From 2a0f0dff043a4aa0f5c268bfb85244784d5e75cd Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Wed, 24 Sep 2025 09:57:11 -0700 Subject: [PATCH] PCI/sysfs: Ensure devices are powered for config reads commit 48991e4935078b05f80616c75d1ee2ea3ae18e58 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 d2bd39c0456b ("PCI: Store all PCIe Supported Link Speeds"). Fixes: 56c1af4606f0 ("PCI: Add sysfs max_link_speed/width, current_link_speed/width, etc") Signed-off-by: Brian Norris Signed-off-by: Brian Norris Signed-off-by: Bjorn Helgaas Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20250924095711.v2.1.Ibb5b6ca1e2c059e04ec53140cd98a44f2684c668@changeid Signed-off-by: Greg Kroah-Hartman --- drivers/pci/pci-sysfs.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index e1a980179dc14..3d1faaff50c94 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -196,8 +196,14 @@ static ssize_t max_link_width_show(struct device *dev, struct device_attribute *attr, char *buf) { 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); @@ -209,7 +215,10 @@ static ssize_t current_link_speed_show(struct device *dev, int err; enum pci_bus_speed speed; + pci_config_pm_runtime_get(pci_dev); err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat); + pci_config_pm_runtime_put(pci_dev); + if (err) return -EINVAL; @@ -226,7 +235,10 @@ static ssize_t current_link_width_show(struct device *dev, u16 linkstat; int err; + pci_config_pm_runtime_get(pci_dev); err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat); + pci_config_pm_runtime_put(pci_dev); + if (err) return -EINVAL; @@ -242,7 +254,10 @@ static ssize_t secondary_bus_number_show(struct device *dev, u8 sec_bus; int err; + pci_config_pm_runtime_get(pci_dev); err = pci_read_config_byte(pci_dev, PCI_SECONDARY_BUS, &sec_bus); + pci_config_pm_runtime_put(pci_dev); + if (err) return -EINVAL; @@ -258,7 +273,10 @@ static ssize_t subordinate_bus_number_show(struct device *dev, u8 sub_bus; int err; + pci_config_pm_runtime_get(pci_dev); err = pci_read_config_byte(pci_dev, PCI_SUBORDINATE_BUS, &sub_bus); + pci_config_pm_runtime_put(pci_dev); + if (err) return -EINVAL; -- 2.47.3