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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37506C433F5 for ; Sun, 17 Oct 2021 17:15:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B82560FE3 for ; Sun, 17 Oct 2021 17:15:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344353AbhJQRRi (ORCPT ); Sun, 17 Oct 2021 13:17:38 -0400 Received: from mga01.intel.com ([192.55.52.88]:44281 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230420AbhJQRRg (ORCPT ); Sun, 17 Oct 2021 13:17:36 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10140"; a="251580226" X-IronPort-AV: E=Sophos;i="5.85,380,1624345200"; d="scan'208";a="251580226" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Oct 2021 10:15:26 -0700 X-IronPort-AV: E=Sophos;i="5.85,380,1624345200"; d="scan'208";a="526002505" Received: from pmmccorm-mobl1.amr.corp.intel.com (HELO [10.209.54.168]) ([10.209.54.168]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Oct 2021 10:15:25 -0700 Subject: Re: [PATCH v8 06/11] x86/traps: Add #VE support for TDX guest To: Borislav Petkov , Kuppuswamy Sathyanarayanan Cc: Thomas Gleixner , Ingo Molnar , x86@kernel.org, Paolo Bonzini , David Hildenbrand , Andrea Arcangeli , Josh Poimboeuf , Juergen Gross , Deep Shah , VMware Inc , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Peter H Anvin , Tony Luck , Dan Williams , Andi Kleen , Kirill Shutemov , Sean Christopherson , Kuppuswamy Sathyanarayanan , linux-kernel@vger.kernel.org References: <20211005025205.1784480-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20211005025205.1784480-7-sathyanarayanan.kuppuswamy@linux.intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/7/21 10:06 AM, Borislav Petkov wrote: > On Mon, Oct 04, 2021 at 07:52:00PM -0700, Kuppuswamy Sathyanarayanan wrote: >> +unsigned long tdx_get_ve_info(struct ve_info *ve) >> +{ >> + struct tdx_module_output out = {0}; >> + u64 ret; >> + >> + /* >> + * NMIs and machine checks are suppressed. Before this point any >> + * #VE is fatal. After this point (TDGETVEINFO call), NMIs and >> + * additional #VEs are permitted (but it is expected not to >> + * happen unless kernel panics). >> + */ >> + ret = __tdx_module_call(TDGETVEINFO, 0, 0, 0, 0, &out); > Same question as before - why do you need to clear this @out thing above > when __tdx_module_call() will overwrite it? > > What you should do instead is check that @ve pointer which you get > passed in - it might be NULL. Hi Borislav, That ve_info really is specific to handling a fault. There's only one call site: > +DEFINE_IDTENTRY(exc_virtualization_exception) > +{ > + struct ve_info ve; ... > + ret = tdx_get_ve_info(&ve); I think it's equivalent to something like a 'pt_regs' or 'stack_info' that we pass around in other exception handlers. It's always stack allocated. It's never dynamically allocated and NULL is never passed for some other semantic reason.