Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752370AbdGDUIv (ORCPT ); Tue, 4 Jul 2017 16:08:51 -0400 Received: from g2t2353.austin.hpe.com ([15.233.44.26]:43826 "EHLO g2t2353.austin.hpe.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752215AbdGDUIu (ORCPT ); Tue, 4 Jul 2017 16:08:50 -0400 Date: Tue, 4 Jul 2017 14:08:49 -0600 From: Jerry Hoemann To: Dan Williams Cc: "linux-nvdimm@lists.01.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v4 3/6] libnvdimm, acpi, nfit: Add bus level dsm mask for pass thru. Message-ID: <20170704200849.GA15713@anatevka.americas.hpqcorp.net> Reply-To: Jerry.Hoemann@hpe.com References: <293ee143dcabb386ca06b384a384171c256a2ecc.1498810220.git.jerry.hoemann@hpe.com> <20170701195805.GA13259@anatevka.americas.hpqcorp.net> <20170701203813.GA13574@anatevka.americas.hpqcorp.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4146 Lines: 89 On Sat, Jul 01, 2017 at 01:46:03PM -0700, Dan Williams wrote: > On Sat, Jul 1, 2017 at 1:38 PM, Jerry Hoemann wrote: > > On Sat, Jul 01, 2017 at 01:10:31PM -0700, Dan Williams wrote: > >> On Sat, Jul 1, 2017 at 1:08 PM, Dan Williams wrote: > >> > On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann wrote: > >> >> On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: > >> >> > >> >> ... > >> >> > >> >>> On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann wrote: > >> >>> > + if (cmd == ND_CMD_CALL) > >> >>> > + dsm_mask = nd_desc->bus_dsm_mask; > >> >>> > desc = nd_cmd_bus_desc(cmd); > >> >>> > uuid = to_nfit_uuid(NFIT_DEV_BUS); > >> >>> > handle = adev->handle; > >> >>> > @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) > >> >>> > struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; > >> >>> > const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); > >> >>> > struct acpi_device *adev; > >> >>> > + unsigned long dsm_mask; > >> >>> > int i; > >> >>> > > >> >>> > nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; > >> >>> > @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) > >> >>> > if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) > >> >>> > set_bit(i, &nd_desc->cmd_mask); > >> >>> > set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); > >> >>> > + > >> >>> > + dsm_mask = 0x3bf; > >> >>> > >> >>> I went ahead and fixed this up to use dsm_mask defined like this: > >> >>> > >> >>> + dsm_mask = > >> >>> + (1 << ND_CMD_ARS_CAP) | > >> >>> + (1 << ND_CMD_ARS_START) | > >> >>> + (1 << ND_CMD_ARS_STATUS) | > >> >>> + (1 << ND_CMD_CLEAR_ERROR) | > >> >>> + (1 << NFIT_CMD_TRANSLATE_SPA) | > >> >>> + (1 << NFIT_CMD_ARS_INJECT_SET) | > >> >>> + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | > >> >>> + (1 << NFIT_CMD_ARS_INJECT_GET); > >> >>> > >> >>> This drops function number 0 which userspace has no need to call. > >> >> > >> >> Actually I like to call function 0. Its an excellent test when > >> >> modifying the code path as its a no side effects function whose output > >> >> is known in advance and instantly recognizable. I also use it when > >> >> testing new firmware. > >> >> > >> >> What is the downside to allowing it? What bad things happen? > >> > > >> > It allows implementations to bypass the standardization process and > >> > ship new root DSMs. It's always possible to patch the kernel locally > >> > for development, so I see no reason to ship this capability globally. > > > > I don't understand this comment, but I think your next comment > > essentially says to disregard this comment? > > Yes, sorry. > > >> Actually, just the discovery portion does not lead to this leak, but > >> it's redundant when we have the 'dsm_mask' sysfs attribute. > > > > No. The generation of the mask in sysfs is not done by > > executing the code in acpi_nfit_ctl. One of the reasons I call > > function 0 to test changes I am making to the ioctl path itself. > > The sysfs has nothing to do with that path and cannot be used > > to serve this purpose. > > > > And since the content of sysfs has been edited it also can not be > > used as a basic test of firmware. > > > > What is the downside to allowing the calling of function 0? > > It needlessly expands the kernel ABI. I would suggest, if you want to No. It is not needless. It is not an ABI extension. Same goes for the override feature. I hope that ACPI doesn't extend the specification in the future because we'll just have to redo these patches yet again. -- ----------------------------------------------------------------------------- Jerry Hoemann Software Engineer Hewlett Packard Enterprise -----------------------------------------------------------------------------