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[2620:137:e000::1:20]) by mx.google.com with ESMTP id y14-20020a056402270e00b0046154884604si13855965edd.482.2022.12.27.14.24.00; Tue, 27 Dec 2022 14:24:16 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=mOgBGnjQ; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232026AbiL0VJI (ORCPT + 66 others); Tue, 27 Dec 2022 16:09:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46268 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231723AbiL0VIO (ORCPT ); Tue, 27 Dec 2022 16:08:14 -0500 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6454CDF52 for ; Tue, 27 Dec 2022 13:02:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1672174925; x=1703710925; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=phiqAvz/xpITFJnL47O2QLXJB8ncqn7f9MVajt9NJVM=; b=mOgBGnjQ9QQm6SYao/YIz0CJ4Pqby68iH9ZaSXYcmOc5aGoWJluqY/53 o/TpU2i8FtcUfx0WZgH7Df4qIzdgVApqgJS9dYat4+qspCsnVi7ljiVP/ 1729vNO8OsrRLGHSFlSz2Til3W1o4zMAB9IWQR7Sl3Nt3kMtW6HmbDmU2 z1tYWghH7x1qVT156RFj1cr7+f6+pWSh5Im/p3/bOIIq+BPZGhv33SVFM 590wR0jP7N9pRm+MK3yqdjCp5JJCGy/KcBXRLKtUHU8ufwMAq+e2Sj7xH qAq/ylauo110bmYpqXqXaAUMXROfJq+JmzJ32KzbNHgSQcVGWrqN3B1es Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10573"; a="304259686" X-IronPort-AV: E=Sophos;i="5.96,279,1665471600"; d="scan'208";a="304259686" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Dec 2022 13:02:03 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10573"; a="760435297" X-IronPort-AV: E=Sophos;i="5.96,279,1665471600"; d="scan'208";a="760435297" Received: from araj-ucode.jf.intel.com ([10.23.0.19]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Dec 2022 13:02:01 -0800 From: Ashok Raj To: Borislav Petkov , Thomas Gleixner Cc: X86-kernel , LKML Mailing List , Ashok Raj , Dave Hansen , Tony Luck , Alison Schofield , Reinette Chatre , Tom Lendacky Subject: [PATCH v3 2/2] x86/microcode/core: Take a snapshot before and after applying microcode Date: Tue, 27 Dec 2022 13:01:44 -0800 Message-Id: <20221227210144.5112-2-ashok.raj@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE, SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The kernel caches features about each CPU's features at boot in an x86_capability[] structure. The microcode update takes one snapshot and compares it with the saved copy at boot. However, the capabilities in the boot copy can be turned off as a result of certain command line parameters or configuration restrictions. This can cause a mismatch when comparing the values before and after the microcode update. microcode_check() is called after an update to report any previously cached CPUID bits might have changed due to the update. microcode_store_cpu_caps() basically stores the original CPU reported values and not the OS modified values. This will avoid giving a false warning even if no capabilities have changed. Ignore the capabilities recorded at boot. Take a new snapshot before the update and compare with a snapshot after the update to eliminate the false warning. Fixes: 1008c52c09dc ("x86/CPU: Add a microcode loader callback") Signed-off-by: Ashok Raj Cc: LKML Cc: x86 Cc: Tony Luck Cc: Dave Hansen Cc: Alison Schofield Cc: Reinette Chatre Cc: Thomas Gleixner Cc: Tom Lendacky --- Changes since last post - Boris - Change function from copy_cpu_caps() -> store_cpu_caps() - Keep microcode_check() inside cpu/common.c and not bleed get_cpu_caps() outside of core code. - Thomas : Commit log changes. --- arch/x86/include/asm/processor.h | 1 + arch/x86/kernel/cpu/common.c | 17 +++++++++++++++++ arch/x86/kernel/cpu/microcode/core.c | 7 +++++++ 3 files changed, 25 insertions(+) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 387578049de0..ac2e67156b9b 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -697,6 +697,7 @@ bool xen_set_default_idle(void); #endif void __noreturn stop_this_cpu(void *dummy); +void microcode_store_cpu_caps(struct cpuinfo_x86 *info); void microcode_check(struct cpuinfo_x86 *info); enum l1tf_mitigations { diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index b9c7529c920e..1f0b57a5d89d 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2297,6 +2297,23 @@ void cpu_init_secondary(void) #endif #ifdef CONFIG_MICROCODE_LATE_LOADING + +void microcode_store_cpu_caps(struct cpuinfo_x86 *info) +{ + /* Reload CPUID max function as it might've changed. */ + info->cpuid_level = cpuid_eax(0); + + /* + * Copy all capability leafs to pick up the synthetic ones so that + * memcmp() below doesn't fail on that. The ones coming from CPUID will + * get overwritten in get_cpu_cap(). + */ + memcpy(info->x86_capability, &boot_cpu_data.x86_capability, + sizeof(info->x86_capability)); + + get_cpu_cap(info); +} + /* * The microcode loader calls this upon late microcode load to recheck features, * only when microcode has been updated. Caller holds microcode_mutex and CPU diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index d86a4f910a6b..14d9031ed68a 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -447,6 +447,13 @@ static int microcode_reload_late(void) atomic_set(&late_cpus_in, 0); atomic_set(&late_cpus_out, 0); + /* + * Take a snapshot before the microcode update, so we can compare + * them after the update is successful to check for any bits + * changed. + */ + microcode_store_cpu_caps(&info); + ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask); if (ret == 0) microcode_check(&info); -- 2.34.1