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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 510E9C001DC for ; Sat, 22 Jul 2023 04:53:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231355AbjGVExc (ORCPT ); Sat, 22 Jul 2023 00:53:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231362AbjGVExR (ORCPT ); Sat, 22 Jul 2023 00:53:17 -0400 Received: from BN6PR00CU002.outbound.protection.outlook.com (mail-eastus2azon11021014.outbound.protection.outlook.com [52.101.57.14]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 19CE94681; Fri, 21 Jul 2023 21:52:25 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=Xo9lthHa9LaSHq5rLKL35h3do0qZGg7wM7CRSWLrfht42KIizNnic7/MWPbznwwnHDzBwNgDvSR06pqxRRxAL/GRmDbZKaDpODGCVEkhX1Ch5jPw32SWqYMlIr36huqcxyYE63A4hB/6KuaaeHr7pIbDxWLl7qLkwdbNIQ5M1HoaT1duYVlR1QorRjjV/AtNGj4261skkn2DCRxV1ivCz9xUXU6SoPuK/n2PjUj9j7WTpe6LVeqw7+xoxf5gWLc7jpkeRYlFP8uQ//efjg4LxtnyfOr58GSHq126LCiwDjrb1u7wnWQwnqch21g8SkWcfknws0cFPXtLKhpYNnAA7g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=tCKTySSFMZnk9HDozdvtLUHwrBvy/tfwM/1wBsXPV74=; b=BdCEfRQHqjgQ5oQh19Z3IljfsC5TZpeD5betzWYNk2rEl0Rz5Y23C4ci8MD7BbvNxFEo86RjYRMSoNf2+/LLpJ+fd1ZjqQS2SKrJx7WLR8D3SpJB+oomWby7Pl9tI919xbE7dU3CbCZpPU/uYvLh1TK9GTNnQZstOkhVuvgLUrnQt51lpoA5n+W3/2ik9drKgAw8HLiHBo/gwf3sccfPt3qI1pvQNtHRDoAgjFfc4LKH85DtZDf3J2JK9Glv6ACHG/xGAl2pdrdPho1/F7teLjKHc4DQcpNAkXPZCG+vxr7RzIUW8Xs6PTb1IMQ261eyO+QlTuK1ptgWaocOM10nSA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=microsoft.com; dmarc=pass action=none header.from=microsoft.com; dkim=pass header.d=microsoft.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=tCKTySSFMZnk9HDozdvtLUHwrBvy/tfwM/1wBsXPV74=; b=ZrWaum5iebJM7tUm6Ue2wtZmT4s7Rm2VScuykOHozn6IuCMVOkwO+6IK09LIurFmBVZAihtMh2BFnZu1LxqvhuPHX5DD8EB9oey62PKsGRLdHPYwwvwrGNva8+1ABOkZB3Yr5S1DnNqN+OFxTAGQXagdpndXe6UTcH4+BlbD9iA= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=microsoft.com; Received: from DM6PR21MB1370.namprd21.prod.outlook.com (2603:10b6:5:16b::28) by DM4PR21MB3416.namprd21.prod.outlook.com (2603:10b6:8:b3::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6631.16; Sat, 22 Jul 2023 04:51:41 +0000 Received: from DM6PR21MB1370.namprd21.prod.outlook.com ([fe80::58ed:9fb:47a9:13df]) by DM6PR21MB1370.namprd21.prod.outlook.com ([fe80::58ed:9fb:47a9:13df%7]) with mapi id 15.20.6631.014; Sat, 22 Jul 2023 04:51:40 +0000 From: Michael Kelley To: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, peterz@infradead.