This is a note to let you know that I've just added the patch titled
PCI/sysfs: Protect driver's D3cold preference from user space
to the 6.6-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-sysfs-protect-driver-s-d3cold-preference-from-user-space.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 70b70a4307cccebe91388337b1c85735ce4de6ff Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@xxxxxxxxx>
Date: Mon, 18 Sep 2023 14:48:01 +0200
Subject: PCI/sysfs: Protect driver's D3cold preference from user space
From: Lukas Wunner <lukas@xxxxxxxxx>
commit 70b70a4307cccebe91388337b1c85735ce4de6ff upstream.
struct pci_dev contains two flags which govern whether the device may
suspend to D3cold:
* no_d3cold provides an opt-out for drivers (e.g. if a device is known
to not wake from D3cold)
* d3cold_allowed provides an opt-out for user space (default is true,
user space may set to false)
Since commit 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend"),
the user space setting overwrites the driver setting. Essentially user
space is trusted to know better than the driver whether D3cold is
working.
That feels unsafe and wrong. Assume that the change was introduced
inadvertently and do not overwrite no_d3cold when d3cold_allowed is
modified. Instead, consider d3cold_allowed in addition to no_d3cold
when choosing a suspend state for the device.
That way, user space may opt out of D3cold if the driver hasn't, but it
may no longer force an opt in if the driver has opted out.
Fixes: 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend")
Link: https://lore.kernel.org/r/b8a7f4af2b73f6b506ad8ddee59d747cbf834606.1695025365.git.lukas@xxxxxxxxx
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Reviewed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.8+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pci/pci-acpi.c | 2 +-
drivers/pci/pci-sysfs.c | 5 +----
2 files changed, 2 insertions(+), 5 deletions(-)
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -911,7 +911,7 @@ pci_power_t acpi_pci_choose_state(struct
{
int acpi_state, d_max;
- if (pdev->no_d3cold)
+ if (pdev->no_d3cold || !pdev->d3cold_allowed)
d_max = ACPI_STATE_D3_HOT;
else
d_max = ACPI_STATE_D3_COLD;
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -529,10 +529,7 @@ static ssize_t d3cold_allowed_store(stru
return -EINVAL;
pdev->d3cold_allowed = !!val;
- if (pdev->d3cold_allowed)
- pci_d3cold_enable(pdev);
- else
- pci_d3cold_disable(pdev);
+ pci_bridge_d3_update(pdev);
pm_runtime_resume(dev);
Patches currently in stable-queue which might be from lukas@xxxxxxxxx are
queue-6.6/pci-sysfs-protect-driver-s-d3cold-preference-from-user-space.patch
