From nobody Sun Dec 14 19:32:30 2025 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) (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 D8959335BC8; Thu, 16 Oct 2025 13:14:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.15 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760620450; cv=none; b=GQUs6+5bJtWARW3AFiz77hXcnKBTtyKzQXfTWIm87hgjBVpVXlI+hYx4xoeC8KlQNtwXbZduWYjloUKMObJY30uuEho6Flb/r8DSyjHuy41MaqfLC6/sWhvD3FEnrFaw1g99CGdXRt+NdN6lKOT9KmpZ238FhBb2zWihjiFTtaI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760620450; c=relaxed/simple; bh=XEWcIXPhVodD+hPjudKanXF8EQDvHpVubtWozV1Qmsg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VCvV3T9VIDHmqgR+FYACQWvaRuMcaIjP/ydzoFmhwuJ+vndAsfUN8vbnqbNrvtSOH6bxnaXSUGYvDtWuFCvdmHQrNXmQzI+KTgNwXJCH6WRmckR6ydbSx4bFh1EmlHRfousk4JEGbgKJOi4l9pzUXAHb0lkSMjaq4urlWzi3qYA= 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=HQ20DW7c; arc=none smtp.client-ip=192.198.163.15 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="HQ20DW7c" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1760620448; x=1792156448; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=XEWcIXPhVodD+hPjudKanXF8EQDvHpVubtWozV1Qmsg=; b=HQ20DW7cp+2I1GB/ylFHRnqs1AQJ8l77GH9v6xoTwoVDWRLEK+QkR7yr +TH12WLxG1/G6HSpHoW3XBJ0eAgiCtDBYiNORzmPA2l89j58XoKvr7L1V pN3433RfxDm9tnzJ/sdIZRBjE7aIB+DiJAecCizFMV5zshl6CUg4tXMZc JJFRjzZSqBUWzudg/F6SRoo3tesvdnKnmAfx0cBZoGKBecrKsyx7zeI24 oKsejhKo6nBCWPHIXfz8HXypAPZ+tilvGC1JlRgMNZNRUn+TM2f8G7etS c4mS5PVCT6XFAS9V9I3aBoFno+5JK0ztzLBHrw1Zizwd5LVFK8nOtME+Q g==; X-CSE-ConnectionGUID: xryI1h4cTTmw80ow+imDqA== X-CSE-MsgGUID: FZ4yMasiToqgGVesUIGIiA== X-IronPort-AV: E=McAfee;i="6800,10657,11584"; a="62904741" X-IronPort-AV: E=Sophos;i="6.19,234,1754982000"; d="scan'208";a="62904741" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Oct 2025 06:14:08 -0700 X-CSE-ConnectionGUID: Sf9Jlh63SPu6FiN6Ldu8zg== X-CSE-MsgGUID: 5rBIqRqKRfSHmmhTYhErBQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,234,1754982000"; d="scan'208";a="182016017" Received: from klitkey1-mobl1.ger.corp.intel.com (HELO eresheto-mobl3.ger.corp.intel.com) ([10.245.244.10]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Oct 2025 06:14:04 -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 v17 4/5] x86/sgx: Implement ENCLS[EUPDATESVN] Date: Thu, 16 Oct 2025 16:11:07 +0300 Message-ID: <20251016131314.17153-5-elena.reshetova@intel.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20251016131314.17153-1-elena.reshetova@intel.com> References: <20251016131314.17153-1-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-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" All running enclaves and cryptographic assets (such as internal SGX encryption keys) are assumed to be compromised whenever an SGX-related microcode update occurs. To mitigate this assumed compromise the new supervisor SGX instruction ENCLS[EUPDATESVN] can generate fresh cryptographic assets. Before executing EUPDATESVN, all SGX memory must be marked as unused. This requirement ensures that no potentially compromised enclave survives the update and allows the system to safely regenerate cryptographic assets. Add the method to perform ENCLS[EUPDATESVN]. However, until the follow up patch that wires calling sgx_update_svn() from sgx_inc_usage_count(), this code is not reachable. Reviewed-by: Kai Huang Reviewed-by: Jarkko Sakkinen Signed-off-by: Elena Reshetova Tested-by: Nataliia Bondarevska --- arch/x86/include/asm/sgx.h | 31 +++++++------- arch/x86/kernel/cpu/sgx/encls.h | 5 +++ arch/x86/kernel/cpu/sgx/main.c | 75 +++++++++++++++++++++++++++++++++ 