From patchwork Wed Apr 13 21:10:14 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Reinette Chatre X-Patchwork-Id: 12812671 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 1A832C433FE for ; Wed, 13 Apr 2022 21:10:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237785AbiDMVNS (ORCPT ); Wed, 13 Apr 2022 17:13:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239023AbiDMVNJ (ORCPT ); Wed, 13 Apr 2022 17:13:09 -0400 Received: from mga06.intel.com (mga06b.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DEE643BBD4; Wed, 13 Apr 2022 14:10:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1649884246; x=1681420246; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=qEYjDGikjF83YtBCeEvG4VbjIvJKkDSSfyUUy694La4=; b=FxmrLb1dHp+j3Oipaem4bKFLO5yqmENpyHSo8zherP3NABuopqd4S216 MocUezzFD09z8z57ZOJptqtt6xa5hupsAxFi2bWdu7IeqUT2B9A8E2ShI +v/Mh4wh4SdQTCZUkzEmjMROxntMgF+Gtnz2kWbbetutEdvC/msHpSfFv oJvJ97fcziFuGdTzNk9fqD1GKnQKlum3PEQBkq0hSO5frfa2vWKRJTGTs j9gUs5ieCpVQvMoQ+kN27Mnhx1gO4DD3r5yC0vSZQqYCGF5RcVTOp6hh+ H5Pbr/c9Rf4RA0dR4v0YrLepz+CHv1tX4M1DtE9IhAvNIii1BejMaXlDE A==; X-IronPort-AV: E=McAfee;i="6400,9594,10316"; a="323219031" X-IronPort-AV: E=Sophos;i="5.90,257,1643702400"; d="scan'208";a="323219031" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Apr 2022 14:10:44 -0700 X-IronPort-AV: E=Sophos;i="5.90,257,1643702400"; d="scan'208";a="725054280" Received: from rchatre-ws.ostc.intel.com ([10.54.69.144]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Apr 2022 14:10:43 -0700 From: Reinette Chatre To: dave.hansen@linux.intel.com, jarkko@kernel.org, tglx@linutronix.de, bp@alien8.de, luto@kernel.org, mingo@redhat.com, linux-sgx@vger.kernel.org, x86@kernel.org, shuah@kernel.org, linux-kselftest@vger.kernel.org Cc: seanjc@google.com, kai.huang@intel.com, cathy.zhang@intel.com, cedric.xing@intel.com, haitao.huang@intel.com, mark.shanahan@intel.com, vijay.dhanraj@intel.com, hpa@zytor.com, linux-kernel@vger.kernel.org Subject: [PATCH V4 14/31] x86/sgx: Support VA page allocation without reclaiming Date: Wed, 13 Apr 2022 14:10:14 -0700 Message-Id: <0ab32196f5056b25c34fb89fcc4dc28a5d875d2e.1649878359.git.reinette.chatre@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org struct sgx_encl should be protected with the mutex sgx_encl->lock. One exception is sgx_encl->page_cnt that is incremented (in sgx_encl_grow()) when an enclave page is added to the enclave. The reason the mutex is not held is to allow the reclaimer to be called directly if there are no EPC pages (in support of a new VA page) available at the time. Incrementing sgx_encl->page_cnt without sgc_encl->lock held is currently (before SGX2) safe from concurrent updates because all paths in which sgx_encl_grow() is called occur before enclave initialization and are protected with an atomic operation on SGX_ENCL_IOCTL. SGX2 includes support for dynamically adding pages after enclave initialization where the protection of SGX_ENCL_IOCTL is not available. Make direct reclaim of EPC pages optional when new VA pages are added to the enclave. Essentially the existing "reclaim" flag used when regular EPC pages are added to an enclave becomes available to the caller when used to allocate VA pages instead of always being "true". When adding pages without invoking the reclaimer it is possible to do so with sgx_encl->lock held, gaining its protection against concurrent updates to sgx_encl->page_cnt after enclave initialization. No functional change. Reported-by: Haitao Huang Tested-by: Haitao Huang Signed-off-by: Reinette Chatre Reviewed-by: Jarkko Sakkinen --- Changes since V3: - New patch prompted by Haitao encountering the WARN_ON_ONCE(encl->page_cnt % SGX_VA_SLOT_COUNT) within sgx_encl_grow() during his SGX2 multi-threaded unit tests. arch/x86/kernel/cpu/sgx/encl.c | 6 ++++-- arch/x86/kernel/cpu/sgx/encl.h | 4 ++-- arch/x86/kernel/cpu/sgx/ioctl.c | 8 ++++---- 3 files changed, 10 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index 546423753e4c..92516aeca405 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -869,6 +869,8 @@ void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr) /** * sgx_alloc_va_page() - Allocate a Version Array (VA) page + * @reclaim: Reclaim EPC pages directly if none available. Enclave + * mutex should not be held if this is set. * * Allocate a free EPC page and convert it to a Version Array (VA) page. * @@ -876,12 +878,12 @@ void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr) * a VA page, * -errno otherwise */ -struct sgx_epc_page *sgx_alloc_va_page(void) +struct sgx_epc_page *sgx_alloc_va_page(bool reclaim) { struct sgx_epc_page *epc_page; int ret; - epc_page = sgx_alloc_epc_page(NULL, true); + epc_page = sgx_alloc_epc_page(NULL, reclaim); if (IS_ERR(epc_page)) return ERR_CAST(epc_page); diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h index 253ebdd1c5be..66adb8faec45 100644 --- a/arch/x86/kernel/cpu/sgx/encl.h +++ b/arch/x86/kernel/cpu/sgx/encl.h @@ -116,14 +116,14 @@ struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl, unsigned long offset, u64 secinfo_flags); void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr); -struct sgx_epc_page *sgx_alloc_va_page(void); +struct sgx_epc_page *sgx_alloc_va_page(bool reclaim); unsigned int sgx_alloc_va_slot(struct sgx_va_page *va_page); void sgx_free_va_slot(struct sgx_va_page *va_page, unsigned int offset); bool sgx_va_page_full(struct sgx_va_page *va_page); void sgx_encl_free_epc_page(struct sgx_epc_page *page); struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl, unsigned long addr); -struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl); +struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl, bool reclaim); void sgx_encl_shrink(struct sgx_encl *encl, struct sgx_va_page *va_page); #endif /* _X86_ENCL_H */ diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index bb8cdb2ad0d1..5d41aa204761 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -17,7 +17,7 @@ #include "encl.h" #include "encls.h" -struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl) +struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl, bool reclaim) { struct sgx_va_page *va_page = NULL; void *err; @@ -30,7 +30,7 @@ struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl) if (!va_page) return ERR_PTR(-ENOMEM); - va_page->epc_page = sgx_alloc_va_page(); + va_page->epc_page = sgx_alloc_va_page(reclaim); if (IS_ERR(va_page->epc_page)) { err = ERR_CAST(va_page->epc_page); kfree(va_page); @@ -64,7 +64,7 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs) struct file *backing; long ret; - va_page = sgx_encl_grow(encl); + va_page = sgx_encl_grow(encl, true); if (IS_ERR(va_page)) return PTR_ERR(va_page); else if (va_page) @@ -275,7 +275,7 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src, return PTR_ERR(epc_page); } - va_page = sgx_encl_grow(encl); + va_page = sgx_encl_grow(encl, true); if (IS_ERR(va_page)) { ret = PTR_ERR(va_page); goto err_out_free;