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Date: Tue, 21 Jul 2015 13:09:19 -0500
From: Bjorn Helgaas <bhelgaas@...gle.com>
To: Jordan Hargrave <jharg93@...il.com>
Cc: jdelvare@...e.de, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, Jordan_Hargrave@...l.com
Subject: Re: [PATCH] Add support for reading SMBIOS Slot number for PCI
devices
On Fri, Jul 10, 2015 at 05:02:46PM -0500, Jordan Hargrave wrote:
> From: Jordan Hargrave <Jordan_Hargrave@...l.com>
>
> There currently isn't an easy way to determine which PCI devices belong to
> system slots. This patch adds support to read SMBIOS Type 9 (System Slots).
>
> Signed-off-by: Jordan Hargrave <Jordan_Hargrave@...l.com>
> ---
> drivers/firmware/dmi_scan.c | 39 ++++++++++++++++++++
> drivers/pci/pci-label.c | 89 +++++++++++++++++++++++++++++++++++++++++++++
> include/linux/dmi.h | 1 +
> 3 files changed, 129 insertions(+)
>
> diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
> index ac1ce4a..8f95897 100644
> --- a/drivers/firmware/dmi_scan.c
> +++ b/drivers/firmware/dmi_scan.c
> @@ -356,6 +356,41 @@ static void __init dmi_save_extended_devices(const struct dmi_header *dm)
> dmi_save_one_device(*d & 0x7f, dmi_string_nosave(dm, *(d - 1)));
> }
>
> +static void __init dmi_save_dev_slot(int instance, int segment, int bus, int devfn, const char *name)
> +{
> + struct dmi_dev_onboard *slot;
> +
> + slot = dmi_alloc(sizeof(*slot) + strlen(name) + 1);
> + if (!slot) {
> + printk(KERN_ERR "dmi_save_system_slot: out of memory.\n");
You've got lots of data that might be useful in the printk: segment, bus,
devfn, name.
> + return;
> + }
> + slot->instance = instance;
> + slot->segment = segment;
> + slot->bus = bus;
> + slot->devfn = devfn;
> +
> + strcpy((char *)&slot[1], name);
> + slot->dev.type = DMI_DEV_TYPE_SYSTEM_SLOT;
> + slot->dev.name = (char *)&slot[1];
> + slot->dev.device_data = slot;
> +
> + list_add(&slot->dev.list, &dmi_devices);
> +}
> +
> +
> +static void __init dmi_save_system_slot(const struct dmi_header *dm)
> +{
> + const char *name;
> + const u8 *d = (u8*)dm;
> +
> + if (dm->type == DMI_ENTRY_SYSTEM_SLOT && dm->length >= 0x11) {
> + name = dmi_string_nosave(dm, *(d + 0x04));
> + dmi_save_dev_slot(*(u16 *)(d + 0x09), *(u16 *)(d + 0xD),
> + *(d + 0xF), *(d + 0x10), name);
> + }
> +}
> +
> static void __init count_mem_devices(const struct dmi_header *dm, void *v)
> {
> if (dm->type != DMI_ENTRY_MEM_DEVICE)
> @@ -437,6 +472,10 @@ static void __init dmi_decode(const struct dmi_header *dm, void *dummy)
> break;
> case 41: /* Onboard Devices Extended Information */
> dmi_save_extended_devices(dm);
> + break;
> + case 9: /* System Slots */
> + dmi_save_system_slot(dm);
> + break;
> }
> }
>
> diff --git a/drivers/pci/pci-label.c b/drivers/pci/pci-label.c
> index 024b5c1..38dfb45 100644
> --- a/drivers/pci/pci-label.c
> +++ b/drivers/pci/pci-label.c
> @@ -125,14 +125,103 @@ static struct attribute_group smbios_attr_group = {
> .is_visible = smbios_instance_string_exist,
> };
>
> +static int smbios_getslot(struct pci_dev *pdev)
> +{
> + struct pci_dev *sdev;
> + struct dmi_dev_onboard *dslot;
> + const struct dmi_device *dmi;
> + u8 sub, sec, bus;
> +
> + dmi = NULL;
> + if (pdev->is_virtfn) {
> + /* Get Physical device for SR-IOV */
> + pdev = pdev->physfn;
> + }
Use pci_physfn().
> + bus = pdev->bus->number;
> + while ((dmi = dmi_find_device(DMI_DEV_TYPE_SYSTEM_SLOT, NULL, dmi)) != NULL) {
This loop doesn't match my naive expectation of how we should find a slot.