3 files changed, 96 insertions(+), 15 deletions(-) diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h index 73348cf4fd78..c2c4c0d22ca4 100644 --- a/arch/x86/include/asm/sgx.h +++ b/arch/x86/include/asm/sgx.h @@ -28,21 +28,22 @@ #define SGX_CPUID_EPC_MASK GENMASK(3, 0) =20 enum sgx_encls_function { - ECREATE =3D 0x00, - EADD =3D 0x01, - EINIT =3D 0x02, - EREMOVE =3D 0x03, - EDGBRD =3D 0x04, - EDGBWR =3D 0x05, - EEXTEND =3D 0x06, - ELDU =3D 0x08, - EBLOCK =3D 0x09, - EPA =3D 0x0A, - EWB =3D 0x0B, - ETRACK =3D 0x0C, - EAUG =3D 0x0D, - EMODPR =3D 0x0E, - EMODT =3D 0x0F, + ECREATE =3D 0x00, + EADD =3D 0x01, + EINIT =3D 0x02, + EREMOVE =3D 0x03, + EDGBRD =3D 0x04, + EDGBWR =3D 0x05, + EEXTEND =3D 0x06, + ELDU =3D 0x08, + EBLOCK =3D 0x09, + EPA =3D 0x0A, + EWB =3D 0x0B, + ETRACK =3D 0x0C, + EAUG =3D 0x0D, + EMODPR =3D 0x0E, + EMODT =3D 0x0F, + EUPDATESVN =3D 0x18, }; =20 /** diff --git a/arch/x86/kernel/cpu/sgx/encls.h b/arch/x86/kernel/cpu/sgx/encl= s.h index 42a088a337c5..74be751199a4 100644 --- a/arch/x86/kernel/cpu/sgx/encls.h +++ b/arch/x86/kernel/cpu/sgx/encls.h @@ -233,4 +233,9 @@ static inline int __eaug(struct sgx_pageinfo *pginfo, v= oid *addr) return __encls_2(EAUG, pginfo, addr); } =20 +/* Attempt to update CPUSVN at runtime. */ +static inline int __eupdatesvn(void) +{ + return __encls_ret_1(EUPDATESVN, ""); +} #endif /* _X86_ENCLS_H */ diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 3a5cbd1c170e..ffc7b9496218 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -16,6 +16,7 @@ #include #include #include +#include #include "driver.h" #include "encl.h" #include "encls.h" @@ -917,6 +918,80 @@ int sgx_set_attribute(unsigned long *allowed_attribute= s, } EXPORT_SYMBOL_GPL(sgx_set_attribute); =20 +/* Counter to count the active SGX users */ +static int sgx_usage_count; + +/** + * sgx_update_svn() - Attempt to call ENCLS[EUPDATESVN]. + * + * This instruction attempts to update CPUSVN to the + * currently loaded microcode update SVN and generate new + * cryptographic assets. + * + * Return: + * * %0: - Success or not supported + * * %-EAGAIN: - Can be safely retried, failure is due to lack of + * * entropy in RNG + * * %-EIO: - Unexpected error, retries are not advisable + */ +static int __maybe_unused sgx_update_svn(void) +{ + int ret; + + /* + * If EUPDATESVN is not available, it is ok to + * silently skip it to comply with legacy behavior. + */ + if (!cpu_feature_enabled(X86_FEATURE_SGX_EUPDATESVN)) + return 0; + + /* + * EPC is guaranteed to be empty when there are no users. + * Ensure we are on our first user before proceeding further. + */ + WARN(sgx_usage_count, "Elevated usage count when calling EUPDATESVN\n"); + + for (int i =3D 0; i < RDRAND_RETRY_LOOPS; i++) { + ret =3D __eupdatesvn(); + + /* Stop on success or unexpected errors: */ + if (ret !=3D SGX_INSUFFICIENT_ENTROPY) + break; + } + + switch (ret) { + case 0: + /* + * SVN successfully updated. + * Let users know when the update was successful. + */ + pr_info("SVN updated successfully\n"); + return 0; + case SGX_NO_UPDATE: + /* + * SVN update failed since the current SVN is + * not newer than CPUSVN. This is the most + * common case and indicates no harm. + */ + return 0; + case SGX_INSUFFICIENT_ENTROPY: + /* + * SVN update failed due to lack of entropy in DRNG. + * Indicate to userspace that it should retry. + */ + return -EAGAIN; + default: + break; + } + + /* + * EUPDATESVN was called when EPC is empty, all other error + * codes are unexpected. + */ + ENCLS_WARN(ret, "EUPDATESVN"); + return -EIO; +} + int sgx_inc_usage_count(void) { return 0; --=20 2.45.2