Re: [RFC PATCH 6/9] PCI: Add 'rcec' field to pci_dev for associated RCiEPs

Jonathan Cameron
2020-07-27T16:11:08Z

On Mon, 27 Jul 2020 12:23:58 +0100
Jonathan Cameron <Jonathan.Cameron@Huawei.com> wrote:

> On Fri, 24 Jul 2020 10:22:20 -0700
> Sean V Kelley <sean.v.kelley@intel.com> wrote:
>
> > From: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
> >
> > When attempting error recovery for an RCiEP associated with an RCEC device,
> > there needs to be a way to update the Root Error Status, the Uncorrectable
> > Error Status and the Uncorrectable Error Severity of the parent RCEC.
> > So add the 'rcec' field to the pci_dev structure and provide a hook for the
> > Root Port Driver to associate RCiEPs with their respective parent RCEC.
> >
> > Co-developed-by: Sean V Kelley <sean.v.kelley@intel.com>
> > Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
> > Signed-off-by: Sean V Kelley <sean.v.kelley@intel.com>
>
> I haven't tested yet, but I think there is one path in here that breaks
> my case (no OS visible rcec / all done in firmware GHESv2 / APEI)
>
> Jonathan
>
> > ---
> > drivers/pci/pcie/aer.c | 9 +++++----
> > drivers/pci/pcie/err.c | 9 +++++++++
> > drivers/pci/pcie/portdrv_pci.c | 15 +++++++++++++++
> > include/linux/pci.h | 3 +++
> > 4 files changed, 32 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> > index 3acf56683915..f1bf06be449e 100644
> > --- a/drivers/pci/pcie/aer.c
> > +++ b/drivers/pci/pcie/aer.c
> > @@ -1335,17 +1335,18 @@ static int aer_probe(struct pcie_device *dev)
> > static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
> > {
> > int aer = dev->aer_cap;
> > + int rc = 0;
> > u32 reg32;
> > - int rc;
> > -
> >
> > /* Disable Root's interrupt in response to error messages */
> > pci_read_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, &reg32);
> > reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK;
> > pci_write_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, reg32);
> >
> > - rc = pci_bus_error_reset(dev);
> > - pci_info(dev, "Root Port link has been reset\n");
> > + if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_EC) {
> > + rc = pci_bus_error_reset(dev);
> > + pci_info(dev, "Root Port link has been reset\n");
> > + }
> >
> > /* Clear Root Error Status */
> > pci_read_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, &reg32);
> > diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> > index 9b3ec94bdf1d..0aae7643132e 100644
> > --- a/drivers/pci/pcie/err.c
> > +++ b/drivers/pci/pcie/err.c
> > @@ -203,6 +203,11 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> > pci_walk_dev_affected(dev, report_frozen_detected, &status);
> > if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) {
> > status = flr_on_rciep(dev);
> > + /*
> > + * The callback only clears the Root Error Status
> > + * of the RCEC (see aer.c).
> > + */
> > + reset_link(dev->rcec);
>
> This looks dangerous for my case where APEI / GHESv2 is used. In that case
> we don't expose an RCEC at all. I don't think the reset_link callback
> is safe to a null pointer here. Fix may be as simple as
> if (dev->rcec)
> reset_link(dev->rcec);
>
>
> > if (status != PCI_ERS_RESULT_RECOVERED) {
> > pci_warn(dev, "function level reset failed\n");
> > goto failed;
> > @@ -246,7 +251,11 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> > pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC)) {
> > pci_aer_clear_device_status(dev);
> > pci_aer_clear_nonfatal_status(dev);
> > + } else if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) {
> > + pci_aer_clear_device_status(dev->rcec);
This needs updating as well to match current approach in Bjorn's tree

(reworked version of my fix for this in th !is_native case)

> > + pci_aer_clear_nonfatal_status(dev->rcec);
>
> These may be safe as in my both now have protections for !pcie_aer_is_native.
Except I'm wrong. That function performs a local check based
on the pci_dev passed in, so blows up anyway.

So this whole block needs an if(dev->rcec), or potentially protect it with
a call to pci_aer_is_native(dev) on the basis we shouldn't be able to get
here unless we are not doing native aer or we have an rcec.

Jonathan

>
> > }
> > +
> > pci_info(dev, "device recovery successful\n");
> > return status;
> >
> > diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
> > index d5b109499b10..f9409a0110c2 100644
> > --- a/drivers/pci/pcie/portdrv_pci.c
> > +++ b/drivers/pci/pcie/portdrv_pci.c
> > @@ -90,6 +90,18 @@ static const struct dev_pm_ops pcie_portdrv_pm_ops = {
> > #define PCIE_PORTDRV_PM_OPS NULL
> > #endif /* !PM */
> >
> > +static int pcie_hook_rcec(struct pci_dev *pdev, void *data)
> > +{
> > + struct pci_dev *rcec = (struct pci_dev *)data;
> > +
> > + pdev->rcec = rcec;
> > + pci_info(rcec, "RCiEP(under an RCEC) %04x:%02x:%02x.%d\n",
> > + pci_domain_nr(pdev->bus), pdev->bus->number,
> > + PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
>
> We may want to make this debug info at somepoint if we have a way
> of discovering it from userspace. The PCI boot up is extremely
> verbose already!
>
> > +
> > + return 0;
> > +}
> > +
> > /*
> > * pcie_portdrv_probe - Probe PCI-Express port devices
> > * @dev: PCI-Express port device being probed
> > @@ -110,6 +122,9 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
> > (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_EC)))
> > return -ENODEV;
> >
> > + if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC)
> > + pcie_walk_rcec(dev, pcie_hook_rcec, dev);
> > +
> > status = pcie_port_device_register(dev);
> > if (status)
> > return status;
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index 34c1c4f45288..e920f29df40b 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -326,6 +326,9 @@ struct pci_dev {
> > #ifdef CONFIG_PCIEAER
> > u16 aer_cap; /* AER capability offset */
> > struct aer_stats *aer_stats; /* AER stats for this device */
> > +#endif
> > +#ifdef CONFIG_PCIEPORTBUS
> > + struct pci_dev *rcec; /* Associated RCEC device */
> > #endif
> > u8 pcie_cap; /* PCIe capability offset */
> > u8 msi_cap; /* MSI capability offset */
>