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[209.132.180.67]) by mx.google.com with ESMTP id j6-v6si2850238pgs.615.2018.06.13.11.37.38; Wed, 13 Jun 2018 11:37:53 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 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 S935447AbeFMShJ (ORCPT + 99 others); Wed, 13 Jun 2018 14:37:09 -0400 Received: from mga01.intel.com ([192.55.52.88]:23474 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935070AbeFMShH (ORCPT ); Wed, 13 Jun 2018 14:37:07 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Jun 2018 11:37:07 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,220,1526367600"; d="scan'208";a="49093498" Received: from ray.jf.intel.com (HELO [10.7.201.133]) ([10.7.201.133]) by orsmga008.jf.intel.com with ESMTP; 13 Jun 2018 11:37:07 -0700 Subject: Re: [PATCHv3 14/17] x86/mm: Introduce direct_mapping_size To: "Kirill A. Shutemov" , Ingo Molnar , x86@kernel.org, Thomas Gleixner , "H. Peter Anvin" , Tom Lendacky References: <20180612143915.68065-1-kirill.shutemov@linux.intel.com> <20180612143915.68065-15-kirill.shutemov@linux.intel.com> Cc: Kai Huang , Jacob Pan , linux-kernel@vger.kernel.org, linux-mm@kvack.org From: Dave Hansen Openpgp: preference=signencrypt Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzShEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gPGRhdmVAc3I3MS5uZXQ+wsF7BBMBAgAlAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAUCTo3k0QIZAQAKCRBoNZUwcMmSsMO2D/421Xg8pimb9mPzM5N7khT0 2MCnaGssU1T59YPE25kYdx2HntwdO0JA27Wn9xx5zYijOe6B21ufrvsyv42auCO85+oFJWfE K2R/IpLle09GDx5tcEmMAHX6KSxpHmGuJmUPibHVbfep2aCh9lKaDqQR07gXXWK5/yU1Dx0r VVFRaHTasp9fZ9AmY4K9/BSA3VkQ8v3OrxNty3OdsrmTTzO91YszpdbjjEFZK53zXy6tUD2d e1i0kBBS6NLAAsqEtneplz88T/v7MpLmpY30N9gQU3QyRC50jJ7LU9RazMjUQY1WohVsR56d ORqFxS8ChhyJs7BI34vQusYHDTp6PnZHUppb9WIzjeWlC7Jc8lSBDlEWodmqQQgp5+6AfhTD kDv1a+W5+ncq+Uo63WHRiCPuyt4di4/0zo28RVcjtzlGBZtmz2EIC3vUfmoZbO/Gn6EKbYAn rzz3iU/JWV8DwQ+sZSGu0HmvYMt6t5SmqWQo/hyHtA7uF5Wxtu1lCgolSQw4t49ZuOyOnQi5 f8R3nE7lpVCSF1TT+h8kMvFPv3VG7KunyjHr3sEptYxQs4VRxqeirSuyBv1TyxT+LdTm6j4a mulOWf+YtFRAgIYyyN5YOepDEBv4LUM8Tz98lZiNMlFyRMNrsLV6Pv6SxhrMxbT6TNVS5D+6 UorTLotDZKp5+M7BTQRUY85qARAAsgMW71BIXRgxjYNCYQ3Xs8k3TfAvQRbHccky50h99TUY sqdULbsb3KhmY29raw1bgmyM0a4DGS1YKN7qazCDsdQlxIJp9t2YYdBKXVRzPCCsfWe1dK/q 66UVhRPP8EGZ4CmFYuPTxqGY+dGRInxCeap/xzbKdvmPm01Iw3YFjAE4PQ4hTMr/H76KoDbD cq62U50oKC83ca/PRRh2QqEqACvIH4BR7jueAZSPEDnzwxvVgzyeuhwqHY05QRK/wsKuhq7s UuYtmN92Fasbxbw2tbVLZfoidklikvZAmotg0dwcFTjSRGEg0Gr3p/xBzJWNavFZZ95Rj7Et db0lCt0HDSY5q4GMR+SrFbH+jzUY/ZqfGdZCBqo0cdPPp58krVgtIGR+ja2Mkva6ah94/oQN lnCOw3udS+Eb/aRcM6detZr7XOngvxsWolBrhwTQFT9D2NH6ryAuvKd6yyAFt3/e7r+HHtkU kOy27D7IpjngqP+b4EumELI/NxPgIqT69PQmo9IZaI/oRaKorYnDaZrMXViqDrFdD37XELwQ gmLoSm2VfbOYY7fap/AhPOgOYOSqg3/Nxcapv71yoBzRRxOc4FxmZ65mn+q3rEM27yRztBW9 AnCKIc66T2i92HqXCw6AgoBJRjBkI3QnEkPgohQkZdAb8o9WGVKpfmZKbYBo4pEAEQEAAcLB XwQYAQIACQUCVGPOagIbDAAKCRBoNZUwcMmSsJeCEACCh7P/aaOLKWQxcnw47p4phIVR6pVL e4IEdR7Jf7ZL00s3vKSNT+nRqdl1ugJx9Ymsp8kXKMk9GSfmZpuMQB9c6io1qZc6nW/3TtvK pNGz7KPPtaDzvKA4S5tfrWPnDr7n15AU5vsIZvgMjU42gkbemkjJwP0B1RkifIK60yQqAAlT YZ14P0dIPdIPIlfEPiAWcg5BtLQU4Wg3cNQdpWrCJ1E3m/RIlXy/2Y3YOVVohfSy+4kvvYU3 lXUdPb04UPw4VWwjcVZPg7cgR7Izion61bGHqVqURgSALt2yvHl7cr68NYoFkzbNsGsye9ft M9ozM23JSgMkRylPSXTeh5JIK9pz2+etco3AfLCKtaRVysjvpysukmWMTrx8QnI5Nn5MOlJj 1Ov4/50JY9pXzgIDVSrgy6LYSMc4vKZ3QfCY7ipLRORyalFDF3j5AGCMRENJjHPD6O7bl3Xo 4DzMID+8eucbXxKiNEbs21IqBZbbKdY1GkcEGTE7AnkA3Y6YB7I/j9mQ3hCgm5muJuhM/2Fr OPsw5tV/LmQ5GXH0JQ/TZXWygyRFyyI2FqNTx4WHqUn3yFj8rwTAU1tluRUYyeLy0ayUlKBH ybj0N71vWO936MqP6haFERzuPAIpxj2ezwu0xb1GjTk4ynna6h5GjnKgdfOWoRtoWndMZxbA z5cecg== Message-ID: <4ece14a4-27bd-e10a-4c2c-822c3e629dcd@intel.com> Date: Wed, 13 Jun 2018 11:37:07 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180612143915.68065-15-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/12/2018 07:39 AM, Kirill A. Shutemov wrote: > Kernel need to have a way to access encrypted memory. We are going to "The kernel needs"... > use per-KeyID direct mapping to facilitate the access with minimal > overhead. What are the security implications of this approach? > Direct mapping for each KeyID will be put next to each other in the That needs to be "a direct mapping" or "the direct mapping". It's missing an article to start the sentence. > virtual address space. We need to have a way to find boundaries of > direct mapping for particular KeyID. > > The new variable direct_mapping_size specifies the size of direct > mapping. With the value, it's trivial to find direct mapping for > KeyID-N: PAGE_OFFSET + N * direct_mapping_size. I think this deserves an update to Documentation/x86/x86_64/mm.txt, no? > Size of direct mapping is calculated during KASLR setup. If KALSR is > disable it happens during MKTME initialization. "disabled" > diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c > index 4408cd9a3bef..3d8ef8cb97e1 100644 > --- a/arch/x86/mm/kaslr.c > +++ b/arch/x86/mm/kaslr.c > @@ -69,6 +69,15 @@ static inline bool kaslr_memory_enabled(void) > return kaslr_enabled() && !IS_ENABLED(CONFIG_KASAN); > } > > +#ifndef CONFIG_X86_INTEL_MKTME > +static void __init setup_direct_mapping_size(void) > +{ > + direct_mapping_size = max_pfn << PAGE_SHIFT; > + direct_mapping_size = round_up(direct_mapping_size, 1UL << TB_SHIFT); > + direct_mapping_size += (1UL << TB_SHIFT) * CONFIG_MEMORY_PHYSICAL_PADDING; > +} > +#endif Comments, please. > /* Initialize base and padding for each memory region randomized with KASLR */ > void __init kernel_randomize_memory(void) > { > @@ -93,7 +102,11 @@ void __init kernel_randomize_memory(void) > if (!kaslr_memory_enabled()) > return; > > - kaslr_regions[0].size_tb = 1 << (__PHYSICAL_MASK_SHIFT - TB_SHIFT); > + /* > + * Upper limit for direct mapping size is 1/4 of whole virtual > + * address space > + */ > + kaslr_regions[0].size_tb = 1 << (__VIRTUAL_MASK_SHIFT - 1 - TB_SHIFT); Is this a cleanup that can be separate? > kaslr_regions[1].size_tb = VMALLOC_SIZE_TB; > > /* > @@ -101,8 +114,10 @@ void __init kernel_randomize_memory(void) > * add padding if needed (especially for memory hotplug support). > */ > BUG_ON(kaslr_regions[0].base != &page_offset_base); > - memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) + > - CONFIG_MEMORY_PHYSICAL_PADDING; > + > + setup_direct_mapping_size(); > + > + memory_tb = direct_mapping_size * mktme_nr_keyids + 1; What's the +1 for? Is "mktme_nr_keyids" 0 for "MKTME unsupported"? That needs to be called out, I think. > /* Adapt phyiscal memory region size based on available memory */ > if (memory_tb < kaslr_regions[0].size_tb) > diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c > index 43a44f0f2a2d..3e5322bf035e 100644 > --- a/arch/x86/mm/mktme.c > +++ b/arch/x86/mm/mktme.c > @@ -89,3 +89,51 @@ static bool need_page_mktme(void) > struct page_ext_operations page_mktme_ops = { > .need = need_page_mktme, > }; > + > +void __init setup_direct_mapping_size(void) > +{ > + unsigned long available_va; > + > + /* 1/4 of virtual address space is didicated for direct mapping */ > + available_va = 1UL << (__VIRTUAL_MASK_SHIFT - 1); > + > + /* How much memory the systrem has? */ > + direct_mapping_size = max_pfn << PAGE_SHIFT; > + direct_mapping_size = round_up(direct_mapping_size, 1UL << 40); > + > + if (mktme_status != MKTME_ENUMERATED) > + goto out; > + > + /* > + * Not enough virtual address space to address all physical memory with > + * MKTME enabled. Even without padding. > + * > + * Disable MKTME instead. > + */ > + if (direct_mapping_size > available_va / mktme_nr_keyids + 1) { > + pr_err("x86/mktme: Disabled. Not enough virtual address space\n"); > + pr_err("x86/mktme: Consider switching to 5-level paging\n"); > + mktme_disable(); > + goto out; > + } > + > + /* > + * Virtual address space is divided between per-KeyID direct mappings. > + */ > + available_va /= mktme_nr_keyids + 1; > +out: > + /* Add padding, if there's enough virtual address space */ > + direct_mapping_size += (1UL << 40) * CONFIG_MEMORY_PHYSICAL_PADDING; > + if (direct_mapping_size > available_va) > + direct_mapping_size = available_va; > +} Do you really need two copies of this function? Shouldn't it see mktme_status!=MKTME_ENUMERATED and just jump out? How is the code before that "goto out" different from the CONFIG_MKTME=n case?