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=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 077E3C433DF for ; Mon, 12 Oct 2020 05:52:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B4151207BB for ; Mon, 12 Oct 2020 05:52:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726969AbgJLFwV (ORCPT ); Mon, 12 Oct 2020 01:52:21 -0400 Received: from mga12.intel.com ([192.55.52.136]:18020 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726072AbgJLFwU (ORCPT ); Mon, 12 Oct 2020 01:52:20 -0400 IronPort-SDR: CLPkUE8ZXL9RG0hlY2fQGhUxycBLQsChKLafCW6TnTmty/B4AJSVoYo8VkwfX4+LMLJe/TrE5a 9755N6FOm/YQ== X-IronPort-AV: E=McAfee;i="6000,8403,9771"; a="145014271" X-IronPort-AV: E=Sophos;i="5.77,365,1596524400"; d="scan'208";a="145014271" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Oct 2020 22:52:20 -0700 IronPort-SDR: Ya9EDAn3SOMd08SCKVKBtueoni+yyq9EF8H8N9tr+YE/IrdFHweYy6SREcwPgxnde0DbbLRvxa rOKYCbITG9ew== X-IronPort-AV: E=Sophos;i="5.77,365,1596524400"; d="scan'208";a="520573207" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Oct 2020 22:52:19 -0700 Date: Sun, 11 Oct 2020 22:52:19 -0700 From: Ira Weiny To: John Hubbard Cc: Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , Peter Zijlstra , x86@kernel.org, Dave Hansen , Dan Williams , Fenghua Yu , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, kexec@lists.infradead.org, linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org, devel@driverdev.osuosl.org, linux-efi@vger.kernel.org, linux-mmc@vger.kernel.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-um@lists.infradead.org, linux-ntfs-dev@lists.sourceforge.net, reiserfs-devel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, cluster-devel@redhat.com, ecryptfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-afs@lists.infradead.org, linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, drbd-dev@lists.linbit.com, linux-block@vger.kernel.org, xen-devel@lists.xenproject.org, linux-cachefs@redhat.com, samba-technical@lists.samba.org, intel-wired-lan@lists.osuosl.org Subject: Re: [PATCH RFC PKS/PMEM 57/58] nvdimm/pmem: Stray access protection for pmem->virt_addr Message-ID: <20201012055218.GA2046448@iweiny-DESK2.sc.intel.com> References: <20201009195033.3208459-1-ira.weiny@intel.com> <20201009195033.3208459-58-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.1 (2018-12-01) Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Fri, Oct 09, 2020 at 07:53:07PM -0700, John Hubbard wrote: > 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. Sounds reasonable. > > And it *could* be so much more readable like this: > > dev_access_enable(DEV_ACCESS_THIS_THREAD); I'll think about the flag name. I'm not liking 'this thread'. Maybe DEV_ACCESS_[GLOBAL|THREAD] Ira