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PCI/sysfs: Ensure devices are powered for config reads

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commit 48991e4935 upstream.

The "max_link_width", "current_link_speed", "current_link_width",
"secondary_bus_number", and "subordinate_bus_number" sysfs files all access
config registers, but they don't check the runtime PM state. If the device
is in D3cold or a parent bridge is suspended, we may see -EINVAL, bogus
values, or worse, depending on implementation details.

Wrap these access in pci_config_pm_runtime_{get,put}() like most of the
rest of the similar sysfs attributes.

Notably, "max_link_speed" does not access config registers; it returns a
cached value since d2bd39c045 ("PCI: Store all PCIe Supported Link
Speeds").

Fixes: 56c1af4606 ("PCI: Add sysfs max_link_speed/width, current_link_speed/width, etc")
Signed-off-by: Brian Norris <briannorris@google.com>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250924095711.v2.1.Ibb5b6ca1e2c059e04ec53140cd98a44f2684c668@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Brian Norris
2025-09-24 09:57:11 -07:00
committed by Greg Kroah-Hartman
parent d4f9b44e81
commit 3ea9bd4285
1 changed files with 19 additions and 1 deletions
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20
drivers/pci/pci-sysfs.c
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@@ -200,8 +200,14 @@ static ssize_t max_link_width_show(struct device *dev,
struct device_attribute *attr, char *buf) struct device_attribute *attr, char *buf)
{ {
struct pci_dev *pdev = to_pci_dev(dev); struct pci_dev *pdev = to_pci_dev(dev);
ssize_t ret;
return sysfs_emit(buf, "%u\n", pcie_get_width_cap(pdev)); /* We read PCI_EXP_LNKCAP, so we need the device to be accessible. */
pci_config_pm_runtime_get(pdev);
ret = sysfs_emit(buf, "%u\n", pcie_get_width_cap(pdev));
pci_config_pm_runtime_put(pdev);
return ret;
} }
static DEVICE_ATTR_RO(max_link_width); static DEVICE_ATTR_RO(max_link_width);
@@ -213,7 +219,10 @@ static ssize_t current_link_speed_show(struct device *dev,
int err; int err;
enum pci_bus_speed speed; enum pci_bus_speed speed;
pci_config_pm_runtime_get(pci_dev);
err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat); err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);
pci_config_pm_runtime_put(pci_dev);
if (err) if (err)
return -EINVAL; return -EINVAL;
@@ -230,7 +239,10 @@ static ssize_t current_link_width_show(struct device *dev,
u16 linkstat; u16 linkstat;
int err; int err;
pci_config_pm_runtime_get(pci_dev);
err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat); err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);
pci_config_pm_runtime_put(pci_dev);
if (err) if (err)
return -EINVAL; return -EINVAL;
@@ -246,7 +258,10 @@ static ssize_t secondary_bus_number_show(struct device *dev,
u8 sec_bus; u8 sec_bus;
int err; int err;
pci_config_pm_runtime_get(pci_dev);
err = pci_read_config_byte(pci_dev, PCI_SECONDARY_BUS, &sec_bus); err = pci_read_config_byte(pci_dev, PCI_SECONDARY_BUS, &sec_bus);
pci_config_pm_runtime_put(pci_dev);
if (err) if (err)
return -EINVAL; return -EINVAL;
@@ -262,7 +277,10 @@ static ssize_t subordinate_bus_number_show(struct device *dev,
u8 sub_bus; u8 sub_bus;
int err; int err;
pci_config_pm_runtime_get(pci_dev);
err = pci_read_config_byte(pci_dev, PCI_SUBORDINATE_BUS, &sub_bus); err = pci_read_config_byte(pci_dev, PCI_SUBORDINATE_BUS, &sub_bus);
pci_config_pm_runtime_put(pci_dev);
if (err) if (err)
return -EINVAL; return -EINVAL;