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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 392DBC433ED for ; Mon, 26 Apr 2021 18:04:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0324E613BB for ; Mon, 26 Apr 2021 18:04:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234595AbhDZSEj (ORCPT ); Mon, 26 Apr 2021 14:04:39 -0400 Received: from mga04.intel.com ([192.55.52.120]:22343 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234148AbhDZSDe (ORCPT ); Mon, 26 Apr 2021 14:03:34 -0400 IronPort-SDR: kbUIcSiUQuDuo4K3U5xpw1d2AWSF/mlYNC9lgwzLFm9aY6bEZKAFUedXxlMGbmlFmR5943Z5lP P6gEsoIb/UpA== X-IronPort-AV: E=McAfee;i="6200,9189,9966"; a="194263258" X-IronPort-AV: E=Sophos;i="5.82,252,1613462400"; d="scan'208";a="194263258" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Apr 2021 11:02:50 -0700 IronPort-SDR: TZoklZsXDchjOM4p2zZP7e3bYTlApnrnKHxrPMqoDZMFUplpEIZNxZjDe13rn6YqcZGnsZZibw OgIHWi4lETWQ== X-IronPort-AV: E=Sophos;i="5.82,252,1613462400"; d="scan'208";a="447353400" Received: from ssumanpx-mobl.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.254.34.197]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Apr 2021 11:02:49 -0700 From: Kuppuswamy Sathyanarayanan To: Peter Zijlstra , Andy Lutomirski , Dave Hansen , Dan Williams , Tony Luck Cc: Andi Kleen , Kirill Shutemov , Kuppuswamy Sathyanarayanan , Raj Ashok , Sean Christopherson , linux-kernel@vger.kernel.org, Kuppuswamy Sathyanarayanan Subject: [RFC v2 16/32] x86/tdx: Handle MWAIT, MONITOR and WBINVD Date: Mon, 26 Apr 2021 11:01:43 -0700 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When running as a TDX guest, there are a number of existing, privileged instructions that do not work. If the guest kernel uses these instructions, the hardware generates a #VE. You can find the list of unsupported instructions in Intel Trust Domain Extensions (Intel® TDX) Module specification, sec 9.2.2 and in Guest-Host Communication Interface (GHCI) Specification for Intel TDX, sec 2.4.1.     To prevent TD guest from using MWAIT/MONITOR instructions, support for these instructions are already disabled by TDX module (SEAM). So CPUID flags for these instructions should be in disabled state. After the above mentioned preventive measures, if TD guests still execute these instructions, add appropriate warning messages in #VE handler. For WBIND instruction, since it's related to memory writeback and cache flushes, it's mainly used in context of IO devices. Since TDX 1.0 does not support non-virtual I/O devices, skipping it should not cause any fatal issues. But to let users know about its usage, use WARN() to report about it.. For MWAIT/MONITOR instruction, since its unsupported use WARN() to report unsupported usage. Signed-off-by: Kuppuswamy Sathyanarayanan Reviewed-by: Andi Kleen --- arch/x86/kernel/tdx.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c index 3fe617978fc4..294dda5bf3f6 100644 --- a/arch/x86/kernel/tdx.c +++ b/arch/x86/kernel/tdx.c @@ -371,6 +371,21 @@ int tdg_handle_virtualization_exception(struct pt_regs *regs, case EXIT_REASON_EPT_VIOLATION: ve->instr_len = tdg_handle_mmio(regs, ve); break; + case EXIT_REASON_WBINVD: + /* + * WBINVD is not supported inside TDX guests. All in- + * kernel uses should have been disabled. + */ + WARN_ONCE(1, "TD Guest used unsupported WBINVD instruction\n"); + break; + case EXIT_REASON_MONITOR_INSTRUCTION: + case EXIT_REASON_MWAIT_INSTRUCTION: + /* + * Something in the kernel used MONITOR or MWAIT despite + * X86_FEATURE_MWAIT being cleared for TDX guests. + */ + WARN_ONCE(1, "TD Guest used unsupported MWAIT/MONITOR instruction\n"); + break; default: pr_warn("Unexpected #VE: %lld\n", ve->exit_reason); return -EFAULT; -- 2.25.1