Re: [PATCH V4: 2/3] pci: Provide aer support when the error source id is bad

Andrew Patterson
2009-06-12T21:51:23Z

On Fri, 2009-06-12 at 11:08 +0800, Zhang, Yanmin wrote:
> ﻿﻿﻿When the bus id part of error source id is equal to 0 or nosourceid=1,
> kernel probes the AER status registers of all devices under the root port
> to find the initial error reporter.
>
> ﻿﻿﻿Signed-off-by: ﻿Zhang Yanmin <yanmin.zhang@linux.intel.com>
>
> ---
>
> --- linux-2.6_next_pciwalk/drivers/pci/pcie/aer/aerdrv_core.c 2009-06-12 05:31:53.000000000 +0800
> +++ linux-2.6_next_aernoid/drivers/pci/pcie/aer/aerdrv_core.c 2009-06-12 05:39:24.000000000 +0800
> @@ -26,7 +26,9 @@
> #include "aerdrv.h"
>
> static int forceload;
> +static int nosourceid;
> module_param(forceload, bool, 0);
> +module_param(nosourceid, bool, 0);
>
> int pci_enable_pcie_error_reporting(struct pci_dev *dev)
> {
> @@ -143,34 +145,82 @@ static void set_downstream_devices_error
> pci_walk_bus(dev->subordinate, set_device_error_reporting, &enable);
> }
>
> -static int find_device_iter(struct device *device, void *data)
> +static int compare_device_id(struct pci_dev *dev, struct aer_err_info *e_info)
> {
> - struct pci_dev *dev;
> - u16 id = *(unsigned long *)data;
> - u8 secondary, subordinate, d_bus = id >> 8;
> -
> - if (device->bus == &pci_bus_type) {
> - dev = to_pci_dev(device);
> - if (id == ((dev->bus->number << 8) | dev->devfn)) {
> - /*
> - * Device ID match
> - */
> - *(unsigned long*)data = (unsigned long)device;
> - return 1;
> - }
> -
> + if (e_info->id == ((dev->bus->number << 8) | dev->devfn)) {
> /*
> - * If device is P2P, check if it is an upstream?
> + * Device ID match
> */
> - if (dev->hdr_type & PCI_HEADER_TYPE_BRIDGE) {
> - pci_read_config_byte(dev, PCI_SECONDARY_BUS,
> - &secondary);
> - pci_read_config_byte(dev, PCI_SUBORDINATE_BUS,
> - &subordinate);
> - if (d_bus >= secondary && d_bus <= subordinate) {
> - *(unsigned long*)data = (unsigned long)device;
> - return 1;
> - }
> + e_info->dev = dev;
> + return 1;
> + }
> +
> + return 0;
> +}
> +
> +#define PCI_BUS(x) (((x) >> 8) & 0xff)
> +
> +static int find_device_iter(struct pci_dev *dev, void *data)
> +{
> + int pos;
> + u32 status;
> + u32 mask;
> + u16 reg16;
> + struct aer_err_info *e_info = (struct aer_err_info *)data;
> +
> + /*
> + * When bus id is equal to 0, it might be a bad id
> + * reported by root port.
> + */
> + if (!nosourceid && (PCI_BUS(e_info->id) != 0))
> + return compare_device_id(dev, e_info);
> +
> + /*
> + * Next is to check when bus id is equal to 0 or
> + * nosourceid==y. Some ports might lose the bus
> + * id of error source id. We check AER status
> + * registers to find the initial reporter.
> + */
> + if (atomic_read(&dev->enable_cnt) == 0)
> + return 0;
> + pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
> + if (!pos)
> + return 0;
> + /* Check if AER is enabled */
> + pci_read_config_word(dev, pos+PCI_EXP_DEVCTL, &reg16);
> + if (!(reg16 & (
> + PCI_EXP_DEVCTL_CERE |
> + PCI_EXP_DEVCTL_NFERE |
> + PCI_EXP_DEVCTL_FERE |
> + PCI_EXP_DEVCTL_URRE)))
> + return 0;
> + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
> + if (!pos)
> + return 0;
> +
> + status = 0;
> + mask = 0;
> + if (e_info->severity == AER_CORRECTABLE) {
> + pci_read_config_dword(dev,
> + pos + PCI_ERR_COR_STATUS,
> + &status);
> + pci_read_config_dword(dev,
> + pos + PCI_ERR_COR_MASK,
> + &mask);
> + if (status & ERR_CORRECTABLE_ERROR_MASK & ~mask) {
> + e_info->dev = dev;
> + return 1;
> + }
> + } else {
> + pci_read_config_dword(dev,
> + pos + PCI_ERR_UNCOR_STATUS,
> + &status);
> + pci_read_config_dword(dev,
> + pos + PCI_ERR_UNCOR_MASK,
> + &mask);
> + if (status & ERR_UNCORRECTABLE_ERROR_MASK & ~mask) {
> + e_info->dev = dev;
> + return 1;
> }
> }
>
> @@ -180,33 +230,23 @@ static int find_device_iter(struct devic
> /**
> * find_source_device - search through device hierarchy for source device
> * @parent: pointer to Root Port pci_dev data structure
> - * @id: device ID of agent who sends an error message to this Root Port
> + * @err_info: including detailed error information such like id
> *
> * Invoked when error is detected at the Root Port.
> */
> -static struct device* find_source_device(struct pci_dev *parent, u16 id)
> +static void find_source_device(struct pci_dev *parent,
> + struct aer_err_info *e_info)
> {
> struct pci_dev *dev = parent;
> - struct device *device;
> - unsigned long device_addr;
> - int status;
> + int result;
>
> /* Is Root Port an agent that sends error message? */
> - if (id == ((dev->bus->number << 8) | dev->devfn))
> - return &dev->dev;
> -
> - do {
> - device_addr = id;
> - if ((status = device_for_each_child(&dev->dev,
> - &device_addr, find_device_iter))) {
> - device = (struct device*)device_addr;
> - dev = to_pci_dev(device);
> - if (id == ((dev->bus->number << 8) | dev->devfn))
> - return device;
> - }
> - }while (status);
> + result = find_device_iter(dev, e_info);
> + if (result)
> + return;
>
> - return NULL;
> + pci_walk_bus(parent->subordinate, find_device_iter, e_info);