I expected something like:
- Look for DMI info that's an exact match for my D:B:D.F
- Walk bridges upstream towards the root, looking for a subtree that
includes pdev
> + sec = sub = -1;
> +
> + dslot = dmi->device_data;
> + sdev = pci_get_domain_bus_and_slot(dslot->segment, dslot->bus, dslot->devfn);
This acquires a reference on the dev returned, so you need to dispose of
that somewhere.
> + if (sdev == NULL)
> + continue;
> +
> + if (sdev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> + pci_read_config_byte(sdev, PCI_SECONDARY_BUS, &sec);
> + pci_read_config_byte(sdev, PCI_SUBORDINATE_BUS, &sub);
We should not have to read this out of config space; busn_res in struct
pci_bus has this information already.
> + if (bus >= sec && bus <= sub) {
> + /* device is child of bridge */
> + return dslot->instance;
If you have a slot name for 0000:00:00.0 and a device at 0001:00:00.0, this
will erroneously associate the domain 0 name with the domain 1 device.
> + }
> + }
> + if (pci_domain_nr(sdev->bus) == pci_domain_nr(pdev->bus) &&
> + sdev->bus->number == pdev->bus->number &&
> + PCI_SLOT(sdev->devfn) == PCI_SLOT(pdev->devfn)) {
> + /* Match domain:bus:dev. If PCIE root, only match function */
The PCIe part of this comment doesn't seem to match the code.
> + if (PCI_FUNC(sdev->devfn) == PCI_FUNC(pdev->devfn) ||
> + pci_pcie_type(sdev) != PCI_EXP_TYPE_ROOT_PORT) {
> + return dslot->instance;
> + }
> + }
> + }
> + return -ENODEV;
> +}
> +
> +static ssize_t smbiosslot_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct pci_dev *pdev;
> + int slot;
> +
> + pdev = to_pci_dev(dev);
> + slot = smbios_getslot(pdev);
> + if (slot > 0) {
> + return scnprintf(buf, PAGE_SIZE, "%d\n", slot);
> + }
> + return 0;
> +}
> +
> +static umode_t smbios_slot_exist(struct kobject *kobj, struct attribute *attr,
> + int n)
> +{
> + struct device *dev;
> + struct pci_dev *pdev;
> +
> + dev = container_of(kobj, struct device, kobj);
> + pdev = to_pci_dev(dev);
> +
> + return (smbios_getslot(pdev) > 0) ? S_IRUGO : 0;
> +}
> +
> +static struct device_attribute smbios_attr_slot = {
> + .attr = {.name = "slot", .mode = 0444},
> + .show = smbiosslot_show,
> +};
> +
> +static struct attribute *smbios_slot_attributes[] = {
> + &smbios_attr_slot.attr,
> + NULL,
> +};
> +
> +static struct attribute_group smbios_slot_attr_group = {
> + .attrs = smbios_slot_attributes,
> + .is_visible = smbios_slot_exist,
> +};
> +
> static int pci_create_smbiosname_file(struct pci_dev *pdev)
> {
> + int rc;
> +
> + rc = sysfs_create_group(&pdev->dev.kobj, &smbios_slot_attr_group);
> + if (rc != 0)
> + return rc;
> return sysfs_create_group(&pdev->dev.kobj, &smbios_attr_group);
> }
>
> static void pci_remove_smbiosname_file(struct pci_dev *pdev)
> {
> sysfs_remove_group(&pdev->dev.kobj, &smbios_attr_group);
> + sysfs_remove_group(&pdev->dev.kobj, &smbios_slot_attr_group);
> }
> #else
> static inline int pci_create_smbiosname_file(struct pci_dev *pdev)
> diff --git a/include/linux/dmi.h b/include/linux/dmi.h
> index 5055ac3..09f42e7 100644
> --- a/include/linux/dmi.h
> +++ b/include/linux/dmi.h
> @@ -22,6 +22,7 @@ enum dmi_device_type {
> DMI_DEV_TYPE_IPMI = -1,
> DMI_DEV_TYPE_OEM_STRING = -2,
> DMI_DEV_TYPE_DEV_ONBOARD = -3,
> + DMI_DEV_TYPE_SYSTEM_SLOT = -4,
> };
>
> enum dmi_entry_type {
> --
> 1.8.3.1
>
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