Received: by 2002:a05:6a10:9848:0:0:0:0 with SMTP id x8csp3748002pxf; Mon, 29 Mar 2021 10:16:12 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxYLJK1sKwNOZD7Po4jYfH6saDDdzokYlw50WPMnmJG3LZdm0C21L5ho+wenlFYfL6jCo0H X-Received: by 2002:aa7:d54c:: with SMTP id u12mr30560629edr.234.1617038171890; Mon, 29 Mar 2021 10:16:11 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1617038171; cv=none; d=google.com; s=arc-20160816; b=XoZzGv0l3mszWMJ2PLXq0pQ5oFEZyQJuAHsgq+wL7MJlxBBQqpzZCDubWSPbXVsLVW Jb3SErB0+ZWRKWV/utcmRbA64QPcw/DqhGHGElV/QWbBxgeEAxHhn1megbvD4cZG1j8i gUVo+8/6yQW0Ml8R6EoA1mAOHgcaIMlPvjvfyV1vhplFvbfU0PgiI+3GhMdXZvatCKT4 LQizpK9CPVCNKAJFIrgiLVOcrKd9abvkgHM0sCh5nlmR4WrGghVjGr3WF5EY4uYM7tKG OlsJqu/RZOUHpA8H34mTV5tZ6H7v/rEFyf9d8t8No2qsOrNzK1gMIeaEwC/xnCC7mydK E7Zw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:content-language :in-reply-to:mime-version:user-agent:date:message-id:autocrypt:from :references:cc:to:subject:ironport-sdr:ironport-sdr; bh=sBj7k6T9J2FKJ1kC4XsAtfsnxVbC9mwI7rEBPRGD6PQ=; b=x2P61h11pfHp/qMfuX1otdfU8zQJcQmLjMs4pjAgJbXg8/Y7b9UK2BGDJRIuc6BGbU lz1nY2GPPSxVok0Q0ZAjSbXx9NgOUNeC6ml+Yv8pPDhINnPfhj0dAZjfUMm1gx5gSYhF 3f4Mpv7J2+wVKUacBTwNcuYKslb//WJofvUCrONdl1N006E6KSUc3MHqJ/rnNVfowAaN OIO6BbFpDzO1X9/tXfJYubJeyZLzY19an34eEV3H0s5o+kxY54NRF8k2EnUl88P8vHRD Vp1cCcwpFjR/e5ACFg2HBYfhQvXE8UvfaoOP4n7HUpVBOjbLE0IWis0CK0rCql1tewSE +Chw== ARC-Authentication-Results: i=1; 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 Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id ga24si14030331ejc.422.2021.03.29.10.15.48; Mon, 29 Mar 2021 10:16:11 -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 S230421AbhC2ROa (ORCPT + 99 others); Mon, 29 Mar 2021 13:14:30 -0400 Received: from mga12.intel.com ([192.55.52.136]:44199 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230180AbhC2ROV (ORCPT ); Mon, 29 Mar 2021 13:14:21 -0400 IronPort-SDR: QKsZ6GYFDKbyrxp47QrhjPuOf/NLOzXLemUV6itb8esuPRTz2kR1oYQ3WEwSfdg1qPrPDCaGEW m8mrLqk8qDZw== X-IronPort-AV: E=McAfee;i="6000,8403,9938"; a="170993092" X-IronPort-AV: E=Sophos;i="5.81,288,1610438400"; d="scan'208";a="170993092" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Mar 2021 10:14:04 -0700 IronPort-SDR: UIlrC4QBtgYKxbFN0RpkEVmt7DpM8EkfDTMtTO2FOjjiktxB+oOYJPPNN6RdqCndmr0OGu8gjy xui0bdMYjosA== X-IronPort-AV: E=Sophos;i="5.81,288,1610438400"; d="scan'208";a="411183887" Received: from jmwolcot-mobl.amr.corp.intel.com (HELO [10.209.158.84]) ([10.209.158.84]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Mar 2021 10:14:03 -0700 Subject: Re: [PATCH v2 1/1] x86/tdx: Handle MWAIT, MONITOR and WBINVD 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: <91C0F6F1-B8C3-4130-B903-C63CD4B87F3F@amacapital.net> From: Dave Hansen 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: <498f078c-5196-a608-7f1a-8425ff056135@intel.com> Date: Mon, 29 Mar 2021 10:14:02 -0700 User-Agent: Mozilla/5.0 (X11; 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 3/27/21 3:54 PM, Kuppuswamy Sathyanarayanan wrote: > + /* > + * Per Guest-Host-Communication Interface (GHCI) for Intel Trust > + * Domain Extensions (Intel TDX) specification, sec 2.4, > + * some instructions that unconditionally cause #VE (such as WBINVD, > + * MONITOR, MWAIT) do not have corresponding TDCALL > + * [TDG.VP.VMCALL ] leaves, since the TD has been designed > + * with no deterministic way to confirm the result of those operations > + * performed by the host VMM. In those cases, the goal is for the TD > + * #VE handler to increment the RIP appropriately based on the VE > + * information provided via TDCALL. > + */ That's an awfully big comment. Could you pare it down, please? Maybe focus on the fact that we should never get here and why, rather than talking about some silly spec? > + case EXIT_REASON_WBINVD: > + pr_warn_once("WBINVD #VE Exception\n"); I actually think WBINVD in here should oops. We use it for some really important things. If it can't be executed, and we're depending on it, the kernel is in deep, deep trouble. I think a noop here is dangerous. > + case EXIT_REASON_MONITOR_INSTRUCTION: > + /* Handle as nops. */ > + break; MONITOR is a privileged instruction, right? So we can only end up in here if the kernel screws up and isn't reading CPUID correctly, right? That dosen't seem to me like something we want to suppress. This needs a warning, at least. I assume that having a MONITOR instruction immediately return doesn't do any harm. > + case EXIT_REASON_MWAIT_INSTRUCTION: > + /* MWAIT is supressed, not supposed to reach here. */ > + WARN(1, "MWAIT unexpected #VE Exception\n"); > + return -EFAULT; How is MWAIT "supppressed"?