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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BC676C433EF for ; Tue, 14 Dec 2021 10:41:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233120AbhLNKlV (ORCPT ); Tue, 14 Dec 2021 05:41:21 -0500 Received: from mga11.intel.com ([192.55.52.93]:11473 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231272AbhLNKlU (ORCPT ); Tue, 14 Dec 2021 05:41:20 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1639478480; x=1671014480; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=RASC9tkX/qeuaKuqj+j/co1PDOniTmejosj0dqMzGoY=; b=eLrf2ie+oolgksZuhA57dGNLMvdT1g4VmQkuuLkCDUawgbxQCJKaT55E S+T6riA2KvoZbI5GeEKndRsDbdlC6xWe403fiKUVIlORzY4QpWV4FKAJX JzLOCSrm9hJNFQrugWRxW7uaLlLtilZscHOeDUmduOJ6TGSKsRmR4PLGM gKrzSiKnB1EY1F9DM4iiF3TWG2y2kUQe6rlVx9uqF6ylHRSoDy74uG2Wa uhrLV+ePglyC2O/meisv1HCHJMYTQq9ma/FYVYXYLRwuEAFhndEhjyTG8 OSMLbb5qgegvENc/v3tDVFYDP5rfVnFkDoyWGKbAO6B41sDWCkVHHYg+8 Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10197"; a="236483828" X-IronPort-AV: E=Sophos;i="5.88,205,1635231600"; d="scan'208";a="236483828" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Dec 2021 02:41:20 -0800 X-IronPort-AV: E=Sophos;i="5.88,205,1635231600"; d="scan'208";a="518181709" Received: from yangzhon-virtual.bj.intel.com (HELO yangzhon-Virtual) ([10.238.144.101]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-SHA256; 14 Dec 2021 02:41:16 -0800 Date: Tue, 14 Dec 2021 18:26:19 +0800 From: Yang Zhong To: Paolo Bonzini Cc: x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, seanjc@google.com, jun.nakajima@intel.com, kevin.tian@intel.com, jing2.liu@linux.intel.com, jing2.liu@intel.com, yang.zhong@intel.com Subject: Re: [PATCH 10/19] kvm: x86: Emulate WRMSR of guest IA32_XFD Message-ID: <20211214102619.GA25456@yangzhon-Virtual> References: <20211208000359.2853257-1-yang.zhong@intel.com> <20211208000359.2853257-11-yang.zhong@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 10, 2021 at 05:02:49PM +0100, Paolo Bonzini wrote: > First, the MSR should be added to msrs_to_save_all and > kvm_cpu_cap_has(X86_FEATURE_XFD) should be checked in > kvm_init_msr_list. > > It seems that RDMSR support is missing, too. > > More important, please include: > > - documentation for the new KVM_EXIT_* value > > - a selftest that explains how userspace should react to it. > > This is a strong requirement for any new API (the first has been for > years; but the latter is also almost always respected these days). > This series should not have been submitted without documentation. > > Also: > > On 12/8/21 01:03, Yang Zhong wrote: > > > >+ if (!guest_cpuid_has(vcpu, X86_FEATURE_XFD)) > >+ return 1; > > This should allow msr->host_initiated always (even if XFD is not > part of CPUID). However, if XFD is nonzero and > kvm_check_guest_realloc_fpstate returns true, then it should return > 1. > > The selftest should also cover using KVM_GET_MSR/KVM_SET_MSR. > Paolo, Seems we do not need new KVM_EXIT_* again from below thomas' new patchset: git://git.kernel.org/pub/scm/linux/kernel/git/people/tglx/devel.git x86/fpu-kvm So the selftest stll need support KVM_GET_MSR/KVM_SET_MSR for MSR_IA32_XFD and MSR_IA32_XFD_ERR? If yes, we only do some read/write test with vcpu_set_msr()/ vcpu_get_msr() from new selftest tool? or do wrmsr from guest side and check this value from selftest side? I checked some msr selftest reference code, tsc_msrs_test.c, which maybe better for this reference. If you have better suggestion, please share it to me. thanks! Yang