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 9CF38C433F5 for ; Thu, 7 Apr 2022 01:07:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233303AbiDGBJx (ORCPT ); Wed, 6 Apr 2022 21:09:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48366 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233147AbiDGBJt (ORCPT ); Wed, 6 Apr 2022 21:09:49 -0400 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C5C2417FD13; Wed, 6 Apr 2022 18:07:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1649293671; x=1680829671; h=message-id:subject:from:to:cc:date:in-reply-to: references:mime-version:content-transfer-encoding; bh=hH9j1C11zEDzX1YDHVkD28XC3kD9po5unUNqNLEfqd0=; b=C1RJUatMl69uDGBq7FGEf5vrGYPVhoZMG3Sr2Ph2FH9frSRqrcPH1p2s 0KEiDEb/tgwco7bQWenMu6TObSavxJMPfT11eHkzI8lXB7eBJNcC1UrC6 IKHppaucLWbqrCgRA9aFS9NBLJEwc/WTvE5N63fHNajJBK0rtN4CTZwi3 1ejngg8J4D/hwucFTIZhMbx7WRt05IhXHGS7I1Qbm8zH2Shj3xaUurZom mBNKNRsi+uttjt9GcaJc8kspuCS42NPBqspE8k9hO6WbDtpkm56tseSR+ r3wQu/brYNKz1hue3REgi/r6uDG/+Ys++dLCNaZlBp9K7uEOs80dfeGbK w==; X-IronPort-AV: E=McAfee;i="6200,9189,10309"; a="261375314" X-IronPort-AV: E=Sophos;i="5.90,241,1643702400"; d="scan'208";a="261375314" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Apr 2022 18:07:43 -0700 X-IronPort-AV: E=Sophos;i="5.90,241,1643702400"; d="scan'208";a="588601314" Received: from mgailhax-mobl.amr.corp.intel.com (HELO khuang2-desk.gar.corp.intel.com) ([10.254.55.23]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Apr 2022 18:07:40 -0700 Message-ID: Subject: Re: [RFC PATCH v5 026/104] KVM: TDX: x86: Add vm ioctl to get TDX systemwide parameters From: Kai Huang To: Xiaoyao Li , Paolo Bonzini , isaku.yamahata@intel.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: isaku.yamahata@gmail.com, Jim Mattson , erdemaktas@google.com, Connor Kuehl , Sean Christopherson Date: Thu, 07 Apr 2022 13:07:38 +1200 In-Reply-To: <17981a2e-03e3-81df-0654-5ccb29f43546@intel.com> References: <5ff08ce32be458581afe59caa05d813d0e4a1ef0.1646422845.git.isaku.yamahata@intel.com> <586be87a-4f81-ea43-2078-a6004b4aba08@redhat.com> <17981a2e-03e3-81df-0654-5ccb29f43546@intel.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.4 (3.42.4-1.fc35) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2022-04-06 at 09:54 +0800, Xiaoyao Li wrote: > On 4/5/2022 8:52 PM, Paolo Bonzini wrote: > > On 3/4/22 20:48, isaku.yamahata@intel.com wrote: > > > Implement a VM-scoped subcomment to get system-wide parameters.  Although > > > this is system-wide parameters not per-VM, this subcomand is VM-scoped > > > because > > > - Device model needs TDX system-wide parameters after creating KVM VM. > > > - This subcommands requires to initialize TDX module.  For lazy > > >    initialization of the TDX module, vm-scope ioctl is better. > > > > Since there was agreement to install the TDX module on load, please > > place this ioctl on the /dev/kvm file descriptor. > > > > At least for SEV, there were cases where the system-wide parameters are > > needed outside KVM, so it's better to avoid requiring a VM file descriptor. > > I don't have strong preference on KVM-scope ioctl or VM-scope. > > Initially, we made it KVM-scope and change it to VM-scope in this > version. Yes, it returns the info from TDX module, which doesn't vary > per VM. However, what if we want to return different capabilities > (software controlled capabilities) per VM?  > In this case, you don't return different capabilities, instead, you return the same capabilities but control the capabilities on per-VM basis. > Part of the TDX capabilities > serves like get_supported_cpuid, making it KVM wide lacks the > flexibility to return differentiated capabilities for different TDs. > > > > Thanks, > > > > Paolo > > >