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powerpc/eeh: Add debugfs interface to run an EEH check 

Detecting an frozen EEH PE usually occurs when an MMIO load returns a 0xFFs
response. When performing EEH testing using the EEH error injection feature
available on some platforms there is no simple way to kick-off the kernel's
recovery process since any accesses from userspace (usually /dev/mem) will
bypass the MMIO helpers in the kernel which check if a 0xFF response is due
to an EEH freeze or not.

If a device contains a 0xFF byte in it's config space it's possible to
trigger the recovery process via config space read from userspace, but this
is not a reliable method. If a driver is bound to the device an in use it
will frequently trigger the MMIO check, but this is also inconsistent.

To solve these problems this patch adds a debugfs file called
"eeh_dev_check" which accepts a <domain>:<bus>:<dev>.<fn> string and runs
eeh_dev_check_failure() on it. This is the same check that's done when the
kernel gets a 0xFF result from an config or MMIO read with the added
benifit that it can be reliably triggered from userspace.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190903101605.2890-13-oohall@gmail.com
This commit is contained in:
Oliver O'Halloran 2019-09-03 20:16:03 +10:00 committed by Michael Ellerman
parent aeff27c121
commit 22cda7c168
1 changed files with 61 additions and 0 deletions
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61
arch/powerpc/kernel/eeh.c
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@ -1871,6 +1871,64 @@ static const struct file_operations eeh_force_recover_fops = {
.llseek = no_llseek,
.write = eeh_force_recover_write,
};
static ssize_t eeh_debugfs_dev_usage(struct file *filp,
char __user *user_buf,
size_t count, loff_t *ppos)
{
static const char usage[] = "input format: <domain>:<bus>:<dev>.<fn>\n";
return simple_read_from_buffer(user_buf, count, ppos,
usage, sizeof(usage) - 1);
}
static ssize_t eeh_dev_check_write(struct file *filp,
const char __user *user_buf,
size_t count, loff_t *ppos)
{
uint32_t domain, bus, dev, fn;
struct pci_dev *pdev;
struct eeh_dev *edev;
char buf[20];
int ret;
ret = simple_write_to_buffer(buf, sizeof(buf), ppos, user_buf, count);
if (!ret)
return -EFAULT;
ret = sscanf(buf, "%x:%x:%x.%x", &domain, &bus, &dev, &fn);
if (ret != 4) {
pr_err("%s: expected 4 args, got %d\n", __func__, ret);
return -EINVAL;
}
pdev = pci_get_domain_bus_and_slot(domain, bus, (dev << 3) | fn);
if (!pdev)
return -ENODEV;
edev = pci_dev_to_eeh_dev(pdev);
if (!edev) {
pci_err(pdev, "No eeh_dev for this device!\n");
pci_dev_put(pdev);
return -ENODEV;
}
ret = eeh_dev_check_failure(edev);
pci_info(pdev, "eeh_dev_check_failure(%04x:%02x:%02x.%01x) = %d\n",
domain, bus, dev, fn, ret);
pci_dev_put(pdev);
return count;
}
static const struct file_operations eeh_dev_check_fops = {
.open = simple_open,
.llseek = no_llseek,
.write = eeh_dev_check_write,
.read = eeh_debugfs_dev_usage,
};
#endif
static int __init eeh_init_proc(void)
@ -1886,6 +1944,9 @@ static int __init eeh_init_proc(void)
debugfs_create_bool("eeh_disable_recovery", 0600,
powerpc_debugfs_root,
&eeh_debugfs_no_recover);
debugfs_create_file_unsafe("eeh_dev_check", 0600,
powerpc_debugfs_root, NULL,
&eeh_dev_check_fops);
debugfs_create_file_unsafe("eeh_force_recover", 0600,
powerpc_debugfs_root, NULL,
&eeh_force_recover_fops);