6.4-stable review patch. If anyone has any objections, please let me know.
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From: Feiyang Chen chenfeiyang@loongson.cn
commit 5694ba13b004eea683c6d4faeb6d6e7a9636bda0 upstream.
For a device with no Power Management Capability, pci_power_up() previously returned 0 (success) if the platform was able to put the device in D0, which led to pci_set_full_power_state() trying to read PCI_PM_CTRL, even though it doesn't exist.
Since dev->pm_cap == 0 in this case, pci_set_full_power_state() actually read the wrong register, interpreted it as PCI_PM_CTRL, and corrupted dev->current_state. This led to messages like this in some cases:
pci 0000:01:00.0: Refused to change power state from D3hot to D0
To prevent this, make pci_power_up() always return a negative failure code if the device lacks a Power Management Capability, even if non-PCI platform power management has been able to put the device in D0. The failure will prevent pci_set_full_power_state() from trying to access PCI_PM_CTRL.
Fixes: e200904b275c ("PCI/PM: Split pci_power_up()") Link: https://lore.kernel.org/r/20230824013738.1894965-1-chenfeiyang@loongson.cn Signed-off-by: Feiyang Chen chenfeiyang@loongson.cn Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: "Rafael J. Wysocki" rafael@kernel.org Cc: stable@vger.kernel.org # v5.19+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pci/pci.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
--- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1200,6 +1200,10 @@ static int pci_dev_wait(struct pci_dev * * * On success, return 0 or 1, depending on whether or not it is necessary to * restore the device's BARs subsequently (1 is returned in that case). + * + * On failure, return a negative error code. Always return failure if @dev + * lacks a Power Management Capability, even if the platform was able to + * put the device in D0 via non-PCI means. */ int pci_power_up(struct pci_dev *dev) { @@ -1216,9 +1220,6 @@ int pci_power_up(struct pci_dev *dev) else dev->current_state = state;
- if (state == PCI_D0) - return 0; - return -EIO; }
@@ -1276,8 +1277,12 @@ static int pci_set_full_power_state(stru int ret;
ret = pci_power_up(dev); - if (ret < 0) + if (ret < 0) { + if (dev->current_state == PCI_D0) + return 0; + return ret; + }
pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr); dev->current_state = pmcsr & PCI_PM_CTRL_STATE_MASK;