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 6FD7442049; Wed, 16 Jul 2025 17:02:41 +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=1752685361; cv=none; b=pQVX3a1+LVvpl17R3J7kEaR9LSztXWaFWBGyOgWrIcrEL35PbiknZUDy1xEoABPyEJQPzSJbI6kOuFKCpRzxlNJmYuSjP4gWtaVrxS+qZvL+Y68EeCdF9yDUKi9dL7B2HDTqJHEro/rrHvO6xgxitsgSc62S/o2MMeij84npuGc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752685361; c=relaxed/simple; bh=Nk8r5lNpqHLsdZRzSm9gX+C1MJ9SZPhZTOf9SPBThE4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UUvnlUsfwuNW1+pN9BtQK8+nXCGIE/sK7yy+W2DNfH/sRfwSmY94UFuS1ZXyephPInQBPuAr8etxngXbF5o/OntJ3JCnLUpS7I0OWWaYXcYIRf2fAFQihVEghVh1RQE8SsNSsI57Xh48Tk9Vex61L470veMaGlu5oFuszkLAPIM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M0hz4ujV; 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="M0hz4ujV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A556C4CEF0; Wed, 16 Jul 2025 17:02:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752685361; bh=Nk8r5lNpqHLsdZRzSm9gX+C1MJ9SZPhZTOf9SPBThE4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=M0hz4ujVXE1KJoc71fTUWld9G+IpQLR6Um2ibxRYH181fHJtv3kl3CvVGDnxFjEU+ COQtMsW5XUGiBEpgtDGcH/KRbS3ta3foPVTJQmkCydCAjI0rWzL9QC+CPqjrquN5o+ cqmKO8A3SnLINk1fWj5O2/N6SVREhJSUB6W42pGm45hR8BK3r7IpQqzN+Pz7QWgHuo nZjGAwbdivlc0ezxyIrwAsKi0jcxnXD4Z+vz5aUxUf3mULtp13c7qOo2yg0DUFPOou okSvVfhHr/5Uka08xAvJe9nmx5pkw4DrgcrW7Aq71Py+Gh2ZFauHa3x78n4zWEc0Ud 2Xd952f1lQbMg== Message-ID: <7cae9919-4ccd-41ed-a899-0e97ee2c0250@kernel.org> Date: Wed, 16 Jul 2025 12:02:39 -0500 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] PCI/sysfs: Expose PCIe device serial number To: Matthew Wood , Bjorn Helgaas Cc: Jonathan Cameron , =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org References: <20250716163213.469226-1-thepacketgeek@gmail.com> <20250716163213.469226-2-thepacketgeek@gmail.com> Content-Language: en-US From: Mario Limonciello In-Reply-To: <20250716163213.469226-2-thepacketgeek@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/16/25 11:32 AM, Matthew Wood wrote: > Add a single sysfs read-only interface for reading PCIe device serial > numbers from userspace in a programmatic way. This device attribute > uses the same hexadecimal 1-byte dashed formatting as lspci serial number > capability output. If a device doesn't support the serial number > capability, the device_serial_number sysfs attribute will not be visible. > > Signed-off-by: Matthew Wood > --- > Documentation/ABI/testing/sysfs-bus-pci | 7 +++++++ > drivers/pci/pci-sysfs.c | 27 ++++++++++++++++++++++--- > 2 files changed, 31 insertions(+), 3 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci > index 69f952fffec7..f7e84b3a4204 100644 > --- a/Documentation/ABI/testing/sysfs-bus-pci > +++ b/Documentation/ABI/testing/sysfs-bus-pci > @@ -612,3 +612,10 @@ Description: > > # ls doe_features > 0001:01 0001:02 doe_discovery > + > +What: /sys/bus/pci/devices/.../device_serial_number > +Date: July 2025 > +Contact: Matthew Wood > +Description: > + This is visible only for PCIe devices that support the serial > + number extended capability. The file is read only. > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c > index 268c69daa4d5..b7b52dea6e31 100644 > --- a/drivers/pci/pci-sysfs.c > +++ b/drivers/pci/pci-sysfs.c > @@ -239,6 +239,22 @@ static ssize_t current_link_width_show(struct device *dev, > } > static DEVICE_ATTR_RO(current_link_width); > > +static ssize_t device_serial_number_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct pci_dev *pci_dev = to_pci_dev(dev); > + u64 dsn; > + > + dsn = pci_get_dsn(pci_dev); > + if (!dsn) > + return -EIO; > + > + return sysfs_emit(buf, "%02llx-%02llx-%02llx-%02llx-%02llx-%02llx-%02llx-%02llx\n", > + dsn >> 56, (dsn >> 48) & 0xff, (dsn >> 40) & 0xff, (dsn >> 32) & 0xff, > + (dsn >> 24) & 0xff, (dsn >> 16) & 0xff, (dsn >> 8) & 0xff, dsn & 0xff); > +} > +static DEVICE_ATTR_RO(device_serial_number); The serial number /could/ be considered sensitive information. I think it's better to use DEVICE_ATTR_ADMIN_RO. Also, as this is a "device" attribute is it really necessary to encode the extra word and "number"? > + > static ssize_t secondary_bus_number_show(struct device *dev, > struct device_attribute *attr, > char *buf) > @@ -660,6 +676,7 @@ static struct attribute *pcie_dev_attrs[] = { > &dev_attr_current_link_width.attr, > &dev_attr_max_link_width.attr, > &dev_attr_max_link_speed.attr, > + &dev_attr_device_serial_number.attr, > NULL, > }; > > @@ -1749,10 +1766,14 @@ static umode_t pcie_dev_attrs_are_visible(struct kobject *kobj, > struct device *dev = kobj_to_dev(kobj); > struct pci_dev *pdev = to_pci_dev(dev); > > - if (pci_is_pcie(pdev)) > - return a->mode; > + if (!pci_is_pcie(pdev)) > + return 0; > + > + if (a == &dev_attr_device_serial_number.attr && !pci_get_dsn(pdev)) > + return 0; > + > + return a->mode; > > - return 0; > } > > static const struct attribute_group pci_dev_group = {