Minor nit. This return is redundant.

> + return;
> }
>

Minor. The e_info goes to pointer changes probably belong in a separate
patch.

> static int report_error_detected(struct pci_dev *dev, void *data)
> @@ -501,12 +541,12 @@ static pci_ers_result_t do_recovery(stru
> */
> static void handle_error_source(struct pcie_device * aerdev,
> struct pci_dev *dev,
> - struct aer_err_info info)
> + struct aer_err_info *info)
> {
> pci_ers_result_t status = 0;
> int pos;
>
> - if (info.severity == AER_CORRECTABLE) {
> + if (info->severity == AER_CORRECTABLE) {
> /*
> * Correctable error does not need software intevention.
> * No need to go through error recovery process.
> @@ -514,9 +554,9 @@ static void handle_error_source(struct p
> pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
> if (pos)
> pci_write_config_dword(dev, pos + PCI_ERR_COR_STATUS,
> - info.status);
> + info->status);
> } else {
> - status = do_recovery(aerdev, dev, info.severity);
> + status = do_recovery(aerdev, dev, info->severity);
> if (status == PCI_ERS_RESULT_RECOVERED) {
> dev_printk(KERN_DEBUG, &dev->dev, "AER driver "
> "successfully recovered\n");
> @@ -673,10 +713,13 @@ static int get_device_error_info(struct
> static void aer_isr_one_error(struct pcie_device *p_device,
> struct aer_err_source *e_src)
> {
> - struct device *s_device;
> - struct aer_err_info e_info = {0, 0, 0,};
> + struct aer_err_info *e_info;
> int i;
> - u16 id;
> +
> + /* struct aer_err_info might be big, so we allocate it with slab */
> + e_info = kmalloc(sizeof(struct aer_err_info), GFP_KERNEL);
> + if (e_info == NULL)
> + return;
>
Should we get some sort of warning here? We might be concealing PCIe
errors when out of memory.