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org Cc: mikelley@microsoft.com, stable@vger.kernel.org Subject: [PATCH v2 1/1] x86/hyperv: Disable IBT when hypercall page lacks ENDBR instruction Date: Fri, 21 Jul 2023 21:51:16 -0700 Message-Id: <1690001476-98594-1-git-send-email-mikelley@microsoft.com> X-Mailer: git-send-email 1.8.3.1 Content-Type: text/plain X-ClientProxiedBy: MW4PR04CA0265.namprd04.prod.outlook.com (2603:10b6:303:88::30) To DM6PR21MB1370.namprd21.prod.outlook.com (2603:10b6:5:16b::28) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM6PR21MB1370:EE_|DM4PR21MB3416:EE_ X-MS-Office365-Filtering-Correlation-Id: 5070e73b-f46a-4c03-b1e1-08db8a6f568b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM6PR21MB1370.namprd21.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230028)(4636009)(346002)(39860400002)(396003)(366004)(136003)(376002)(451199021)(66556008)(66946007)(4326008)(66476007)(7416002)(5660300002)(41300700001)(2906002)(316002)(6486002)(52116002)(2616005)(6506007)(8676002)(8936002)(186003)(26005)(82950400001)(82960400001)(38100700002)(38350700002)(921005)(86362001)(6512007)(10290500003)(478600001)(6666004)(36756003);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?CbZWIdROjWxoC94r86d+Gic2yPAS0W3VE0jaHSm8fkfq9pp5gHeLeqGqg/Ad?= =?us-ascii?Q?hz5l7rxFPXGPfCb0igKn5xvQlxcLbLOYssx9LrpfVd4qPcONVbf573lX6tZX?= =?us-ascii?Q?peOAfX6QLCWQs4R7ktrCRJH/9glPWhPrUEVNn7HNBr/sbpe2An5yrgEFZPpa?= =?us-ascii?Q?q5MeXm5tTHMfc1ZPphOYzZzxtkTpkKu+CEax/Tj4/l1bcY2BhdQyVkIZknv9?= =?us-ascii?Q?JI7mxuOuuHBoBKFYM3f7kcp+Rp8dxIZEhAgTKEfp5JojfXBMkMiFTURH5CvS?= =?us-ascii?Q?pTKMUvn0fsFGm2T/WCXKOAxmOQEOxlP57+yMY0+pHn8bVkUawWYSl+yqeeTo?= =?us-ascii?Q?Xx0GDHgWIfUz8hHuC0LjhwSeAHxE9N8pRX7l/vJpHG/AEyRQlNEcrR+MRQ+J?= =?us-ascii?Q?jPYPZ7kBYN0wVWI+TakiRvZwnj0BUdD5pwPqBfO5hVnmzJtQUr/p5qGfnCXY?= =?us-ascii?Q?EnimBmzBTNuWZKhHEePyqibpaTMt5j8HioU4PF1rbNWZL9ubNpaBeBW8wOd8?= =?us-ascii?Q?K91b031FpqKRFsWauXYSZlKJXEbNoOu8tMTx90tXXYG0AkGkeY9cSpGmlA4/?= =?us-ascii?Q?U70A8mDNxyiNMkCG1uTKyqBzdMeOGrgh/1CtKGYZxLIiAG38XH8G6UQk4q7s?= =?us-ascii?Q?7udu+dJCVrRYgefV8pGejXzG58dhA7XvfsQrxrg8Z5W1+yEd71i5WkdVEaoS?= =?us-ascii?Q?KUT5IzwJoWUaXQuwGkFWx38VjYceWryAQFNBHD2bzMee/1HJ2Y07TU/Y32Ti?= =?us-ascii?Q?JjKyjxg3pbs2pQq8MzU7jR79dJvjsYk4T9Rid1ZSUzkW3hCiF5aN+GbIB96S?= =?us-ascii?Q?3wSSU6ERRWlwHW7l20WKD/wwl0+BSgbkzzFTTnEslZEev85w0OGLZnUAGPLx?= =?us-ascii?Q?KgSZQZOdkEetAB8BmpiK4mOHZolqGNGUgjFYIw6Ps60YoEKV5VJk7DJSW8Fd?= =?us-ascii?Q?hkxpAHaZOQ5MxT5e+Cr2tuGqGDgF6vYfzVrHdF/h+rNMu+vT3L+8omML9YAp?= =?us-ascii?Q?AmLQzTiqNYa88WZxD1/mLQN2247CJHJaPfUy8xam27EzmLC85de8OcEdFlK7?= =?us-ascii?Q?/d095QyFD8KQRPzaYoOOHPunLTTamY2SW2XkgOGKWeiw98wYjKJKEshSLA69?= =?us-ascii?Q?Dwg49/aChK/g/LC+2gNvGGghqk+v9BD4UYZWVvWsuuhSo+kbYhRRE6H/bRcX?= =?us-ascii?Q?/Dx27VQgQMIFkx+ZOjthrRdg9E7VVVpNQNHBvYBZ2ouYIPEWv7Mg8U0xt61w?= =?us-ascii?Q?VuQGO7F2SLl6YNtod5ZLHIHqpMsJ3Ad8ZjS35GEIt3LaSf3Ugp8ho+GmoOjV?= =?us-ascii?Q?lsq61S7HEV2lYc7D/gPAyOU4xAAXNpEoPIO21lQcLjia8jrw9EgRJOha2pyS?= =?us-ascii?Q?J9xJ4voi2/NZx9kmL0pDg+Cj8BiDXuBQ3JtdimAYbScFudTsjZHjTwCmxMsR?