?SFRzQlZ6S0tURDFkNWt6eGVHVzJ6MEU5Qy9leFNIK2ZIUFBSbkFjYnV0UUZG?= =?utf-8?B?UEx2TUdobG53SlFtRFlTZHdnOWtGc2RkK1p2dTVGTWhxOURHZDFXVUljLzlB?= =?utf-8?B?WEY1VC9uYUY4YkFHeWsrTHB1OFZxNXB0Q2Y1VElQYzdyZzc1ZUNRYVpqclQx?= =?utf-8?B?UnR4OXNiWHJERHVPMU5iT1NBd2NhRXJlZUVJeUxwMjJiWlZPTjhJRXp4ZTd0?= =?utf-8?B?MnhzM0hqUjVxRTRXbnpaRTlmcGlFNnk1cmVva2ozVk5hTktNSFo0N01NNW5T?= =?utf-8?B?MlFldkZmaElmU24rRHY3UVVrNysrak1vN0hrN083c3JQeGl0MlJrdzhrcGJU?= =?utf-8?B?QlhvRUl2SDMydUNTVm1reGU5RktFU0pEZ3NRSHNOd0xDVzhHeXlyMXdqNzIy?= =?utf-8?B?c3pxcWZYak55d213ZjNRL2NnRmYyVnV1ZjZXY2t1WWZGUndVekhqNUVTcUh6?= =?utf-8?B?WCtiSlE2MzVWenVnRVlCRGM3d0tBd2NaWk9tTmhGSitBVUhxSEhaV3FRV2oy?= =?utf-8?Q?A0dkqebPpj6jiwPOn6Lo/zdA6nny5mrXgAYRFEs?= X-MS-Exchange-CrossTenant-Network-Message-Id: 44ad89ca-4f6a-4612-75f6-08d935b4e1d4 X-MS-Exchange-CrossTenant-AuthSource: BYAPR03MB3623.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Jun 2021 19:35:25.1806 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 335836de-42ef-43a2-b145-348c2ee9ca5b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: c5mN59aBmZZpuCYtGnHLVAxGsC1Rm/UiyRFKS1l4CHxSUMTT7ND9+sNGhDHbg87DddLyM/Y6PnQhkSgvFCiN2sEiTwX1mYLIZ/IdNRc4Y+c= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR03MB3670 X-OriginatorOrg: citrix.com On 22/06/2021 16:19, Jan Beulich wrote: > Some sub-functions, XENMEM_maximum_gpfn and XENMEM_maximum_ram_page in > particular, can return values requiring more than 31 bits to represent. > Hence we cannot issue the hypercall directly when the return value of > ioctl() is used to propagate this value (note that this is not the case > for the BSDs, and MiniOS already wraps all hypercalls in a multicall). It took me 3 readings to realise you weren't saying that BSDs used multicall (which they don't). Instead, I'd suggest rewording it. "Some sub-functions, XENMEM_maximum_gpfn and XENMEM_maximum_ram_page in particular, can return values requiring more than 31 bits to represent. The BSDs deliberately avoid using the ioctl() return value, and MiniOS already uses a multicall.=C2=A0 They aren't affected. Linux and Solaris however do use the ioctl() return value, which must be avoided in this case to avoid truncation." Or something similar. With a suitable improvement along these lines, Acked-by: Andrew Cooper