From nobody Sat Oct 4 21:02:24 2025 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.14]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0BC60291861 for ; Wed, 13 Aug 2025 17:27:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.14 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755106038; cv=none; b=cmYDkGGobtBpTUiFaNcQTQ8ZHg+StIZd67kcaXUSYElP5uxWiGXMbdtUq9L5O1azR/v3UUfyuhN2QFdxg20LUwzm85jR9p+YTNmo/s3SqCqZs9m4cxVp2L83hSjtIRTjawzuN5PyMHzsMuplen4sFXZatgn634UdjoWhuXaZfbY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755106038; c=relaxed/simple; bh=xpbDvW/BHKIgitRmU6XLqWtAPgxiXoMaMAxkxFpaLt4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=B02QlSs9ZJxLxPUeRqIA4TTTeuqvCS+oCdxAw4LfPl/Gn/MXxJLhoMiC7bUrQJQE1UKzN9TzqTTu/63uCfw/48nrAdTzRfABMTIHbQ/m35ItIkMPPp/Rii9Usj1KWic1SnGedDQtj5l+ZYdqtn1B7Kt2ocK5pY+ezA+ihmFQ91E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=NNkyqL2l; arc=none smtp.client-ip=198.175.65.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="NNkyqL2l" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1755106038; x=1786642038; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=xpbDvW/BHKIgitRmU6XLqWtAPgxiXoMaMAxkxFpaLt4=; b=NNkyqL2lxFIZ8LHRFYphtRv3WcfXtbDU2kZz3yZMyxXjB7aEJO5+sy2/ 77KCfUzjcsI+9sJt3InNEfKFiH3JBkHnIhpDbmKaUojCj+zNXIuAeYIdZ 84g07x+YzOld4DanjsZYbBAMHb93kxqzSoqo4qwbPE18GDVjFGj0EpIOj A43CAbJZaOYvhu8qHIXKRmgsIkEc6KQqeGDMq7d0WyU6/YHGlkRCYcXHT 3s7MxknPeBYTlgPMj0Q7M7bVeFlxNCHi5QLQg1ZYM3lw9ZpyP3BiY9t58 eExH984umj0HPU72e5nwzcVUYeuSHZVgTx3ESyJyHpylTGv386DLZwjRN g==; X-CSE-ConnectionGUID: hMam2lQYQw+RFgicembvUA== X-CSE-MsgGUID: Mg2sn0RiTnujlq8yNXdiTA== X-IronPort-AV: E=McAfee;i="6800,10657,11520"; a="61255261" X-IronPort-AV: E=Sophos;i="6.17,287,1747724400"; d="scan'208";a="61255261" Received: from fmviesa010.fm.intel.com ([10.60.135.150]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Aug 2025 10:27:17 -0700 X-CSE-ConnectionGUID: FHour4/+Q66Jz3QbIqYJBA== X-CSE-MsgGUID: oe/4pfVxSryXDOtdndcCNw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,287,1747724400"; d="scan'208";a="167329719" Received: from cbae1-mobl.amr.corp.intel.com (HELO cbae1-mobl.intel.com) ([10.124.161.193]) by fmviesa010.fm.intel.com with ESMTP; 13 Aug 2025 10:27:16 -0700 From: "Chang S. Bae" To: x86@kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, colinmitchell@google.com, chao.gao@intel.com, abusse@amazon.de, chang.seok.bae@intel.com, linux-kernel@vger.kernel.org Subject: [PATCH v4 6/6] x86/microcode/intel: Enable staging when available Date: Wed, 13 Aug 2025 10:26:49 -0700 Message-ID: <20250813172649.15474-7-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250813172649.15474-1-chang.seok.bae@intel.com> References: <20250409232713.4536-1-chang.seok.bae@intel.com> <20250813172649.15474-1-chang.seok.bae@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" With the staging code being ready, check for staging availability by reading these following MSRs: * IA32_ARCH_CAPABILITIES (bit 16) for the presence of IA32_MCU_ENUMERATION * IA32_MCU_ENUMERATION (bit 4) for the staging feature availability. When available, enable it by setting the feature bit. Signed-off-by: Chang S. Bae Tested-by: Anselm Busse Reviewed-by: Chao Gao --- V1 -> V2: Fold MSR definings (Boris). --- arch/x86/include/asm/msr-index.h | 7 +++++++ arch/x86/kernel/cpu/microcode/intel.c | 17 +++++++++++++++++ 2 files changed, 24 insertions(+) diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-in= dex.h index 0356155f9264..2b7b598c414f 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -166,6 +166,10 @@ * Processor MMIO stale data * vulnerabilities. */ +#define ARCH_CAP_MCU_ENUM BIT(16) /* + * Indicates the presence of microcode update + * feature enumeration and status information + */ #define ARCH_CAP_FB_CLEAR BIT(17) /* * VERW clears CPU fill buffer * even on MDS_NO CPUs. @@ -913,6 +917,9 @@ #define MSR_IA32_UCODE_WRITE 0x00000079 #define MSR_IA32_UCODE_REV 0x0000008b =20 +#define MSR_IA32_MCU_ENUMERATION 0x0000007b +#define MCU_STAGING BIT(4) + #define MSR_IA32_MCU_STAGING_MBOX_ADDR 0x000007a5 =20 /* Intel SGX Launch Enclave Public Key Hash MSRs */ diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/mi= crocode/intel.c index 5402bcb96f47..4da5f3581a94 100644 --- a/arch/x86/kernel/cpu/microcode/intel.c +++ b/arch/x86/kernel/cpu/microcode/intel.c @@ -959,6 +959,18 @@ static __init void calc_llc_size_per_core(struct cpuin= fo_x86 *c) llc_size_per_core =3D (unsigned int)llc_size; } =20 +static __init bool staging_available(void) +{ + u64 val; + + val =3D x86_read_arch_cap_msr(); + if (!(val & ARCH_CAP_MCU_ENUM)) + return false; + + rdmsrl(MSR_IA32_MCU_ENUMERATION, val); + return !!(val & MCU_STAGING); +} + struct microcode_ops * __init init_intel_microcode(void) { struct cpuinfo_x86 *c =3D &boot_cpu_data; @@ -969,6 +981,11 @@ struct microcode_ops * __init init_intel_microcode(voi= d) return NULL; } =20 + if (staging_available()) { + microcode_intel_ops.use_staging =3D true; + pr_info("Enabled staging feature.\n"); + } + calc_llc_size_per_core(c); =20 return µcode_intel_ops; --=20 2.48.1