Re: [PATCH v2 1/2] PCI/AER: Disable AER service when link is in L2/L3 ready, L2 and L3 state

[Kai-Heng Feng <kai.heng.feng@canonical.com>]

On Sun, Mar 20, 2022 at 4:38 AM Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@linux.intel.com> wrote:
>
>
>
> On 1/26/22 6:54 PM, Kai-Heng Feng wrote:
> > Commit 50310600ebda ("iommu/vt-d: Enable PCI ACS for platform opt in
> > hint") enables ACS, and some platforms lose its NVMe after resume from
>
> Why enabling ACS makes platform lose NVMe? Can you add more details
> about the problem?

I don't have a hardware analyzer, so the only detail I can provide is
the symptom.
I believe the affected system was sent Intel, and there wasn't any
feedback since then.

>
> > S3:
> > [   50.947816] pcieport 0000:00:1b.0: DPC: containment event, status:0x1f01 source:0x0000
> > [   50.947817] pcieport 0000:00:1b.0: DPC: unmasked uncorrectable error detected
> > [   50.947829] pcieport 0000:00:1b.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Receiver ID)
> > [   50.947830] pcieport 0000:00:1b.0:   device [8086:06ac] error status/mask=00200000/00010000
> > [   50.947831] pcieport 0000:00:1b.0:    [21] ACSViol                (First)
> > [   50.947841] pcieport 0000:00:1b.0: AER: broadcast error_detected message
> > [   50.947843] nvme nvme0: frozen state error detected, reset controller
> >
> > It happens right after ACS gets enabled during resume.
> >
> > There's another case, when Thunderbolt reaches D3cold:
> > [   30.100211] pcieport 0000:00:1d.0: AER: Uncorrected (Non-Fatal) error received: 0000:00:1d.0
> > [   30.100251] pcieport 0000:00:1d.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Requester ID)
> > [   30.100256] pcieport 0000:00:1d.0:   device [8086:7ab0] error status/mask=00100000/00004000
> > [   30.100262] pcieport 0000:00:1d.0:    [20] UnsupReq               (First)
> > [   30.100267] pcieport 0000:00:1d.0: AER:   TLP Header: 34000000 08000052 00000000 00000000
> > [   30.100372] thunderbolt 0000:0a:00.0: AER: can't recover (no error_detected callback)
>
> no callback message means one or more devices in the given port does not
> support error handler. How is this related to ACS?

This case is about D3cold, not related to ACS.
And no error_detected is just part of the message. The whole AER
message is more important.

Kai-Heng

>
> > [   30.100401] xhci_hcd 0000:3e:00.0: AER: can't recover (no error_detected callback)
> > [   30.100427] pcieport 0000:00:1d.0: AER: device recovery failed
> >
> > So disable AER service to avoid the noises from turning power rails
> > on/off when the device is in low power states (D3hot and D3cold), as
> > PCIe spec "5.2 Link State Power Management" states that TLP and DLLP
> > transmission is disabled for a Link in L2/L3 Ready (D3hot), L2 (D3cold
> > with aux power) and L3 (D3cold).
> >
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=209149
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215453
> > Fixes: 50310600ebda ("iommu/vt-d: Enable PCI ACS for platform opt in hint")
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> > ---
> > v2:
> >   - Wording change.
> >
> >   drivers/pci/pcie/aer.c | 31 +++++++++++++++++++++++++------
> >   1 file changed, 25 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> > index 9fa1f97e5b270..e4e9d4a3098d7 100644
> > --- a/drivers/pci/pcie/aer.c
> > +++ b/drivers/pci/pcie/aer.c
> > @@ -1367,6 +1367,22 @@ static int aer_probe(struct pcie_device *dev)
> >       return 0;
> >   }
> >
> > +static int aer_suspend(struct pcie_device *dev)
> > +{
> > +     struct aer_rpc *rpc = get_service_data(dev);
> > +
> > +     aer_disable_rootport(rpc);
> > +     return 0;
> > +}
> > +
> > +static int aer_resume(struct pcie_device *dev)
> > +{
> > +     struct aer_rpc *rpc = get_service_data(dev);
> > +
> > +     aer_enable_rootport(rpc);
> > +     return 0;
> > +}
> > +
> >   /**
> >    * aer_root_reset - reset Root Port hierarchy, RCEC, or RCiEP
> >    * @dev: pointer to Root Port, RCEC, or RCiEP
> > @@ -1433,12 +1449,15 @@ static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
> >   }
> >
> >   static struct pcie_port_service_driver aerdriver = {
> > -     .name           = "aer",
> > -     .port_type      = PCIE_ANY_PORT,
> > -     .service        = PCIE_PORT_SERVICE_AER,
> > -
> > -     .probe          = aer_probe,
> > -     .remove         = aer_remove,
> > +     .name                   = "aer",
> > +     .port_type              = PCIE_ANY_PORT,
> > +     .service                = PCIE_PORT_SERVICE_AER,
> > +     .probe                  = aer_probe,
> > +     .suspend                = aer_suspend,
> > +     .resume                 = aer_resume,
> > +     .runtime_suspend        = aer_suspend,
> > +     .runtime_resume         = aer_resume,
> > +     .remove                 = aer_remove,
> >   };
> >
> >   /**
>
> --
> Sathyanarayanan Kuppuswamy
> Linux Kernel Developer