From nobody Sat Oct 4 12:49:03 2025 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) (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 18EED2797AC; Mon, 18 Aug 2025 07:14:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.13 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755501249; cv=none; b=OE8U91s2lqTtWa7LpZQ8k6mZJi/+URUyKABQbMCFuzQ6p2nPXt/y28nA6ShZiBAI+pNfoWrRMf/Lxyq1vqlYh/wLuyexEHVYEnREm6/mA7JvVAmx6niBCxaY7FE5+lw8ni1oBCuk4USxYtNknC3Uv+UG/Gojp2KtZShisouqd0E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755501249; c=relaxed/simple; bh=vOJ2GKotCBT/sq8+HRU47E6S57fE3G/dySeV4dTwl84=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Y35Qw80JauCP4xJO8BEam3M7zIu7I1OuJiEZ1I13eSJ293jYOdRFeXqhAJ4gbg3JS554xcq87Qfr6HUgkLdi+6vUha0E1OOXp3Fz84jYWdKHayVwkplmgBncSnToMqdCITXJ0Dkvo7999nFB9tQ6tS7kKOSW7WCBVDDeVuxUH1s= 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=i8zs/TIP; arc=none smtp.client-ip=198.175.65.13 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="i8zs/TIP" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1755501248; x=1787037248; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=vOJ2GKotCBT/sq8+HRU47E6S57fE3G/dySeV4dTwl84=; b=i8zs/TIPdhRaNQN7ZZdo2VlSB5mQKK5YSIajCUT3h8ic3XMpk5NJ/dmh b8EawX0jSDpr4clL4/5Ezo4QELrvToWc9EbnPMztFbOnmfUCNg8+aA8lp wzYbX5fIgFEfxQfgNpEioWXUvPsV4MKrG+Xd6q+LMBYXrZChZ5ztAneV4 pUZmhdwq180xcmsPVQOWQ9IatXUzMsXmjMeP92dOfUyASyB+j6sI3ZNYO MnZwok8PCU9+nQAl8mWUeXqmVUUxjb30TFzqALNpG7FC9dgM42948cpyY S2CLIN9pm00qodu/JMX9yFryJTYe4iUFoSUhj3KGMpkeEdYY3IIaMxXlz A==; X-CSE-ConnectionGUID: Kr2ieCaIQMehbLYlJYGq5A== X-CSE-MsgGUID: WrIOB6XwSi+BDAVwh7lrxw== X-IronPort-AV: E=McAfee;i="6800,10657,11524"; a="68809430" X-IronPort-AV: E=Sophos;i="6.17,293,1747724400"; d="scan'208";a="68809430" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2025 00:14:08 -0700 X-CSE-ConnectionGUID: kbfNj9XkRE28MbyAYqbmAQ== X-CSE-MsgGUID: Hqj9i+zuSzu6hOtocH/xUA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,293,1747724400"; d="scan'208";a="167421532" Received: from opintica-mobl1 (HELO eresheto-mobl3.ger.corp.intel.com) ([10.245.245.174]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2025 00:13:52 -0700 From: Elena Reshetova To: dave.hansen@intel.com Cc: jarkko@kernel.org, seanjc@google.com, kai.huang@intel.com, mingo@kernel.org, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, asit.k.mallick@intel.com, vincent.r.scarlata@intel.com, chongc@google.com, erdemaktas@google.com, vannapurve@google.com, bondarn@google.com, scott.raynor@intel.com, Elena Reshetova Subject: [PATCH v15 5/5] x86/sgx: Enable automatic SVN updates for SGX enclaves Date: Mon, 18 Aug 2025 10:11:23 +0300 Message-ID: <20250818071304.1717183-6-elena.reshetova@intel.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250818071304.1717183-1-elena.reshetova@intel.com> References: <20250818071304.1717183-1-elena.reshetova@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable =3D=3D Background =3D=3D ENCLS[EUPDATESVN] is a new SGX instruction [1] which allows enclave attestation to include information about updated microcode SVN without a reboot. Before an EUPDATESVN operation can be successful, all SGX memory (aka. EPC) must be marked as =E2=80=9Cunused=E2=80=9D in the SGX hardware m= etadata (aka.EPCM). This requirement ensures that no compromised enclave can survive the EUPDATESVN procedure and provides an opportunity to generate new cryptographic assets. =3D=3D Solution =3D=3D Attempt to execute ENCLS[EUPDATESVN] every time the first file descriptor is obtained via sgx_(vepc_)open(). In the most common case the microcode SVN is already up-to-date, and the operation succeeds without updating SVN. Note: while in such cases the underlying crypto assets are regenerated, it does not affect enclaves' visible keys obtained via EGETKEY instruction. If it fails with any other error code than SGX_INSUFFICIENT_ENTROPY, this is considered unexpected and the *open() returns an error. This should not happen in practice. On contrary, SGX_INSUFFICIENT_ENTROPY might happen due to a pressure on the system's DRNG (RDSEED) and therefore the *open() can be safely retried to allow normal enclave operation. [1] Runtime Microcode Updates with Intel Software Guard Extensions, https://cdrdv2.intel.com/v1/dl/getContent/648682 Reviewed-by: Kai Huang Reviewed-by: Jarkko Sakkinen Signed-off-by: Elena Reshetova --- arch/x86/kernel/cpu/sgx/main.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index ffc7b9496218..3eda7e7942e6 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -934,7 +934,7 @@ static int sgx_usage_count; * * entropy in RNG * * %-EIO: - Unexpected error, retries are not advisable */ -static int __maybe_unused sgx_update_svn(void) +static int sgx_update_svn(void) { int ret; =20 @@ -992,14 +992,30 @@ static int __maybe_unused sgx_update_svn(void) return -EIO; } =20 +/* Mutex to ensure no concurrent EPC accesses during EUPDATESVN */ +static DEFINE_MUTEX(sgx_svn_lock); + int sgx_inc_usage_count(void) { + int ret; + + guard(mutex)(&sgx_svn_lock); + + if (!sgx_usage_count) { + ret =3D sgx_update_svn(); + if (ret) + return ret; + } + + sgx_usage_count++; + return 0; } =20 void sgx_dec_usage_count(void) { - return; + guard(mutex)(&sgx_svn_lock); + sgx_usage_count--; } =20 static int __init sgx_init(void) --=20 2.45.2