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Message-ID: <a8c83435-4c91-495c-950c-4d12b955c54c@kernel.org>
Date: Tue, 20 May 2025 10:23:57 -0500
From: Mario Limonciello <superm1@...nel.org>
To: Raag Jadav <raag.jadav@...el.com>, Denis Benato <benato.denis96@...il.com>
Cc: rafael@...nel.org, mahesh@...ux.ibm.com, oohall@...il.com,
bhelgaas@...gle.com, linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, ilpo.jarvinen@...ux.intel.com,
lukas@...ner.de, aravind.iddamsetty@...ux.intel.com
Subject: Re: [PATCH v4] PCI: Prevent power state transition of erroneous
device
On 5/20/2025 4:48 AM, Raag Jadav wrote:
> On Mon, May 19, 2025 at 11:42:31PM +0200, Denis Benato wrote:
>> On 5/19/25 12:41, Raag Jadav wrote:
>>> On Mon, May 19, 2025 at 03:58:08PM +0530, Raag Jadav wrote:
>>>> If error status is set on an AER capable device, most likely either the
>>>> device recovery is in progress or has already failed. Neither of the
>>>> cases are well suited for power state transition of the device, since
>>>> this can lead to unpredictable consequences like resume failure, or in
>>>> worst case the device is lost because of it. Leave the device in its
>>>> existing power state to avoid such issues.
>>>>
>>>> Signed-off-by: Raag Jadav <raag.jadav@...el.com>
>>>> ---
>>>>
>>>> v2: Synchronize AER handling with PCI PM (Rafael)
>>>> v3: Move pci_aer_in_progress() to pci_set_low_power_state() (Rafael)
>>>> Elaborate "why" (Bjorn)
>>>> v4: Rely on error status instead of device status
>>>> Condense comment (Lukas)
>>> Since pci_aer_in_progress() is changed I've not included Rafael's tag with
>>> my understanding of this needing a revisit. If this was a mistake, please
>>> let me know.
>>>
>>> Denis, Mario, does this fix your issue?
>>>
>> Hello,
>>
>> Unfortunately no, I have prepared a dmesg but had to remove the bootup process because it was too long of a few kb: https://pastebin.com/1uBEA1FL
>
> Thanks for the test. It seems there's no hotplug event this time around
> and endpoint device is still intact without any PCI related failure.
>
> Also,
>
> amdgpu 0000:09:00.0: PCI PM: Suspend power state: D3hot
>
> Which means whatever you're facing is either not related to this patch,
> or at best exposed some nasty side-effect that's not handled correctly
> by the driver.
>
> I'd say amdgpu folks would be of better help for your case.
>
> Raag
So according to the logs Denis shared with v4
(https://pastebin.com/1uBEA1FL) the GPU should have been going to BOCO.
This stands for "Bus off Chip Off"
amdgpu 0000:09:00.0: amdgpu: Using BOCO for runtime pm
If it's going to D3hot - that's not going to be BOCO, it should be going
to D3cold.
Denis, can you redo your logs with out Raag's patch patch and set
CONFIG_PCI_DEBUG to compare? The 6.14.6 log you shared already
(https://pastebin.com/kLZtibcD) also chooses BOCO but I'm suspecting
picks D3cold like it should.
>
>>>> More discussion on [1].
>>>> [1] https://lore.kernel.org/all/CAJZ5v0g-aJXfVH+Uc=9eRPuW08t-6PwzdyMXsC6FZRKYJtY03Q@mail.gmail.com/
>>>>
>>>> drivers/pci/pci.c | 9 +++++++++
>>>> drivers/pci/pcie/aer.c | 13 +++++++++++++
>>>> include/linux/aer.h | 2 ++
>>>> 3 files changed, 24 insertions(+)
>>>>
>>>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>>>> index 4d7c9f64ea24..a20018692933 100644
>>>> --- a/drivers/pci/pci.c
>>>> +++ b/drivers/pci/pci.c
>>>> @@ -9,6 +9,7 @@
>>>> */
>>>>
>>>> #include <linux/acpi.h>
>>>> +#include <linux/aer.h>
>>>> #include <linux/kernel.h>
>>>> #include <linux/delay.h>
>>>> #include <linux/dmi.h>
>>>> @@ -1539,6 +1540,14 @@ static int pci_set_low_power_state(struct pci_dev *dev, pci_power_t state, bool
>>>> || (state == PCI_D2 && !dev->d2_support))
>>>> return -EIO;
>>>>
>>>> + /*
>>>> + * If error status is set on an AER capable device, it is not well
>>>> + * suited for power state transition. Leave it in its existing power
>>>> + * state to avoid issues like unpredictable resume failure.
>>>> + */
>>>> + if (pci_aer_in_progress(dev))
>>>> + return -EIO;
>>>> +
>>>> pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
>>>> if (PCI_POSSIBLE_ERROR(pmcsr)) {
>>>> pci_err(dev, "Unable to change power state from %s to %s, device inaccessible\n",
>>>> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
>>>> index a1cf8c7ef628..617fbac0d38a 100644
>>>> --- a/drivers/pci/pcie/aer.c
>>>> +++ b/drivers/pci/pcie/aer.c
>>>> @@ -237,6 +237,19 @@ int pcie_aer_is_native(struct pci_dev *dev)
>>>> }
>>>> EXPORT_SYMBOL_NS_GPL(pcie_aer_is_native, "CXL");
>>>>
>>>> +bool pci_aer_in_progress(struct pci_dev *dev)
>>>> +{
>>>> + int aer = dev->aer_cap;
>>>> + u32 cor, uncor;
>>>> +
>>>> + if (!pcie_aer_is_native(dev))
>>>> + return false;
>>>> +
>>>> + pci_read_config_dword(dev, aer + PCI_ERR_COR_STATUS, &cor);
>>>> + pci_read_config_dword(dev, aer + PCI_ERR_UNCOR_STATUS, &uncor);
>>>> + return cor || uncor;
>>>> +}
>>>> +
>>>> static int pci_enable_pcie_error_reporting(struct pci_dev *dev)
>>>> {
>>>> int rc;
>>>> diff --git a/include/linux/aer.h b/include/linux/aer.h
>>>> index 02940be66324..e6a380bb2e68 100644
>>>> --- a/include/linux/aer.h
>>>> +++ b/include/linux/aer.h
>>>> @@ -56,12 +56,14 @@ struct aer_capability_regs {
>>>> #if defined(CONFIG_PCIEAER)
>>>> int pci_aer_clear_nonfatal_status(struct pci_dev *dev);
>>>> int pcie_aer_is_native(struct pci_dev *dev);
>>>> +bool pci_aer_in_progress(struct pci_dev *dev);
>>>> #else
>>>> static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
>>>> {
>>>> return -EINVAL;
>>>> }
>>>> static inline int pcie_aer_is_native(struct pci_dev *dev) { return 0; }
>>>> +static inline bool pci_aer_in_progress(struct pci_dev *dev) { return false; }
>>>> #endif
>>>>
>>>> void pci_print_aer(struct pci_dev *dev, int aer_severity,
>>>> --
>>>> 2.34.1
>>>>
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