From patchwork Tue Dec 5 10:50:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Li, Xin3" X-Patchwork-Id: 13480006 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="QIRaaP4a" Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4D3A1B3; Tue, 5 Dec 2023 03:21:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1701775293; x=1733311293; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=9l8F1WmhlJ7jRL54JQMm6v1HYP6GXYsOB2qRuf6ZAIU=; b=QIRaaP4ai5nU0yfEW7NPpKlu303fM6X7aecv/i6NhDYravKCctIv55lE FO/Gcu5T/LeC80K53qiG8I07J4H/+ZbebLSaybD0VVEiz+YI6gCdkplkZ h9iRXiXqjape/Nn2kIurZ0t6VAqzncA/tQba3nn7CbXDjG8p6/DJi6u5J dKaGOfoY0aFq0ok5QlprrGSYQqQRIQNDNNDpyE8HFN8uSFQKL/hyJqwhH SqbWhw8FnWzSypeC7l42SB6N2O5EGPXBLK8rvPOvhGIKNnjy94X5Q4gLL KmlVMbvUSPwOFXScPdRN/z2+W4oFNTvsnJE82WgRo2VTMwhMBewL51Ceg w==; X-IronPort-AV: E=McAfee;i="6600,9927,10914"; a="942607" X-IronPort-AV: E=Sophos;i="6.04,252,1695711600"; d="scan'208";a="942607" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Dec 2023 03:21:25 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10914"; a="1018192988" X-IronPort-AV: E=Sophos;i="6.04,252,1695711600"; d="scan'208";a="1018192988" Received: from unknown (HELO fred..) ([172.25.112.68]) by fmsmga006.fm.intel.com with ESMTP; 05 Dec 2023 03:21:23 -0800 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, shan.kang@intel.com Subject: [PATCH v13 25/35] x86/fred: Add a machine check entry stub for FRED Date: Tue, 5 Dec 2023 02:50:14 -0800 Message-ID: <20231205105030.8698-26-xin3.li@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231205105030.8698-1-xin3.li@intel.com> References: <20231205105030.8698-1-xin3.li@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 1642018dd6c9..d524eb87f76c 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -53,6 +53,7 @@ #include #include #include +#include #include "internal.h" @@ -2150,6 +2151,31 @@ 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)