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

Jonathan Cameron
2020-07-27T12:24:19Z

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?

> + }
> }
>
> 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?

> - 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?

> (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.

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