= =?us-ascii?Q?uUTTwkJXMIQnGvluYYEvJurOtLFCnpYuvSJUi9e5ChsJKK8d38g3cGBwj/FB?= =?us-ascii?Q?ztSGdwqRpbe8gRbqDkkV+0b1t+IRq/rbjQt7XmZdZO0IhqWmZmYDmEU2kAOV?= =?us-ascii?Q?mSRyDjAZLpmzckayTE+QvVGnf70W8e4YyeV9rhN8?= X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5070e73b-f46a-4c03-b1e1-08db8a6f568b X-MS-Exchange-CrossTenant-AuthSource: DM6PR21MB1370.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Jul 2023 04:51:40.1926 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: QGQ8Loj0foU59Ol2ERTxvhNjuha/NJuV6nClBtx9tWcgDjDh5YC2ykt+2JNoDaAqS1OVls88aXe9beY/n7PxkQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR21MB3416 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On hardware that supports Indirect Branch Tracking (IBT), Hyper-V VMs with ConfigVersion 9.3 or later support IBT in the guest. However, current versions of Hyper-V have a bug in that there's not an ENDBR64 instruction at the beginning of the hypercall page. Since hypercalls are made with an indirect call to the hypercall page, all hypercall attempts fail with an exception and Linux panics. A Hyper-V fix is in progress to add ENDBR64. But guard against the Linux panic by clearing X86_FEATURE_IBT if the hypercall page doesn't start with ENDBR. The VM will boot and run without IBT. If future Linux 32-bit kernels were to support IBT, additional hypercall page hackery would be needed to make IBT work for such kernels in a Hyper-V VM. Cc: stable@vger.kernel.org Signed-off-by: Michael Kelley --- Changes in v2: * Use pr_warn() instead of pr_info() [Peter Zijlstra] arch/x86/hyperv/hv_init.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 6c04b52..5cbee24 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -472,6 +473,26 @@ void __init hyperv_init(void) } /* + * Some versions of Hyper-V that provide IBT in guest VMs have a bug + * in that there's no ENDBR64 instruction at the entry to the + * hypercall page. Because hypercalls are invoked via an indirect call + * to the hypercall page, all hypercall attempts fail when IBT is + * enabled, and Linux panics. For such buggy versions, disable IBT. + * + * Fixed versions of Hyper-V always provide ENDBR64 on the hypercall + * page, so if future Linux kernel versions enable IBT for 32-bit + * builds, additional hypercall page hackery will be required here + * to provide an ENDBR32. + */ +#ifdef CONFIG_X86_KERNEL_IBT + if (cpu_feature_enabled(X86_FEATURE_IBT) && + *(u32 *)hv_hypercall_pg != gen_endbr()) { + setup_clear_cpu_cap(X86_FEATURE_IBT); + pr_warn("Hyper-V: Disabling IBT because of Hyper-V bug\n"); + } +#endif + + /* * hyperv_init() is called before LAPIC is initialized: see * apic_intr_mode_init() -> x86_platform.apic_post_init() and * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER -- 1.8.3.1