Patch "PCI / PM: Force devices to D0 in pci_pm_thaw_noirq()" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    PCI / PM: Force devices to D0 in pci_pm_thaw_noirq()

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pci-pm-force-devices-to-d0-in-pci_pm_thaw_noirq.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 5839ee7389e893a31e4e3c9cf17b50d14103c902 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Fri, 15 Dec 2017 03:07:18 +0100
Subject: PCI / PM: Force devices to D0 in pci_pm_thaw_noirq()

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

commit 5839ee7389e893a31e4e3c9cf17b50d14103c902 upstream.

It is incorrect to call pci_restore_state() for devices in low-power
states (D1-D3), as that involves the restoration of MSI setup which
requires MMIO to be operational and that is only the case in D0.

However, pci_pm_thaw_noirq() may do that if the driver's "freeze"
callbacks put the device into a low-power state, so fix it by making
it force devices into D0 via pci_set_power_state() instead of trying
to "update" their power state which is pointless.

Fixes: e60514bd4485 (PCI/PM: Restore the status of PCI devices across hibernation)
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Maarten Lankhorst <dev@mblankhorst.nl>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Maarten Lankhorst <dev@mblankhorst.nl>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/pci/pci-driver.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -944,7 +944,12 @@ static int pci_pm_thaw_noirq(struct devi
 	if (pci_has_legacy_pm_support(pci_dev))
 		return pci_legacy_resume_early(dev);
 
-	pci_update_current_state(pci_dev, PCI_D0);
+	/*
+	 * pci_restore_state() requires the device to be in D0 (because of MSI
+	 * restoration among other things), so force it into D0 in case the
+	 * driver's "freeze" callbacks put it into a low-power state directly.
+	 */
+	pci_set_power_state(pci_dev, PCI_D0);
 	pci_restore_state(pci_dev);
 
 	if (drv && drv->pm && drv->pm->thaw_noirq)


Patches currently in stable-queue which might be from rafael.j.wysocki@intel.com are

queue-4.4/pci-pm-force-devices-to-d0-in-pci_pm_thaw_noirq.patch
queue-4.4/acpi-apei-erst-fix-missing-error-handling-in-erst_reader.patch