Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752119AbdGAUiQ (ORCPT ); Sat, 1 Jul 2017 16:38:16 -0400 Received: from g2t2354.austin.hpe.com ([15.233.44.27]:33563 "EHLO g2t2354.austin.hpe.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751968AbdGAUiP (ORCPT ); Sat, 1 Jul 2017 16:38:15 -0400 Date: Sat, 1 Jul 2017 14:38:13 -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: <20170701203813.GA13574@anatevka.americas.hpqcorp.net> Reply-To: Jerry.Hoemann@hpe.com References: <293ee143dcabb386ca06b384a384171c256a2ecc.1498810220.git.jerry.hoemann@hpe.com> <20170701195805.GA13259@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: 3487 Lines: 78 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? > > 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? -- ----------------------------------------------------------------------------- Jerry Hoemann Software Engineer Hewlett Packard Enterprise -----------------------------------------------------------------------------