From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41438ECE597 for ; Thu, 10 Oct 2019 22:55:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1B34D218AC for ; Thu, 10 Oct 2019 22:55:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726705AbfJJWzk (ORCPT ); Thu, 10 Oct 2019 18:55:40 -0400 Received: from mga06.intel.com ([134.134.136.31]:20137 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726616AbfJJWzj (ORCPT ); Thu, 10 Oct 2019 18:55:39 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Oct 2019 15:55:38 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.67,281,1566889200"; d="scan'208";a="197400458" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.41]) by orsmga003.jf.intel.com with ESMTP; 10 Oct 2019 15:55:38 -0700 From: Sean Christopherson To: Jarkko Sakkinen Cc: linux-sgx@vger.kernel.org Subject: [PATCH for_v23 4/4] x86/sgx: Drop mmap_sem before EEXTENDing an enclave page Date: Thu, 10 Oct 2019 15:55:30 -0700 Message-Id: <20191010225530.26400-5-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20191010225530.26400-1-sean.j.christopherson@intel.com> References: <20191010225530.26400-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-sgx-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org Drop mmap_sem, which needs to be held for read across EADD, prior to doing EEXTEND on the newly added page to avoid holding mmap_sem for an extended duration. EEXTEND doesn't access user pages and holding encl->lock without mmap_sem is perfectly ok, while EEXTEND is a _slow_ operation, to the point where it operates on 256-byte chunks instead of 4k pages to maintain a reasonable latency for a single instruction. Signed-off-by: Sean Christopherson --- arch/x86/kernel/cpu/sgx/ioctl.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index fd4117f18564..46f2769d16fe 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -403,11 +403,15 @@ static int sgx_encl_add_page(struct sgx_encl *encl, */ ret = radix_tree_insert(&encl->page_tree, PFN_DOWN(encl_page->desc), encl_page); - if (ret) + if (ret) { + up_read(¤t->mm->mmap_sem); goto err_out_unlock; + } ret = __sgx_encl_add_page(encl, encl_page, epc_page, secinfo, addp->src); + up_read(¤t->mm->mmap_sem); + if (ret) goto err_out; @@ -427,7 +431,6 @@ static int sgx_encl_add_page(struct sgx_encl *encl, sgx_mark_page_reclaimable(encl_page->epc_page); mutex_unlock(&encl->lock); - up_read(¤t->mm->mmap_sem); return ret; err_out: @@ -437,7 +440,6 @@ static int sgx_encl_add_page(struct sgx_encl *encl, err_out_unlock: sgx_encl_shrink(encl, va_page); mutex_unlock(&encl->lock); - up_read(¤t->mm->mmap_sem); err_out_free: sgx_free_page(epc_page); -- 2.22.0