Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752135AbdGAUqG (ORCPT ); Sat, 1 Jul 2017 16:46:06 -0400 Received: from mail-yw0-f176.google.com ([209.85.161.176]:35735 "EHLO mail-yw0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751978AbdGAUqE (ORCPT ); Sat, 1 Jul 2017 16:46:04 -0400 MIME-Version: 1.0 In-Reply-To: <20170701203813.GA13574@anatevka.americas.hpqcorp.net> References: <293ee143dcabb386ca06b384a384171c256a2ecc.1498810220.git.jerry.hoemann@hpe.com> <20170701195805.GA13259@anatevka.americas.hpqcorp.net> <20170701203813.GA13574@anatevka.americas.hpqcorp.net> From: Dan Williams Date: Sat, 1 Jul 2017 13:46:03 -0700 Message-ID: Subject: Re: [PATCH v4 3/6] libnvdimm, acpi, nfit: Add bus level dsm mask for pass thru. To: Jerry Hoemann Cc: "linux-nvdimm@lists.01.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3793 Lines: 79 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 test acpi_nfit_ctl() path changes, expand the existing test infrastructure we have in nfit_ctl_test(). If you want to test firmware you don't need the upstream kernel to carry firmware debug enabling in the production path, but I would support expanding tools/testing/nvdimm/ to make it easier to test firmware.