From nobody Fri Sep 19 03:44:28 2025 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 426A8C4332F for ; Tue, 29 Nov 2022 21:09:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236852AbiK2VJl (ORCPT ); Tue, 29 Nov 2022 16:09:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233743AbiK2VJH (ORCPT ); Tue, 29 Nov 2022 16:09:07 -0500 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A631EE32 for ; Tue, 29 Nov 2022 13:09:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1669756145; x=1701292145; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=+c+idxLi34QmYjm2JNwF3yjYRC3bi0/GYB7hm+1xYXc=; b=iMSjoF5xPeqZPvkk5bmJPC5ioZnaWGMJrbWs0aE7KSglJw2rXcjz7VWA sFmUlpEvTYDEzYzpEByAftwRjKxEjIwjRVWwF1zrXDHKrEvoDhLvQng5y KwiTAt7JxI19NQpRqhefjZN0j1VJym7xSRDwjQ0GD94Fd45TuwuKIlzng svXp6theL+SkbbBH13Cnf7afNdtzuMwNcnUe2ttvuAzvbT8F+i0Yf15sA nmSashcbh+93ZOq1rICl+VtDh35lF9yU5UcyIH7DjbrcCtO/kmBjrsK+t RUfIRY4AphpGlWT9/GEboYVT+Pd2+ErxPHeMZrjPnQa6bXuMhgEmWua5/ Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10546"; a="317083139" X-IronPort-AV: E=Sophos;i="5.96,204,1665471600"; d="scan'208";a="317083139" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Nov 2022 13:09:04 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10546"; a="646066211" X-IronPort-AV: E=Sophos;i="5.96,204,1665471600"; d="scan'208";a="646066211" Received: from araj-ucode.jf.intel.com ([10.23.0.19]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Nov 2022 13:09:04 -0800 From: Ashok Raj To: Borislav Petkov Cc: X86-kernel , LKML Mailing List , Ashok Raj , Dave Hansen , Tony Luck , alison.schofield@intel.com, reinette.chatre@intel.com Subject: [Patch V1 4/7] x86/microcode/core: Take a snapshot before and after applying microcode Date: Tue, 29 Nov 2022 13:08:29 -0800 Message-Id: <20221129210832.107850-5-ashok.raj@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221129210832.107850-1-ashok.raj@intel.com> References: <20221129210832.107850-1-ashok.raj@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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. 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 Reviewed-by: Tony Luck --- arch/x86/kernel/cpu/microcode/core.c | 36 ++++++++++++++++++++-------- 1 file changed, 26 insertions(+), 10 deletions(-) diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/mic= rocode/core.c index ef24e1d228d0..fab2010ff368 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -431,12 +431,28 @@ static int __reload_late(void *info) return ret; } =20 +static void copy_cpu_caps(struct cpuinfo_x86 *info) +{ + /* Reload CPUID max function as it might've changed. */ + info->cpuid_level =3D 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 fea= tures, * only when microcode has been updated. Caller holds microcode_mutex and = CPU * hotplug lock. */ -static void microcode_check(void) +static void microcode_check(struct cpuinfo_x86 *orig) { struct cpuinfo_x86 info; =20 @@ -446,15 +462,13 @@ static void microcode_check(void) info.cpuid_level =3D cpuid_eax(0); =20 /* - * 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.x= 86_capability)); + * 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(). + */ + copy_cpu_caps(&info); =20 - get_cpu_cap(&info); - - if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability, + if (!memcmp(&info.x86_capability, &orig->x86_capability, sizeof(info.x86_capability))) return; =20 @@ -469,6 +483,7 @@ static void microcode_check(void) static int microcode_reload_late(void) { int old =3D boot_cpu_data.microcode, ret; + struct cpuinfo_x86 info; =20 pr_err("Attempting late microcode loading - it is dangerous and taints th= e kernel.\n"); pr_err("You should switch to early loading, if possible.\n"); @@ -476,9 +491,10 @@ static int microcode_reload_late(void) atomic_set(&late_cpus_in, 0); atomic_set(&late_cpus_out, 0); =20 + copy_cpu_caps(&info); ret =3D stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask); if (ret =3D=3D 0) - microcode_check(); + microcode_check(&info); =20 pr_info("Reload completed, microcode revision: 0x%x -> 0x%x\n", old, boot_cpu_data.microcode); --=20 2.34.1