Re: [RFC PATCH 7/9] PCI/AER: Add RCEC AER handling

Jonathan Cameron
2020-07-27T17:16:07Z

On Mon, 27 Jul 2020 08:19:39 -0700
Sean V Kelley <sean.v.kelley@intel.com> wrote:

> On 27 Jul 2020, at 5:22, Jonathan Cameron wrote:
>
> > On Fri, 24 Jul 2020 10:22:21 -0700
> > Sean V Kelley <sean.v.kelley@intel.com> wrote:
> >
> >> The Root Complex Event Collectors(RCEC) appear as peers to Root Ports
> >> and also have the AER capability. So add RCEC support to the current
> >> AER
> >> service driver and attach the AER service driver to the RCEC device.
> >>
> >> Co-developed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
> >> Signed-off-by: Sean V Kelley <sean.v.kelley@intel.com>
> >> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
> >
> > A few questions and comments for this patch.
> >
> > See inline.
> >
> > Jonathan
> >
> >
> >> ---
> >> drivers/pci/pcie/aer.c | 34 +++++++++++++++++++++++++++-------
> >> 1 file changed, 27 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> >> index f1bf06be449e..7cc430c74c46 100644
> >> --- a/drivers/pci/pcie/aer.c
> >> +++ b/drivers/pci/pcie/aer.c
> >> @@ -303,7 +303,7 @@ int pci_aer_raw_clear_status(struct pci_dev *dev)
> >> return -EIO;
> >>
> >> port_type = pci_pcie_type(dev);
> >> - if (port_type == PCI_EXP_TYPE_ROOT_PORT) {
> >> + if (port_type == PCI_EXP_TYPE_ROOT_PORT || port_type ==
> >> PCI_EXP_TYPE_RC_EC) {
> >> pci_read_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, &status);
> >> pci_write_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, status);
> >> }
> >> @@ -389,6 +389,12 @@ void pci_aer_init(struct pci_dev *dev)
> >> pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_ERR, sizeof(u32) *
> >> n);
> >>
> >> pci_aer_clear_status(dev);
> >> +
> >> + if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC) {
> >> + if (!pci_find_ext_capability(dev, PCI_EXT_CAP_ID_RCEC))
> >> + return;
> >> + pci_info(dev, "AER: RCEC CAP FOUND and cap_has_rtctl = %d\n", n);
> >
> > It feels like failing to find an RC_EC extended cap in a RCEC deserved
> > a nice strong error message. Perhaps this isn't the right place to do
> > it
> > though. For that matter, why are we checking for it here?
>
> Sorry, I’ve left an in-development output in the code. Will replace
> with a check with more meaningful output elsewhere.
>
> >
> >> + }
> >> }
> >>
> >> void pci_aer_exit(struct pci_dev *dev)
> >> @@ -577,7 +583,8 @@ static umode_t aer_stats_attrs_are_visible(struct
> >> kobject *kobj,
> >> if ((a == &dev_attr_aer_rootport_total_err_cor.attr ||
> >> a == &dev_attr_aer_rootport_total_err_fatal.attr ||
> >> a == &dev_attr_aer_rootport_total_err_nonfatal.attr) &&
> >
> > It is a bit ugly to have these called rootport_total_err etc for the
> > rcec.
> > Perhaps we should just add additional attributes to reflect we are
> > looking at
> > an RCEC?
>
> I was trying to avoid any renaming to reduce churn as I did with my
> first patch for ACPI / CLX_OSC support.
> Will take a look.
>
> >
> >> - pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT)
> >> + ((pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT) &&
> >> + (pci_pcie_type(pdev) != PCI_EXP_TYPE_RC_EC)))
> >> return 0;
> >>
> >> return a->mode;
> >> @@ -894,7 +901,10 @@ static bool find_source_device(struct pci_dev
> >> *parent,
> >> if (result)
> >> return true;
> >>
> >> - pci_walk_bus(parent->subordinate, find_device_iter, e_info);
> >> + if (pci_pcie_type(parent) == PCI_EXP_TYPE_RC_EC)
> >> + pcie_walk_rcec(parent, find_device_iter, e_info);
> >> + else
> >> + pci_walk_bus(parent->subordinate, find_device_iter, e_info);
> >>
> >> if (!e_info->error_dev_num) {
> >> pci_info(parent, "can't find device of ID%04x\n", e_info->id);
> >> @@ -1030,6 +1040,7 @@ int aer_get_device_error_info(struct pci_dev
> >> *dev, struct aer_err_info *info)
> >> if (!(info->status & ~info->mask))
> >> return 0;
> >> } else if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
> >> + pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC ||
> >> pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM ||
> >> info->severity == AER_NONFATAL) {
> >>
> >> @@ -1182,6 +1193,8 @@ static int set_device_error_reporting(struct
> >> pci_dev *dev, void *data)
> >> int type = pci_pcie_type(dev);
> >>
> >> if ((type == PCI_EXP_TYPE_ROOT_PORT) ||
> >> + (type == PCI_EXP_TYPE_RC_EC) ||
> >> + (type == PCI_EXP_TYPE_RC_END) ||
> >
> > Why add RC_END here?
>
> I’m not clear on your question. Errors can come from RCEC or RCiEPs.
> We still need to enable reporting by the RCiEPs.

