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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7248E92729 for ; Thu, 5 Oct 2023 18:53:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230466AbjJESxZ (ORCPT ); Thu, 5 Oct 2023 14:53:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230183AbjJESxY (ORCPT ); Thu, 5 Oct 2023 14:53:24 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9AA7D98; Thu, 5 Oct 2023 11:53:17 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0D027C433C7; Thu, 5 Oct 2023 18:53:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696531997; bh=chYFievT/u2R2Xpv24rtGTlpheFGgMYWE/+zxnqxkdY=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=RrzGi5/URDgDNTXjNM5T2qbqstYXXCkWKLk/hQALtR15Na0VYXcuRRnBSrL4bgKR0 tgXsaksM2u/HeVdwbBR+p6xdFxOkIGpFMSnqRez4j31QSA7CJD+1OOZejWJeVjpsNZ w7K9D2Nd/3ZnOinKGaunyb2FFSu8Mq8mWmeWZuMGaFubwvhW1Zz5uUBxvEk6B9TtqJ zq5qo7/lSKtLXIGUtY5vUhihWKRFFnhXH7XshwH4X7tYYwXGAoxQ6OW1e/6BwEFdzJ mGCquss2yWEWZPeq5wfR+N8Rnh4hALOKnfXtTsaSGmufhHMyDjVNoQAF9YTXhk61Os shl7rhcepBH3w== Date: Thu, 5 Oct 2023 13:53:15 -0500 From: Bjorn Helgaas To: Mario Limonciello Cc: bhelgaas@google.com, lukas@wunner.de, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, mika.westerberg@linux.intel.com Subject: Re: [PATCH v2] PCI: Make d3cold_allowed sysfs attribute read only Message-ID: <20231005185315.GA785324@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231004144731.158342-1-mario.limonciello@amd.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Wed, Oct 04, 2023 at 09:47:31AM -0500, Mario Limonciello wrote: > Before d3cold was stable userspace was allowed to influence the kernel's > decision of whether to enable d3cold for a device by a sysfs file > `d3cold_allowed`. This potentially allows userspace to break the suspend > for the system. Is "Before d3cold was stable" referring to a "d3cold" read-only variable, or to Linux functionality of using D3cold, or ...? In what sense does the `d3cold_allowed` sysfs file break suspend? > For debugging purposes `pci_port_pm=` can be used to control whether > a PCI port will go into D3cold and runtime PM can be turned off by > sysfs on PCI end points. I guess this should be "pcie_port_pm=", which affects *all* PCIe ports? Which sysfs file turns off runtime PM for endpoints? > Change the sysfs attribute to a noop that ignores the input when written > and shows a warning. Simplify the internal kernel logic to drop > `d3cold_allowed`. > > Signed-off-by: Mario Limonciello > --- > v1->v2: > * Leave R/W and show a warning instead > * Mark deprecated in sysfs file > --- > Documentation/ABI/testing/sysfs-bus-pci | 4 ++-- > drivers/pci/pci-acpi.c | 2 +- > drivers/pci/pci-sysfs.c | 14 ++------------ > drivers/pci/pci.c | 3 +-- > include/linux/pci.h | 1 - > 5 files changed, 6 insertions(+), 18 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci > index ecf47559f495..b5db141dfee6 100644 > --- a/Documentation/ABI/testing/sysfs-bus-pci > +++ b/Documentation/ABI/testing/sysfs-bus-pci > @@ -283,8 +283,8 @@ Description: > device will never be put into D3Cold state. If it is set, the > device may be put into D3Cold state if other requirements are > satisfied too. Reading this attribute will show the current > - value of d3cold_allowed bit. Writing this attribute will set > - the value of d3cold_allowed bit. > + value of no_d3cold bit. > + Writing to this attribute is deprecated and will do nothing. > > What: /sys/bus/pci/devices/.../sriov_totalvfs > Date: November 2012 > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c > index 05b7357bd258..a05350a4e49c 100644 > --- a/drivers/pci/pci-acpi.c > +++ b/drivers/pci/pci-acpi.c > @@ -911,7 +911,7 @@ pci_power_t acpi_pci_choose_state(struct pci_dev *pdev) > { > int acpi_state, d_max; > > - if (pdev->no_d3cold || !pdev->d3cold_allowed) > + if (pdev->no_d3cold) > d_max = ACPI_STATE_D3_HOT; > else > d_max = ACPI_STATE_D3_COLD; > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c > index 5e741a05cf2c..52ed5a55a371 100644 > --- a/drivers/pci/pci-sysfs.c > +++ b/drivers/pci/pci-sysfs.c > @@ -523,17 +523,7 @@ static ssize_t d3cold_allowed_store(struct device *dev, > struct device_attribute *attr, > const char *buf, size_t count) > { > - struct pci_dev *pdev = to_pci_dev(dev); > - unsigned long val; > - > - if (kstrtoul(buf, 0, &val) < 0) > - return -EINVAL; > - > - pdev->d3cold_allowed = !!val; > - pci_bridge_d3_update(pdev); > - > - pm_runtime_resume(dev); > - > + dev_warn_once(dev, "pci: writing to d3cold_allowed is deprecated\n"); > return count; > } > > @@ -541,7 +531,7 @@ static ssize_t d3cold_allowed_show(struct device *dev, > struct device_attribute *attr, char *buf) > { > struct pci_dev *pdev = to_pci_dev(dev); > - return sysfs_emit(buf, "%u\n", pdev->d3cold_allowed); > + return sysfs_emit(buf, "%u\n", !pdev->no_d3cold); > } > static DEVICE_ATTR_RW(d3cold_allowed); > #endif > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 59c01d68c6d5..8c5a6f68f63d 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -3067,7 +3067,7 @@ static int pci_dev_check_d3cold(struct pci_dev *dev, void *data) > bool *d3cold_ok = data; > > if (/* The device needs to be allowed to go D3cold ... */ > - dev->no_d3cold || !dev->d3cold_allowed || > + dev->no_d3cold || > > /* ... and if it is wakeup capable to do so from D3cold. */ > (device_may_wakeup(&dev->dev) && > @@ -3204,7 +3204,6 @@ void pci_pm_init(struct pci_dev *dev) > dev->d3hot_delay = PCI_PM_D3HOT_WAIT; > dev->d3cold_delay = PCI_PM_D3COLD_WAIT; > dev->bridge_d3 = pci_bridge_d3_possible(dev); > - dev->d3cold_allowed = true; > > dev->d1_support = false; > dev->d2_support = false; > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 8c7c2c3c6c65..5f4ed71d31f5 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -376,7 +376,6 @@ struct pci_dev { > unsigned int no_d1d2:1; /* D1 and D2 are forbidden */ > unsigned int no_d3cold:1; /* D3cold is forbidden */ > unsigned int bridge_d3:1; /* Allow D3 for bridge */ > - unsigned int d3cold_allowed:1; /* D3cold is allowed by user */ > unsigned int mmio_always_on:1; /* Disallow turning off io/mem > decoding during BAR sizing */ > unsigned int wakeup_prepared:1; > -- > 2.34.1 >