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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 480A1C43461 for ; Tue, 4 May 2021 08:15:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 225BA613B3 for ; Tue, 4 May 2021 08:15:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230111AbhEDIQi (ORCPT ); Tue, 4 May 2021 04:16:38 -0400 Received: from mail-eopbgr80107.outbound.protection.outlook.com ([40.107.8.107]:56259 "EHLO EUR04-VI1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S229848AbhEDIQh (ORCPT ); Tue, 4 May 2021 04:16:37 -0400 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=RQcdqptSyRCR2xpD0vMvdlpZpI25H40k0o2PETQgUpGYneU8nsvRQk+U2s8mgNl0DuIVfnAQ67lKTzv4mYEeLiOD5aNkcaF0wPQHg3i4us2cAgTN3uCL5/4jl3CtNIaDvP4ogqrTc8ibnwiV0wt0IjjiwjL0vJoGhfV9p/f+zvEGmDOcKS0m9YQ8fvkcdU5SLfW5GejMVnkCYR0O+FRzsiViEMUSVlQcho/5yRQGI6JkstGLH2dzZ7amJCxQ+cMjejLyXIvpYdPiDD1SjBWKLQM7S6vXZeyVKsW5M3nFAVzu9vUR7JVCWSF1OwIdVWBYg0dJvUXsgBxHxEkJDBxZsw== 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=9EPCyULGBca89daXLvU2x3D+5SJKQmqWm7yhdcd4uME=; b=UXiJ+Yrx84flrR8qe5zQq8DdN8gQbSV7oeEetgdikwXxCt1iZ60XNmv0gMvZk0STEgSRvYQfs9+FZ8FCRq2bdAM6X1FAAwhekmeXEdsEOjA2Ywa40CPqrFF1rLw28kW50B/ksIrfRy/EX4yOt5l50fLSfR7M77sotfgc3gl10zFMTMvhs0AmAYn4pj0NZv9Km1t6BC4sfiZD1bvGZH2gXhZ6vIhCLmq0hD9/VqUYTIDUrzERESBt4dw8wz8UjSw3/FKHZ9WAd2UWoqfC5MbpqO2AFMllTQy5qdEpWZKf7IQQUNsTaAreQRAZbIoYbfIiqKhtPc3ssJrtQvSY3D/IWQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=virtuozzo.com; dmarc=pass action=none header.from=openvz.org; dkim=pass header.d=openvz.org; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=openvz.org; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=9EPCyULGBca89daXLvU2x3D+5SJKQmqWm7yhdcd4uME=; b=fVWboo8vPdsE6w6t8ppVuG4+turFtRSLrBasJjPie3ZCMTqIcAtCgRswrBfPnYfZVrJs/s1fOFGazQgnFNfSws0jWpFGcJO/d+NNwSPbaWcE6+7mTQSp1UoIAdDaARPg7HlWEUFodcnrLbyiap8DlHy+RyKUTkFTZvHVt2tc+C0= Authentication-Results: vger.kernel.org; dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=none action=none header.from=openvz.org; Received: from AM6PR08MB4214.eurprd08.prod.outlook.com (2603:10a6:20b:8d::30) by AM5PR0801MB1716.eurprd08.prod.outlook.com (2603:10a6:203:39::18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4087.40; Tue, 4 May 2021 08:15:40 +0000 Received: from AM6PR08MB4214.eurprd08.prod.outlook.com ([fe80::fc46:c7a8:e09:8dfb]) by AM6PR08MB4214.eurprd08.prod.outlook.com ([fe80::fc46:c7a8:e09:8dfb%2]) with mapi id 15.20.4087.043; Tue, 4 May 2021 08:15:40 +0000 Subject: Re: [PATCH v4] KVM: x86: Fix KVM_GET_CPUID2 ioctl to return cpuid entries count To: Paolo Bonzini , Sean Christopherson , Valeriy Vdovin Cc: linux-kernel@vger.kernel.org, Jonathan Corbet , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Shuah Khan , Aaron Lewis , Alexander Graf , Andrew Jones , Oliver Upton , Like Xu , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20210428172729.3551-1-valeriy.vdovin@virtuozzo.com> <0d68dbc3-8462-7763-fbad-f3b895fcf6e6@redhat.com> <63e54361-0018-ad3b-fb2b-e5dba6a0f221@redhat.com> From: "Denis V. 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Lunev wrote: >> On 5/3/21 5:54 PM, Paolo Bonzini wrote: >>> On 29/04/21 03:00, Sean Christopherson wrote: >>>> On Wed, Apr 28, 2021, Valeriy Vdovin wrote: >>>>> It's very explicit by the code that it was designed to receive some >>>>> small number of entries to return E2BIG along with the corrected >>>>> number. >>>> >>>> LOL, saying KVM_GET_CPUID2 was "designed" is definitely giving the KVM >>>> forefathers the benefit of the doubt. >>> >>> I was going to make a different joke, i.e. that KVM_GET_CPUID2 was >>> indeed designed the way Valeriy described, but that design was >>> forgotten soon after. >>> >>> Really, this ioctl has been such a trainwreck that I think the only >>> good solution here is to drop it. >>> >>> Paolo >>> >> >> should we discuss KVM_GET_CPUID3 which will work "normally"? > > Is anybody using KVM_GET_CPUID2 at all? > > Paolo > As far as I understand only some testing within kernel now. Though we have plans to expose it for QAPI as the series in QEMU   [PATCH 1/2] qapi: fix error handling for x-vz-query-cpu-model-cpuid   [PATCH 2/2] qapi: blacklisted x-vz-query-cpu-model-cpuid in tests is not coming in a good way. The idea was to avoid manual code rework in QEMU and expose collected model at least for debug. All it all, some control over things set to the kernel as CPU modes is needed. Without that I am feeling uncomfortable. Den