I was curious to see that we need it in this code path for an RCiEP but
not for a normal EP. From a quick glance it looks like that is often
done in the drivers for the EPs themselves rather than here.

>
> >
> >> (type == PCI_EXP_TYPE_UPSTREAM) ||
> >> (type == PCI_EXP_TYPE_DOWNSTREAM)) {
> >> if (enable)
> >> @@ -1206,9 +1219,11 @@ static void
> >> set_downstream_devices_error_reporting(struct pci_dev *dev,
> >> {
> >> set_device_error_reporting(dev, &enable);
> >>
> >> - if (!dev->subordinate)
> >> - return;
> >> - pci_walk_bus(dev->subordinate, set_device_error_reporting,
> >> &enable);
> >> + if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC)
> >> + pcie_walk_rcec(dev, set_device_error_reporting, &enable);
> >> + else if (dev->subordinate)
> >> + pci_walk_bus(dev->subordinate, set_device_error_reporting,
> >> &enable);
> >> +
> >> }
> >>
> >> /**
> >> @@ -1306,6 +1321,11 @@ static int aer_probe(struct pcie_device *dev)
> >> struct device *device = &dev->device;
> >> struct pci_dev *port = dev->port;
> >>
> >> + /* Limit to Root Ports or Root Complex Event Collectors */
> >> + if ((pci_pcie_type(port) != PCI_EXP_TYPE_RC_EC) &&
> >> + (pci_pcie_type(port) != PCI_EXP_TYPE_ROOT_PORT))
> >> + return -ENODEV;
> >> +
> >> rpc = devm_kzalloc(device, sizeof(struct aer_rpc), GFP_KERNEL);
> >> if (!rpc)
> >> return -ENOMEM;
> >> @@ -1362,7 +1382,7 @@ static pci_ers_result_t aer_root_reset(struct
> >> pci_dev *dev)
> >>
> >> static struct pcie_port_service_driver aerdriver = {
> >> .name = "aer",
> >> - .port_type = PCI_EXP_TYPE_ROOT_PORT,
> >> + .port_type = PCIE_ANY_PORT,
> >
> > Why this particular change? Seems that is a lot wider than simply
> > adding RCEC. Obviously we'll then drop out in the aer_probe but it
> > is still rather inelegant.
>
> In order to extend the service drivers to non-root-port devices (i.e.,
> RCEC), the simple path appeared to only require setting the type to
> ANY_PORT and catching the needed types arriving in the probe. Would you
> prefer extending to a type2? I’m not sure how one is more elegant
> than another but open to that approach. However, this seems to require
> less code perhaps and seems consistent with most ‘drop-out’
> conditional patterns in the kernel. The same applies to pme.

I'd miss understood this bit. It's fine as you have it here.

Jonathan

>
> Thanks,
>
> Sean
>
>
> >
> >> .service = PCIE_PORT_SERVICE_AER,
> >>
> >> .probe = aer_probe,