From patchwork Tue Oct 3 06:24:48 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Li, Xin3" X-Patchwork-Id: 13406861 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 CE8CDE75428 for ; Tue, 3 Oct 2023 06:57:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239303AbjJCG5u (ORCPT ); Tue, 3 Oct 2023 02:57:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239522AbjJCG5l (ORCPT ); Tue, 3 Oct 2023 02:57:41 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 19132AD; Mon, 2 Oct 2023 23:55:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1696316129; x=1727852129; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=bNtEfhEic2/4eI6U3F6LZD3GtdQN7TZ08d/4AOd+L9I=; b=Yi/z7nBMIQmwh6m0Mc7MSjp6xVnaZzSN2N9HdApVBXN7+GJYt5tOUB1f 892EA2jb/fEAdRe/MrP2c+p606IPGKwZ0jD8RP2AC728YzjtAr+3HFG71 WMhKimaz7a7SOfxqwpxKzmhUtfWnVVLcN5N4YD77O0uG6yfOS2VcXUQTW tZ+reDa8CcAzMd/uy2DNOPEZIKehddWSu+vPi4alm7jXoQlOyJ3iZ+Wje diFANd6wKgix7mtr/5gXIusL8zvrRTJcP2GWroiBqneKUoH8Wsl0/ySDJ Enp8uMrVpr6aJcrE66No58N5OzebtdnA7X68swasH3WI1gDCydZTIY/Ej w==; X-IronPort-AV: E=McAfee;i="6600,9927,10851"; a="367858241" X-IronPort-AV: E=Sophos;i="6.03,196,1694761200"; d="scan'208";a="367858241" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Oct 2023 23:54:48 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10851"; a="1081900986" X-IronPort-AV: E=Sophos;i="6.03,196,1694761200"; d="scan'208";a="1081900986" Received: from unknown (HELO fred..) ([172.25.112.68]) by fmsmga005.fm.intel.com with ESMTP; 02 Oct 2023 23:54:48 -0700 From: Xin Li To: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, pbonzini@redhat.com, seanjc@google.com, peterz@infradead.org, jgross@suse.com, ravi.v.shankar@intel.com, mhiramat@kernel.org, andrew.cooper3@citrix.com, jiangshanlai@gmail.com, nik.borisov@suse.com Subject: [PATCH v12 27/37] x86/fred: Add a machine check entry stub for FRED Date: Mon, 2 Oct 2023 23:24:48 -0700 Message-Id: <20231003062458.23552-28-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231003062458.23552-1-xin3.li@intel.com> References: <20231003062458.23552-1-xin3.li@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Like #DB, when occurred on different ring level, i.e., from user or kernel context, #MCE needs to be handled on different stack: User #MCE on current task stack, while kernel #MCE on a dedicated stack. This is exactly how FRED event delivery invokes an exception handler: ring 3 event on level 0 stack, i.e., current task stack; ring 0 event on the #MCE dedicated stack specified in the IA32_FRED_STKLVLS MSR. So unlike IDT, the FRED machine check entry stub doesn't do stack switch. Tested-by: Shan Kang Signed-off-by: Xin Li --- Changes since v5: * Disallow #DB inside #MCE for robustness sake (Peter Zijlstra). --- arch/x86/kernel/cpu/mce/core.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 6f35f724cc14..da0a4a102afe 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -52,6 +52,7 @@ #include #include #include +#include #include "internal.h" @@ -2144,6 +2145,31 @@ DEFINE_IDTENTRY_MCE_USER(exc_machine_check) exc_machine_check_user(regs); local_db_restore(dr7); } + +#ifdef CONFIG_X86_FRED +/* + * When occurred on different ring level, i.e., from user or kernel + * context, #MCE needs to be handled on different stack: User #MCE + * on current task stack, while kernel #MCE on a dedicated stack. + * + * This is exactly how FRED event delivery invokes an exception + * handler: ring 3 event on level 0 stack, i.e., current task stack; + * ring 0 event on the #MCE dedicated stack specified in the + * IA32_FRED_STKLVLS MSR. So unlike IDT, the FRED machine check entry + * stub doesn't do stack switch. + */ +DEFINE_FREDENTRY_MCE(exc_machine_check) +{ + unsigned long dr7; + + dr7 = local_db_save(); + if (user_mode(regs)) + exc_machine_check_user(regs); + else + exc_machine_check_kernel(regs); + local_db_restore(dr7); +} +#endif #else /* 32bit unified entry point */ DEFINE_IDTENTRY_RAW(exc_machine_check)