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[23.128.96.18]) by mx.google.com with ESMTP id c30si7710209pgn.588.2021.05.07.14.53.59; Fri, 07 May 2021 14:54:12 -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 S229542AbhEGVxZ (ORCPT + 99 others); Fri, 7 May 2021 17:53:25 -0400 Received: from mga07.intel.com ([134.134.136.100]:60249 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229470AbhEGVxY (ORCPT ); Fri, 7 May 2021 17:53:24 -0400 IronPort-SDR: QFrrQXSUhwGEnRc2qt6lh09nGWqUGLqz+Nnfbj+C1VCR9Q7r1Vgagu/uKzedBKocrY1oZH3KLn bbaECuKd7cxA== X-IronPort-AV: E=McAfee;i="6200,9189,9977"; a="262757894" X-IronPort-AV: E=Sophos;i="5.82,282,1613462400"; d="scan'208";a="262757894" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 May 2021 14:52:24 -0700 IronPort-SDR: DXwnKmF2N0/E3L3nPr1tpvCL0lDLEf/KmkBp+/z+nqXxxXWnaA7+T2DLpVZYBfECRcdyIxcNGx MQoVtsTFOM5A== X-IronPort-AV: E=Sophos;i="5.82,282,1613462400"; d="scan'208";a="431679354" Received: from msandrid-mobl.amr.corp.intel.com (HELO [10.212.134.124]) ([10.212.134.124]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 May 2021 14:52:23 -0700 Subject: Re: [RFC v2 15/32] x86/tdx: Handle in-kernel MMIO To: Kuppuswamy Sathyanarayanan , Peter Zijlstra , Andy Lutomirski , Dan Williams , Tony Luck Cc: Andi Kleen , Kirill Shutemov , Kuppuswamy Sathyanarayanan , Raj Ashok , Sean Christopherson , linux-kernel@vger.kernel.org References: <38eb0c5dce2e2ff6bdab4dffbead09780ec86e50.1619458733.git.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: <38eb0c5dce2e2ff6bdab4dffbead09780ec86e50.1619458733.git.sathyanarayanan.kuppuswamy@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 4/26/21 11:01 AM, Kuppuswamy Sathyanarayanan wrote: > Handle #VE due to MMIO operations. MMIO triggers #VE with EPT_VIOLATION > exit reason. This needs a bit of a history lesson. "In traditional VMs, MMIO tends to be implemented by giving a guest access to an mapping which will cause a VMEXIT on access. That's not possible in a TDX guest..." > For now we only handle subset of instruction that kernel uses for MMIO > oerations. User-space access triggers SIGBUS. I still don't think that TDX guests should be doing things that they *KNOW* will cause #VE, including MMIO. I really want to hear a more discrete story about why this is the *best* way to do this for Linux instead of just a hack from the Windows binary driver ecosystem that seemed expedient.