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[23.128.96.18]) by mx.google.com with ESMTP id s14si289562ejx.539.2021.05.19.11.22.21; Wed, 19 May 2021 11:22:45 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350485AbhERP6C (ORCPT + 99 others); Tue, 18 May 2021 11:58:02 -0400 Received: from mga06.intel.com ([134.134.136.31]:9116 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350480AbhERP6B (ORCPT ); Tue, 18 May 2021 11:58:01 -0400 IronPort-SDR: Wg7Xxm0+6SdiTfWvPYNC0a1D/taf9/9E8ZCsTcBxuc/diuwx2EcGQnmnsl2h4kfTp+gbv3jqnh kpcZkywCniqA== X-IronPort-AV: E=McAfee;i="6200,9189,9988"; a="261974806" X-IronPort-AV: E=Sophos;i="5.82,310,1613462400"; d="scan'208";a="261974806" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 May 2021 08:56:10 -0700 IronPort-SDR: x6Ts4XVbUTkCy3GvhgsJgXVNM26SQLdG2T93Ot6Nsv0MPPL4XaopzM0neSXcYs1lzD2773UzfL okreloKb4Anw== X-IronPort-AV: E=Sophos;i="5.82,310,1613462400"; d="scan'208";a="542022224" Received: from craigsmi-mobl.amr.corp.intel.com (HELO [10.212.132.228]) ([10.212.132.228]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 May 2021 08:56:09 -0700 Subject: Re: [RFC v2-fix 1/1] x86/traps: Add #VE support for TDX guest To: Andi Kleen , Kuppuswamy Sathyanarayanan , Peter Zijlstra , Andy Lutomirski Cc: Tony Luck , Kirill Shutemov , Kuppuswamy Sathyanarayanan , Dan Williams , Raj Ashok , Sean Christopherson , linux-kernel@vger.kernel.org, Sean Christopherson References: <20210518000957.257869-1-sathyanarayanan.kuppuswamy@linux.intel.com> <4fc32900-412d-fa10-520e-afa6caade33e@intel.com> <81c0f447-44b8-c2b6-ce41-a39ec0a1832b@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: <81c0f447-44b8-c2b6-ce41-a39ec0a1832b@linux.intel.com> 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 5/18/21 8:45 AM, Andi Kleen wrote: > > On 5/18/2021 8:11 AM, Dave Hansen wrote: >> On 5/17/21 5:09 PM, Kuppuswamy Sathyanarayanan wrote: >>> After TDGETVEINFO #VE could happen in theory (e.g. through an NMI), >>> although we don't expect it to happen because we don't expect NMIs to >>> trigger #VEs. Another case where they could happen is if the #VE >>> exception panics, but in this case there are no guarantees on anything >>> anyways. >> This implies: "we do not expect any NMI to do MMIO".  Is that true?  Why? > > Only drivers that are not supported in TDX anyways could do it (mainly > watchdog drivers) No APIC access either? Also, shouldn't we have at least a: WARN_ON_ONCE(in_nmi()); if we don't expect (or handle well) #VE in NMIs?