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    SubjectRe: [RFC PATCH 6/9] PCI: Add 'rcec' field to pci_dev for associated RCiEPs
    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);
    > + pci_aer_clear_nonfatal_status(dev->rcec);

    These may be safe as in my both now have protections for !pcie_aer_is_native.

    > }
    > +
    > 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 */


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