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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 51E3BC433E7 for ; Sat, 10 Oct 2020 03:13:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A0E622247 for ; Sat, 10 Oct 2020 03:13:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="edx7xet+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730618AbgJJDLr (ORCPT ); Fri, 9 Oct 2020 23:11:47 -0400 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:11466 "EHLO hqnvemgate24.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730256AbgJJCyU (ORCPT ); Fri, 9 Oct 2020 22:54:20 -0400 Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Fri, 09 Oct 2020 19:51:17 -0700 Received: from [10.2.51.144] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Sat, 10 Oct 2020 02:53:07 +0000 Subject: Re: [PATCH RFC PKS/PMEM 57/58] nvdimm/pmem: Stray access protection for pmem->virt_addr To: , Andrew Morton , "Thomas Gleixner" , Ingo Molnar , "Borislav Petkov" , Andy Lutomirski , Peter Zijlstra CC: , Dave Hansen , Dan Williams , Fenghua Yu , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <20201009195033.3208459-1-ira.weiny@intel.com> <20201009195033.3208459-58-ira.weiny@intel.com> From: John Hubbard Message-ID: Date: Fri, 9 Oct 2020 19:53:07 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201009195033.3208459-58-ira.weiny@intel.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1602298277; bh=hKwlK3WolBLUufkeWDHCi6j+X4NXa8gQFiKyGjbOY3s=; h=Subject:To:CC:References:From:Message-ID:Date:User-Agent: MIME-Version:In-Reply-To:Content-Type:Content-Language: Content-Transfer-Encoding:X-Originating-IP:X-ClientProxiedBy; b=edx7xet+HWktPTMH7LfazMaeZj84i5/Le7BE3m/9xNKYA9bmh246jZEvn48F/uMcW RRn8BggXdwK6EgYw84fvX6LW3WH/wQjijcVtcfekd8K6KkJdzgyiWWhhWRHsAgsUWu ErO3rgTi0L/NWozRhmjxim3aejVQ7k0j+Xmczu6ahvjgHQEdG1f6IxukspiHHh4eDZ vXW13vRjbU9kKvq3xSMRRweChxuwg1Gt9UWgcBiwICYzh7lbhEKe0zR7+e8y/8iSgu 9o2Hr0ioZGbS1OLU7+SDtKlkAPg/fZiUxFefl5DnOwU2H5+VRhK6GCiKvAXlVbpTMd H8SS1utYxNiTQ== Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 10/9/20 12:50 PM, ira.weiny@intel.com wrote: > From: Ira Weiny > > The pmem driver uses a cached virtual address to access its memory > directly. Because the nvdimm driver is well aware of the special > protections it has mapped memory with, we call dev_access_[en|dis]able() > around the direct pmem->virt_addr (pmem_addr) usage instead of the > unnecessary overhead of trying to get a page to kmap. > > Signed-off-by: Ira Weiny > --- > drivers/nvdimm/pmem.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c > index fab29b514372..e4dc1ae990fc 100644 > --- a/drivers/nvdimm/pmem.c > +++ b/drivers/nvdimm/pmem.c > @@ -148,7 +148,9 @@ static blk_status_t pmem_do_read(struct pmem_device *pmem, > if (unlikely(is_bad_pmem(&pmem->bb, sector, len))) > return BLK_STS_IOERR; > > + dev_access_enable(false); > rc = read_pmem(page, page_off, pmem_addr, len); > + dev_access_disable(false); Hi Ira! The APIs should be tweaked to use a symbol (GLOBAL, PER_THREAD), instead of true/false. Try reading the above and you'll see that it sounds like it's doing the opposite of what it is ("enable_this(false)" sounds like a clumsy API design to *disable*, right?). And there is no hint about the scope. And it *could* be so much more readable like this: dev_access_enable(DEV_ACCESS_THIS_THREAD); thanks, -- John Hubbard NVIDIA