From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1916923498F; Wed, 4 Dec 2024 17:13:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733332391; cv=none; b=LLa8kme9votPsn2jq+DHjROlO+SsClDjK45mQ5SuRqDhRZ3osPKiElng3ww7FxsyXnaXVxs+YWYwtc6EHwa5KCh5Cim7PwVbpjHog0we1cbMCb6NWxcnP9ncdfquX6vGs0jWzo4wsQEcRFt6v1oU5rc6bxwnDVzRnXBlroJ4K0g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733332391; c=relaxed/simple; bh=3WNLnOxjJBL3DWclwkV+TqDYZigHtqH0wReUhpxHHEQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=m6YC1oI2H2lGWBNzd54j+o4RQpyd7kGLN+KSY7CAUnApbE2KOwYi0LKWI+RDUBYDZfNnQYFl+Uti19tBQjmw6AtX+5B8xvlJYkFxa97geYJR30FwWP/Ljf11Og5BMLGx3bH10besoEXKJ8yc15IM0Fc4U1RrcJ2CaNEUAcg1ZO4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UtPxAq69; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UtPxAq69" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61748C4CECD; Wed, 4 Dec 2024 17:13:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733332390; bh=3WNLnOxjJBL3DWclwkV+TqDYZigHtqH0wReUhpxHHEQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UtPxAq69v6g0zBM4eQRbHb2WluOaPxnJQUn4Q6p/tDwaj0JQSN5z/O1R3s3/6iF9z 1k2yLTNi61kTcuE739YgxypTqTt0cBuN9U0YdtBilZyIOmMMAITl7BbveCJBw8VFnk Nb92BCQvV08SvREsnGr/Mc3zEkE85H5+ucB0aB34uBZJbi4Zz2aqguLK0wvCtsU6zm L+tN3LASa0YVdKeH4xKgd87lYNAdmA4BfFUOSxQxLpucFjv+vI0dbcnlELmLCkPDd4 Jge64E7xSgaXrWeXtxS9OEN4IQCFJKFG1VLqhQYFpyQte1cy5hBuBcGR3mYKCgNSQx f9PUaT7op/chQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Keith Busch , Bjorn Helgaas , Alex Williamson , Amey Narkhede , Sasha Levin , mariusz.tkaczyk@linux.intel.com, ilpo.jarvinen@linux.intel.com, stuart.w.hayes@gmail.com, linux-pci@vger.kernel.org Subject: [PATCH AUTOSEL 6.1 4/6] PCI: Add 'reset_subordinate' to reset hierarchy below bridge Date: Wed, 4 Dec 2024 11:01:36 -0500 Message-ID: <20241204160142.2217017-4-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241204160142.2217017-1-sashal@kernel.org> References: <20241204160142.2217017-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.1.119 Content-Transfer-Encoding: 8bit From: Keith Busch [ Upstream commit 2fa046449a82a7d0f6d9721dd83e348816038444 ] The "bus" and "cxl_bus" reset methods reset a device by asserting Secondary Bus Reset on the bridge leading to the device. These only work if the device is the only device below the bridge. Add a sysfs 'reset_subordinate' attribute on bridges that can assert Secondary Bus Reset regardless of how many devices are below the bridge. This resets all the devices below a bridge in a single command, including the locking and config space save/restore that reset methods normally do. This may be the only way to reset devices that don't support other reset methods (ACPI, FLR, PM reset, etc). Link: https://lore.kernel.org/r/20241025222755.3756162-1-kbusch@meta.com Signed-off-by: Keith Busch [bhelgaas: commit log, add capable(CAP_SYS_ADMIN) check] Signed-off-by: Bjorn Helgaas Reviewed-by: Alex Williamson Reviewed-by: Amey Narkhede Signed-off-by: Sasha Levin --- Documentation/ABI/testing/sysfs-bus-pci | 11 +++++++++++ drivers/pci/pci-sysfs.c | 26 +++++++++++++++++++++++++ drivers/pci/pci.c | 2 +- drivers/pci/pci.h | 1 + 4 files changed, 39 insertions(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index 840727fc75dcf..6c5ca95a94105 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -163,6 +163,17 @@ Description: will be present in sysfs. Writing 1 to this file will perform reset. +What: /sys/bus/pci/devices/.../reset_subordinate +Date: October 2024 +Contact: linux-pci@vger.kernel.org +Description: + This is visible only for bridge devices. If you want to reset + all devices attached through the subordinate bus of a specific + bridge device, writing 1 to this will try to do it. This will + affect all devices attached to the system through this bridge + similiar to writing 1 to their individual "reset" file, so use + with caution. + What: /sys/bus/pci/devices/.../vpd Date: February 2008 Contact: Ben Hutchings diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index df1c44a5c886c..e1a980179dc14 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -517,6 +517,31 @@ static ssize_t bus_rescan_store(struct device *dev, static struct device_attribute dev_attr_bus_rescan = __ATTR(rescan, 0200, NULL, bus_rescan_store); +static ssize_t reset_subordinate_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct pci_dev *pdev = to_pci_dev(dev); + struct pci_bus *bus = pdev->subordinate; + unsigned long val; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (kstrtoul(buf, 0, &val) < 0) + return -EINVAL; + + if (val) { + int ret = __pci_reset_bus(bus); + + if (ret) + return ret; + } + + return count; +} +static DEVICE_ATTR_WO(reset_subordinate); + #if defined(CONFIG_PM) && defined(CONFIG_ACPI) static ssize_t d3cold_allowed_store(struct device *dev, struct device_attribute *attr, @@ -621,6 +646,7 @@ static struct attribute *pci_dev_attrs[] = { static struct attribute *pci_bridge_attrs[] = { &dev_attr_subordinate_bus_number.attr, &dev_attr_secondary_bus_number.attr, + &dev_attr_reset_subordinate.attr, NULL, }; diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 0baf5c03ef4cb..24c4096f55c0c 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5932,7 +5932,7 @@ EXPORT_SYMBOL_GPL(pci_probe_reset_bus); * * Same as above except return -EAGAIN if the bus cannot be locked */ -static int __pci_reset_bus(struct pci_bus *bus) +int __pci_reset_bus(struct pci_bus *bus) { int rc; diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 5d5813aa5b458..38ad75ce52c32 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -37,6 +37,7 @@ bool pci_reset_supported(struct pci_dev *dev); void pci_init_reset_methods(struct pci_dev *dev); int pci_bridge_secondary_bus_reset(struct pci_dev *dev); int pci_bus_error_reset(struct pci_dev *dev); +int __pci_reset_bus(struct pci_bus *bus); struct pci_cap_saved_data { u16 cap_nr; -- 2.43.0