On Wed, Oct 04, 2023 at 09:47:31AM -0500, Mario Limonciello wrote:
> Before d3cold was stable userspace was allowed to influence the kernel's
> decision of whether to enable d3cold for a device by a sysfs file
> `d3cold_allowed`. This potentially allows userspace to break the suspend
> for the system.
Is "Before d3cold was stable" referring to a "d3cold" read-only
variable, or to Linux functionality of using D3cold, or ...?
In what sense does the `d3cold_allowed` sysfs file break suspend?
> For debugging purposes `pci_port_pm=` can be used to control whether
> a PCI port will go into D3cold and runtime PM can be turned off by
> sysfs on PCI end points.
I guess this should be "pcie_port_pm=", which affects *all* PCIe
ports?
Which sysfs file turns off runtime PM for endpoints?
> Change the sysfs attribute to a noop that ignores the input when written
> and shows a warning. Simplify the internal kernel logic to drop
> `d3cold_allowed`.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
> v1->v2:
> * Leave R/W and show a warning instead
> * Mark deprecated in sysfs file
> ---
> Documentation/ABI/testing/sysfs-bus-pci | 4 ++--
> drivers/pci/pci-acpi.c | 2 +-
> drivers/pci/pci-sysfs.c | 14 ++------------
> drivers/pci/pci.c | 3 +--
> include/linux/pci.h | 1 -
> 5 files changed, 6 insertions(+), 18 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
> index ecf47559f495..b5db141dfee6 100644
> --- a/Documentation/ABI/testing/sysfs-bus-pci
> +++ b/Documentation/ABI/testing/sysfs-bus-pci
> @@ -283,8 +283,8 @@ Description:
> device will never be put into D3Cold state. If it is set, the
> device may be put into D3Cold state if other requirements are
> satisfied too. Reading this attribute will show the current
> - value of d3cold_allowed bit. Writing this attribute will set
> - the value of d3cold_allowed bit.
> + value of no_d3cold bit.
> + Writing to this attribute is deprecated and will do nothing.
>
> What: /sys/bus/pci/devices/.../sriov_totalvfs
> Date: November 2012
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index 05b7357bd258..a05350a4e49c 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -911,7 +911,7 @@ pci_power_t acpi_pci_choose_state(struct pci_dev *pdev)
> {
> int acpi_state, d_max;
>
> - if (pdev->no_d3cold || !pdev->d3cold_allowed)
> + if (pdev->no_d3cold)
> d_max = ACPI_STATE_D3_HOT;
> else
> d_max = ACPI_STATE_D3_COLD;
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index 5e741a05cf2c..52ed5a55a371 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -523,17 +523,7 @@ static ssize_t d3cold_allowed_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - struct pci_dev *pdev = to_pci_dev(dev);
> - unsigned long val;
> -
> - if (kstrtoul(buf, 0, &val) < 0)
> - return -EINVAL;
> -
> - pdev->d3cold_allowed = !!val;
> - pci_bridge_d3_update(pdev);
> -
> - pm_runtime_resume(dev);
> -
> + dev_warn_once(dev, "pci: writing to d3cold_allowed is deprecated\n");
> return count;
> }
>
> @@ -541,7 +531,7 @@ static ssize_t d3cold_allowed_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> struct pci_dev *pdev = to_pci_dev(dev);
> - return sysfs_emit(buf, "%u\n", pdev->d3cold_allowed);
> + return sysfs_emit(buf, "%u\n", !pdev->no_d3cold);
> }
> static DEVICE_ATTR_RW(d3cold_allowed);
> #endif
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 59c01d68c6d5..8c5a6f68f63d 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -3067,7 +3067,7 @@ static int pci_dev_check_d3cold(struct pci_dev *dev, void *data)
> bool *d3cold_ok = data;
>
> if (/* The device needs to be allowed to go D3cold ... */
> - dev->no_d3cold || !dev->d3cold_allowed ||
> + dev->no_d3cold ||
>
> /* ... and if it is wakeup capable to do so from D3cold. */
> (device_may_wakeup(&dev->dev) &&
> @@ -3204,7 +3204,6 @@ void pci_pm_init(struct pci_dev *dev)
> dev->d3hot_delay = PCI_PM_D3HOT_WAIT;
> dev->d3cold_delay = PCI_PM_D3COLD_WAIT;
> dev->bridge_d3 = pci_bridge_d3_possible(dev);
> - dev->d3cold_allowed = true;
>
> dev->d1_support = false;
> dev->d2_support = false;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 8c7c2c3c6c65..5f4ed71d31f5 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -376,7 +376,6 @@ struct pci_dev {
> unsigned int no_d1d2:1; /* D1 and D2 are forbidden */
> unsigned int no_d3cold:1; /* D3cold is forbidden */
> unsigned int bridge_d3:1; /* Allow D3 for bridge */
> - unsigned int d3cold_allowed:1; /* D3cold is allowed by user */
> unsigned int mmio_always_on:1; /* Disallow turning off io/mem
> decoding during BAR sizing */
> unsigned int wakeup_prepared:1;
> --
> 2.34.1
>
