From patchwork Wed Oct 16 18:37:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 11193917 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D288817E6 for ; Wed, 16 Oct 2019 18:37:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3AAA2067D for ; Wed, 16 Oct 2019 18:37:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726776AbfJPShu (ORCPT ); Wed, 16 Oct 2019 14:37:50 -0400 Received: from mga07.intel.com ([134.134.136.100]:22394 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2394289AbfJPSht (ORCPT ); Wed, 16 Oct 2019 14:37:49 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Oct 2019 11:37:48 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.67,304,1566889200"; d="scan'208";a="397258423" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.41]) by fmsmga006.fm.intel.com with ESMTP; 16 Oct 2019 11:37:47 -0700 From: Sean Christopherson To: Jarkko Sakkinen Cc: linux-sgx@vger.kernel.org Subject: [PATCH for_v23 v3 04/12] x86/sgx: Drop mmap_sem before EEXTENDing an enclave page Date: Wed, 16 Oct 2019 11:37:37 -0700 Message-Id: <20191016183745.8226-5-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20191016183745.8226-1-sean.j.christopherson@intel.com> References: <20191016183745.8226-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 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 4169ff3c81d8..7be3fdc846d7 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -409,11 +409,15 @@ 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; @@ -433,7 +437,6 @@ 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: @@ -443,7 +446,6 @@ 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);