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 X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1FDD0C433B4 for ; Thu, 1 Apr 2021 20:06:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E0FA561006 for ; Thu, 1 Apr 2021 20:06:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234697AbhDAUGe (ORCPT ); Thu, 1 Apr 2021 16:06:34 -0400 Received: from mga02.intel.com ([134.134.136.20]:45509 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234287AbhDAUGd (ORCPT ); Thu, 1 Apr 2021 16:06:33 -0400 IronPort-SDR: PIQHFYyPXXuknLwtyuzXwLbUOa16tJwKkT2J8pnHze3xpK7LsCMO90fkTaUZ+iZL/G1kgcG06w 9OWkCThqbTSw== X-IronPort-AV: E=McAfee;i="6000,8403,9941"; a="179454389" X-IronPort-AV: E=Sophos;i="5.81,296,1610438400"; d="scan'208";a="179454389" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Apr 2021 13:06:33 -0700 IronPort-SDR: KFs5kMk14y7tyfv8Sqq05NSBIUus/kmxXMKnxhsyOHy/cPO62WYvGcUJrPPRToAi0GyGFLvmH2 nzb4Ffx6HKEA== X-IronPort-AV: E=Sophos;i="5.81,296,1610438400"; d="scan'208";a="611046689" Received: from pzlai-mobl.amr.corp.intel.com (HELO [10.213.169.242]) ([10.213.169.242]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Apr 2021 13:06:29 -0700 Subject: Re: [RFC v1 21/26] x86/mm: Move force_dma_unencrypted() to common code To: Kuppuswamy Sathyanarayanan , Peter Zijlstra , Andy Lutomirski Cc: Andi Kleen , Kirill Shutemov , Kuppuswamy Sathyanarayanan , Dan Williams , Raj Ashok , Sean Christopherson , linux-kernel@vger.kernel.org References: <444fe9c7c035417f6abc3e0be2a4861cb573ab28.1612563142.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: <444fe9c7c035417f6abc3e0be2a4861cb573ab28.1612563142.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 2/5/21 3:38 PM, Kuppuswamy Sathyanarayanan wrote: > From: "Kirill A. Shutemov" > > Intel TDX doesn't allow VMM to access guest memory. Any memory that is > required for communication with VMM suppose to be shared explicitly by s/suppose to/must/ > setting the bit in page table entry. The shared memory is similar to > unencrypted memory in AMD SME/SEV terminology. In addition to setting the page table bit, there's also a dance to go through to convert the memory. Please mention the procedure here at least. It's very different from SME. > force_dma_unencrypted() has to return true for TDX guest. Move it out of > AMD SME code. You lost me here. What does force_dma_unencrypted() have to do with host/guest shared memory? > Introduce new config option X86_MEM_ENCRYPT_COMMON that has to be > selected by all x86 memory encryption features. Please also mention what will set it. I assume TDX guest support will set this option. It's probably also worth a sentence to say that force_dma_unencrypted() will have TDX-specific code added to it. (It will, right??) > This is preparation for TDX changes in DMA code. Probably best to also mention that this effectively just moves code around. This patch should have no functional changes at runtime. > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 0374d9f262a5..8fa654d61ac2 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1538,14 +1538,18 @@ config X86_CPA_STATISTICS > helps to determine the effectiveness of preserving large and huge > page mappings when mapping protections are changed. > > +config X86_MEM_ENCRYPT_COMMON > + select ARCH_HAS_FORCE_DMA_UNENCRYPTED > + select DYNAMIC_PHYSICAL_MASK > + def_bool n > + > config AMD_MEM_ENCRYPT > bool "AMD Secure Memory Encryption (SME) support" > depends on X86_64 && CPU_SUP_AMD > select DMA_COHERENT_POOL > - select DYNAMIC_PHYSICAL_MASK > select ARCH_USE_MEMREMAP_PROT > - select ARCH_HAS_FORCE_DMA_UNENCRYPTED > select INSTRUCTION_DECODER > + select X86_MEM_ENCRYPT_COMMON > help > Say yes to enable support for the encryption of system memory. > This requires an AMD processor that supports Secure Memory > diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h > index 30a3b30395ad..95e534cffa99 100644 > --- a/arch/x86/include/asm/io.h > +++ b/arch/x86/include/asm/io.h > @@ -257,10 +257,12 @@ static inline void slow_down_io(void) > > #endif > > -#ifdef CONFIG_AMD_MEM_ENCRYPT > #include > > extern struct static_key_false sev_enable_key; This _looks_ odd. sev_enable_key went from being under CONFIG_AMD_MEM_ENCRYPT to being unconditionally referenced. Could you explain a bit more? I would have expected it tot at *least* be tied to the new #ifdef. > +#ifdef CONFIG_AMD_MEM_ENCRYPT > + > static inline bool sev_key_active(void) > { > return static_branch_unlikely(&sev_enable_key); > diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile > index 5864219221ca..b31cb52bf1bd 100644 > --- a/arch/x86/mm/Makefile ...