From nobody Mon Oct 6 08:25:35 2025 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.10]) (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 DD437275103; Thu, 24 Jul 2025 08:04:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.10 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753344243; cv=none; b=c6a8CXgB/n6J2ggOlmdMWoCj2qQjnz3SRlalaxMkeyhw6HpTCKtpoUy64U/z/6oxdVj0giSHkBW4GBT4g/6+M++0H+eVrDtE8qvP5mD3XKdi8sWTOHMkEJOJSgsJRS9z93RjGA3JE/FFF5shdf3/hXw6ELuc7OPsjSISf7w+WqE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753344243; c=relaxed/simple; bh=hJ78VH6KfiP/kPVA/V86syXh1HmFRiQnUtKrsFN/w9s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=lMbnyg2WtlnKNh8sTHBNdAB+/zy7OB9afdqkjTNsUgrMy8FVMc/dBqYPU1tyK0UCTD/E8k6k0xXfEqAHfIx0Ox3C92yT1N69NJIH36bM4rXBYVOvSPtiTkbSMksCwNu6BORFY86ZGAQXbpAcWhxp9sc+5HPFuAMkWjvPAirK1h0= 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=khMPqsSL; arc=none smtp.client-ip=192.198.163.10 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="khMPqsSL" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1753344242; x=1784880242; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=hJ78VH6KfiP/kPVA/V86syXh1HmFRiQnUtKrsFN/w9s=; b=khMPqsSLPcCD++WjGBRiMN+QYzUUtwDAFelR/TUHSxJlaQKI9ECw3OGz QnAmohTUtnbqOBpWKi+inv2nVP7DhWXF4NB/Mv9TDUAL7MBxDjebDshMx KYetdPNx3Og16YUXBMbRS7Xduw2+9LwgaL+FLrhNRCCvA0qDs+4hXJ04s 1NNBVNbhGpqVAQgK6VPpgjKi3nFt7XloHhmAH7LdOmHg4sYf3KkkCIjFT Unpnrp/gX307ppSVst4u6HI7LIkfBY5VYa80eJW8QxTN5SY9t4YILTv/s SRwidJj6knrgnPsDx6qIXuXdTqMZos8huHNr6fU44FgqZ88a6m8rXNXC6 Q==; X-CSE-ConnectionGUID: a7bjVq1uRReqThIW9LiJ6A== X-CSE-MsgGUID: E6pCpRoDRXitxITK2nSvVg== X-IronPort-AV: E=McAfee;i="6800,10657,11501"; a="66992002" X-IronPort-AV: E=Sophos;i="6.16,336,1744095600"; d="scan'208";a="66992002" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jul 2025 01:04:02 -0700 X-CSE-ConnectionGUID: gQyNVfTXRTSLHfVeYXAguQ== X-CSE-MsgGUID: t20ShfOwRKCo6p1uKacpxA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,336,1744095600"; d="scan'208";a="160342242" Received: from savramon-mobl1 (HELO eresheto-mobl3.ger.corp.intel.com) ([10.245.244.60]) by fmviesa009-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jul 2025 01:03:57 -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 v9 6/6] x86/sgx: Enable automatic SVN updates for SGX enclaves Date: Thu, 24 Jul 2025 11:02:15 +0300 Message-ID: <20250724080313.605676-7-elena.reshetova@intel.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250724080313.605676-1-elena.reshetova@intel.com> References: <20250724080313.605676-1-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 Patch Contents =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. 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 Signed-off-by: Elena Reshetova --- arch/x86/kernel/cpu/sgx/main.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 206bf41d8325..90b7416969e4 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -921,6 +921,9 @@ EXPORT_SYMBOL_GPL(sgx_set_attribute); /* Counter to count the active SGX users */ static int __maybe_unused sgx_usage_count; =20 +/* Mutex to ensure no concurrent EPC accesses during EUPDATESVN */ +static DEFINE_MUTEX(sgx_svn_lock); + /** * sgx_update_svn() - Attempt to call ENCLS[EUPDATESVN]. * This instruction attempts to update CPUSVN to the @@ -937,7 +940,7 @@ static int __maybe_unused 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 @@ -983,12 +986,17 @@ static int __maybe_unused sgx_update_svn(void) =20 int sgx_inc_usage_count(void) { + guard(mutex)(&sgx_svn_lock); + + if (sgx_usage_count++ =3D=3D 0) + return sgx_update_svn(); + return 0; } =20 void sgx_dec_usage_count(void) { - return; + sgx_usage_count--; } =20 static int __init sgx_init(void) --=20 2.45.2