> /*
> * There is a possibility that both correctable error and
> @@ -688,31 +731,37 @@ static void aer_isr_one_error(struct pci
> if (!(e_src->status & i))
> continue;
>
> + memset(e_info, 0, sizeof(struct aer_err_info));
> +
> /* Init comprehensive error information */
> if (i & PCI_ERR_ROOT_COR_RCV) {
> - id = ERR_COR_ID(e_src->id);
> - e_info.severity = AER_CORRECTABLE;
> + e_info->id = ERR_COR_ID(e_src->id);
> + e_info->severity = AER_CORRECTABLE;
> } else {
> - id = ERR_UNCOR_ID(e_src->id);
> - e_info.severity = ((e_src->status >> 6) & 1);
> + e_info->id = ERR_UNCOR_ID(e_src->id);
> + e_info->severity = ((e_src->status >> 6) & 1);
> }
> if (e_src->status &
> (PCI_ERR_ROOT_MULTI_COR_RCV |
> PCI_ERR_ROOT_MULTI_UNCOR_RCV))
> - e_info.flags |= AER_MULTI_ERROR_VALID_FLAG;
> - if (!(s_device = find_source_device(p_device->port, id))) {
> + e_info->flags |= AER_MULTI_ERROR_VALID_FLAG;
> +
> + find_source_device(p_device->port, e_info);
> + if (e_info->dev == NULL) {
> printk(KERN_DEBUG "%s->can't find device of ID%04x\n",
> - __func__, id);
> + __func__, e_info->id);
> continue;
> }
> - if (get_device_error_info(to_pci_dev(s_device), &e_info) ==
> + if (get_device_error_info(e_info->dev, e_info) ==
> AER_SUCCESS) {
> - aer_print_error(to_pci_dev(s_device), &e_info);
> + aer_print_error(e_info->dev, e_info);
> handle_error_source(p_device,
> - to_pci_dev(s_device),
> + e_info->dev,
> e_info);
> }
> }
> +
> + kfree(e_info);
> }
>
> /**
> --- linux-2.6_next_pciwalk/drivers/pci/pcie/aer/aerdrv.h 2009-06-12 05:27:46.000000000 +0800
> +++ linux-2.6_next_aernoid/drivers/pci/pcie/aer/aerdrv.h 2009-06-12 05:39:24.000000000 +0800
> @@ -58,6 +58,8 @@ struct header_log_regs {
> };
>
> struct aer_err_info {
> + struct pci_dev *dev;
> + u16 id;
> int severity; /* 0:NONFATAL | 1:FATAL | 2:COR */
> int flags;
> unsigned int status; /* COR/UNCOR Error Status */
> --- linux-2.6_next_pciwalk/Documentation/PCI/pcieaer-howto.txt 2009-06-12 05:27:40.000000000 +0800
> +++ linux-2.6_next_aernoid/Documentation/PCI/pcieaer-howto.txt 2009-06-12 05:39:24.000000000 +0800
> @@ -60,6 +60,8 @@ forceload, a parameter of type bool, cou
> be initiated although firmwares have no _OSC support. To enable the
> walkaround, pls. add aerdriver.forceload=y to kernel boot parameter line
> when booting kernel. Note that forceload=n by default.

We need a new paragraph here.
> +nosourceid, another parameter of type bool, is used when hardware (mostly
> +chipset) has errata that root ports couldn't get error reporting source id.
>

Perhaps ".. can be used when broken hardware (mostly chipsets) has root
ports that cannot obtain the reporting source ID."

> 2.3 AER error output
> When a PCI-E AER error is captured, an error message will be outputed to
>
>
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--
Andrew Patterson
Hewlett-Packard